CHAPTER 2
FORECAST AND WARNING SERVICES
2.1 INTRODUCTION
The Northeast Floods of January 1996 created challenges for all National Weather
Service (NWS) offices involved in issuing timely and accurate forecasts, watches,
advisories, warnings, statements, and other public products. Hundreds of forecasts
were issued under very complicated and unprecedented conditions. In spite of the rapid
onset and complexity of this event, NWS personnel provided excellent service to the
public and specialized users. See Figure 2.1 for a map showing all counties under
Flash Flood/Flood Warnings.
Public forecasts and warning products issued by NWS offices in areas impacted by this
major flood event accurately highlighted the weather as it developed across their areas
of responsibility. Products were well written, timely, and contained good call-to-action
statements. Flood Potential Statements issued earlier in the week provided the public,
media, and public safety officials with information concerning flood potential.
Flood watches were posted on Wednesday afternoon, January 17, by the Next
Generation Weather Radar (NEXRAD) Weather Service Forecast Office (NWSFO) in
Pittsburgh, Pennsylvania, for eastern Ohio and west central Pennsylvania, and were
extended for all of each central Ohio, western Pennsylvania, and northern West
Virginia on Thursday, January 18. Also on January 18, watches were posted by
NWSFO Charleston, West Virginia, for a significant portion of West Virginia and the
New River Valley of southwest Virginia. Additional watches were issued on Thursday
afternoon by the NWSFOs in Albany and Buffalo, New York, for central and eastern
New York, and the NWSFO Baltimore, Maryland/Washington, DC, for portions of
Virginia, West Virginia, and Maryland. NWSFO Philadelphia, Pennsylvania, issued a
flood watch Thursday afternoon for extreme southeast Pennsylvania and portions of
New Jersey, Maryland, and Delaware, and for the remainder of eastern Pennsylvania
and New Jersey early on Friday morning.
All offices in the flood-impacted area maintain a Hydrologic Service Area (HSA) under
the modernization of the NWS. The Middle Atlantic River Forecast Center (MARFC)
and Ohio River Forecast Center (OHRFC) are responsible for providing flash flood,
headwaters, and river forecast guidance to offices with HSA responsibility. The
NWSFOs and NEXRAD Weather Service Offices (NWSO), in turn, develop a suite of
public hydrologic products based on the guidance received from the RFCs. They are
also responsible for releasing those forecast and warning products to the public and
specific users through several communication mediums. One significant aspect of this
event was that this was the first major widespread flood event following the HSA
transfer in Stage I of the NWS's Modernization and Associated Restructuring (MAR).
HSA offices maintain a network of observational sites and work with other Federal,
state, and local governments in maintaining special gage networks such as Automated
Local Evaluation in Real Time (ALERT) and Integrated Flood Observing and Warning
System (IFLOWS). They also maintain information and history on each river gage site
through consistent review and updates to the standard NWS form E-19. E-19s are
generally updated every several years and/or after significant flooding.
All offices had recently or were in the process of updating their E-19s. For statement
writing purposes, E-19s contain a wealth of information concerning flood impact at
various river levels. This information provides the public with a more visual picture as
to which areas will flood when river levels reach certain stages. This information was
readily available and used in the many statements, forecasts, and warnings issued
during the event.
A responsibility of the HSA office is to provide the RFCs with daily Quantitative
Precipitation Forecasts (QPF). This information is a mean areal outline of the average
amount of precipitation that will fall on an HSA basin over a 24-hour period in 6-hour
increments. In the Eastern Region, only NWSFOs issued daily QPF products in
January 1996; however, during 1997, all Eastern Region spin-up NWSOs began issuing
QPF products.
Areal average 24-hour QPF forecasts issued on Thursday, January 18, by the NWSFOs
in Pittsburgh, Pennsylvania, and Charleston, West Virginia, ranged from 0.25-0.5 and
0.5-1 inch, respectively. QPF forecasts released early Friday morning, January 19, by
NWSFOs in Pittsburgh, Pennsylvania; Philadelphia, Pennsylvania; Albany, New York;
and Baltimore, Maryland/Washington, DC, contained amounts ranging from 0.25-0.75
inch.
All QPF products were later updated and increased to amounts over 1.5 inches to
reflect the heavy precipitation which fell late Thursday, January 18, into early Friday,
January 19, across the Ohio Valley and the northeast United States. Doppler Weather
Surveillance Radar (WSR-88D) precipitation estimates and National Center for
Environmental Prediction (NCEP) numerical model QPFs underplayed the amount of
rainfall revealed by gage observations on Friday morning. Additionally, the hydrologic
model under forecasted the rate of snowmelt compounding the flood forecast problem.
Since this event impacted several states and resulted in the issuance of numerous
products and the rendering of many services by all NWS offices involved, the rest of
this section will provide an office-by-office overview and summary of major forecast
and warning actions taken. Table 2.1 summarizes these products by office.
Table 2.1 Nonroutine products issued before and during the event by the NWSFO and
NWSO offices through Sunday, January 21, 1996
LEGEND: ESF - Flood Potential Statement SPS - Special Weather Statement
FFA - Flash Flood Watch FFW - Flash Flood Warning
FFS - Flash Flood Statement FLW - Flood Warning for Rivers
FLS - Flood Statement RVS - River Statement
RVI - Ice Jam Statement SVR - Severe Thunderstorm Warning
NPW - Non-Precipitation Event
2.2 INDIVIDUAL OFFICE PERFORMANCE
2.2.1 NWSFO BALTIMORE, MARYLAND/WASHINGTON, DC
Shortly after the Blizzard of 1996, Baltimore/Washington forecasters realized that flood
and ice jam problems could result from strong warm air advection forecasted across
Virginia and Maryland on January 17-18. Based on numerical model runs from NCEP,
forecasters were looking for a significant warming trend to begin Thursday, January
19. In response to this forecast and hydrologic contingency model runs accomplished
by the MARFC, a Flood Potential Statement was issued Monday, January 15, at 2:18
p.m. EST which discussed the potential for urban flooding, possible flash flooding, and
the likelihood of river flooding due to ice jams. Also on Monday, a flood potential
briefing was provided to West Virginia Emergency Services showing that the eastern
panhandle of West Virginia would be impacted mainly by urban and small stream
flooding and river flooding due to ice jams.
A second Flood Potential Statement was issued at noon on Wednesday, January 17. In
this statement, it was again stressed that flooding would occur at the end of the week
and over the weekend. The statement noted that the area would receive over 1 inch of
rain from an approaching system forecasted to cross Virginia, West Virginia, and
Maryland on Friday, January 19. The statement also mentioned that this precipitation
amount, along with some anticipated snowmelt, would bring the Potomac, Shenandoah,
and Rappahannock river basins to near flood stage. On Thursday, January 18, a River
Statement was issued that detailed ice jam problems on the Potomac, Shenandoah, and
upper Rappahannock rivers and reinforced the fact that rainfall during the next 24 hours
would cause those rivers to rise and many creeks to reach bank full.
As the event unfolded overnight Thursday, January 18, into Friday, January 19, it was
discovered the meteorological models had underplayed the magnitude of this event.
Earlier forecasted precipitation amounts were for 1-1.5 inches of rainfall. However,
more than 3- to 4-inch amounts fell on some basins with 2 inches being the norm. A
flood watch for flash flooding of small creeks and streams was posted on Thursday.
Also, because the amount of snowmelt was not anticipated Thursday earlier river
forecasts issued late Thursday and early Friday did not reflect this additional runoff.
This resulted in under forecasted river stages. Once the snowmelt and increased
precipitation amounts were ingested into the models late Friday morning, stage
forecasts became significantly better throughout the rest of the event.
A River Flood Statement was issued at 2:32 a.m. EST on Friday, January 19. Rivers
were still several feet below flood stage but were rising slowly. This statement noted
that both the upper and lower Potomac and Shenandoah rivers would begin to rise
sharply, and warnings would be needed later in the morning. Call-to-action statements
were included to inform the public to prepare for evacuation if a warning was issued
and to not cross water covered roads. Within an hour, a River Flood Warning was
issued for the south branch of the Potomac River at Franklin and Petersburg, West
Virginia. Crest information was provided along with appropriate call-to-action
statements. It was noted that rivers could rise even higher than forecasted if more rain
and snowmelt occurred.
Another River Flood Warning was issued at 4:15 a.m. EST Friday, January 19, for the
north branch of the Potomac River at Kitzmiller, Maryland. By early Friday
afternoon, most of Baltimore/Washington's river forecast points in the upper basins of
the Potomac, Shenandoah, and Rappahannock were under a Flood Warning. All
remaining points, especially across lower basin areas, were placed under Flood
Warnings Friday night and Saturday morning.
New MARFC river forecast guidance was received between 10:42 and 11:43 a.m. EST
on Friday, January 19. Initial river forecasts were too low, so upward adjustments
were coordinated. Based on the information received after the initial MARFC model
forecast runs, forecasted river crest levels were increased by 1-7 feet across the upper
reaches of all basins. MARFC guidance improved considerably after the snowmelt and
additional precipitation were ingested into the forecast model. Later, guidance was
only adjusted 1-3 feet at some locations.
Other routine forecast operations continued while issuing Severe Thunderstorm
Warnings, a High Wind Warning for much of the County Warning Areas (CWA), and
Flash Flood Warnings throughout the event. The issuance of Flash Flood Warnings
began shortly after midnight Friday and continued until around noon in response to
calls received from public safety officials reporting road closures and washouts, flood
damage, mud slides, and evacuations and rescues from already flooded areas.
In Baltimore, Maryland/Washington, DC, all but two gages exceeded their flood stage
with some approaching the record flood events of 1985, 1972, 1942, and 1936. Many
follow-up statements and warning updates were issued to keep the public, media, and
emergency managers informed on both the current and forecasted conditions.
As a result of the river and flash flooding, evacuations were conducted in Kitzmiller,
Maryland; Franklin and Petersburg, West Virginia; and Shenandoah County, Virginia.
Virginia and Maryland declared flood emergencies for several counties. By late
Saturday and Sunday, rivers had crested and began to recede to the point that some
warnings were canceled. By Tuesday morning, all river stage points were below flood
stage.
2.2.2 NWSO STATE COLLEGE, PENNSYLVANIA
The flood event of January 19-21, 1996, produced extremely rapid rises of rivers and
streams across the entire CWA. This was the worst flooding for this region since
Tropical Storm Agnes in June of 1972. Flash and river flooding occurred in all 33
counties of State College's CWA. Flood stages were equaled or exceeded at 36 river
forecast points. A flood of record was established at Williamsburg, Pennsylvania, on
the Frankstown branch of the Juniata River and at Loyalsockville on the Loyalsock
Creek. Many other crests ranked in the top five of the highest peaks on record.
Across central Pennsylvania, the primary cause of many of the rises was attributable to
ice movement and jams. The Susquehanna River at Harrisburg. Pennsylvania, rose
almost 13 feet in 2 hours during the evening of Friday, January 19. This rise exceeded
all previous record rises for this gage location. Many rivers and streams rose from
below normal flow to flood stage and higher within a few hours. The hardest hit area
was Lycoming creek north of Williamsport, Pennsylvania. Flooding exceeded records
established by Tropical Storm Agnes.
On Thursday morning, January 18, 1996, NWSO State College provided a detailed
statement concerning warm temperatures, snowmelt, rain, and the potential for
significant rises on rivers and streams in central Pennsylvania for late Thursday night
and Friday. Ponding of water in poor drainage areas and flooding of roadways due to
clogged storm drains were predicted. Flood Potential Statements were issued on
January 16-17. The possibility of ice breakup and ice jams was mentioned, and
localized flooding would develop rapidly if ice jams were to form.
A Flood Watch posted for all of western Pennsylvania by NWSFO Pittsburgh on
Thursday afternoon, January 18, for Thursday night and Friday, provided a lengthy
alert for the citizens of that area. Flood Watches were posted across the east portion of
Pennsylvania early Friday morning, January 19, at the request of NWSO State College
to NWSFO Philadelphia, Pennsylvania. Office staffing was increased early Friday
with the arrival of the Warning Coordination Meteorologist (WCM) and Service
Hydrologist (SH) at 5 a.m. EST.
Initial Flood Warnings from NWSO State College were issued Friday, January 19, at
5:30 a.m. EST, coincident with reports of heavy rain and flooding. Also, WSR-88D
radar rainfall estimates exceeding 0.5 inches of rain per hour extended from western
Elk County south into western Cambria and Somerset counties. The first warnings
were issued for Somerset, Cambria, Clearfield, Elk, McKean, and Warren Counties.
By 6:23 a.m. EST on Friday, January 19, Flash Flood Warnings were extended east
across Bedford, Blair, Cameron, Centre, Clinton, Fulton, Huntingdon, and Potter
counties. At 6:47 a.m. EST, warnings were issued further east ahead of the heavy
rain. By 7:01 a.m. EST, State College's final group of eastern counties were placed
under a Flood Warning. Many warnings were issued with a good lead time before
significant flooding began late Friday morning and before any deaths occurred Friday
evening. River Flood Warnings were issued at 6:55 a.m. EST for the Allegheny
basin, 9 a.m. EST for the Juniata basin, 10 a.m. EST for the Susquehanna basin, and
11:30 a.m. EST for the main stem of the Susquehanna River.
Throughout Friday morning, January 19, a high wind event also prevailed across much
of Pennsylvania causing structural damage to buildings in Franklin County. Some
minor damage also occurred in other areas. During the mid-morning hours, as heavy
rain continued across the region, NWSO State College issued strongly worded update
warnings and flood statements using the terms "this is a severe flood event," "this is a
major flood event," and "major flooding will continue." A late morning statement
predicted that major flooding would continue through the afternoon even after the rain
ended.
All warnings and statements cautioned against driving across flooded roadways or
trying to cross a flowing stream on foot. A late afternoon statement for the Clarion
River in Ridgeway, Pennsylvania, noted that the river stage forecasted to crest at 21
feet would exceed the old stage record of 19.5 set by Tropical Storm Agnes.
Statements also relayed recommendations by the Lycoming County emergency
management for evacuations of those areas that had been flooded out by Tropical Storm
Agnes.
By noon Friday, January 19, all HSA major river basins were under River Flood
Warnings. As the magnitude of the rainfall and snowmelt became clearer, forecast
point warnings became more numerous and accurate with 36 river forecast point
warnings in effect by Friday afternoon.
2.2.3 NWSO BINGHAMTON, NEW YORK
NWSO Binghamton began issuing Flood Potential Outlooks for the event at 3 p.m.
EST on Tuesday, January 16, singling out Friday, January 19, as the day for potential
flooding. Additional Flood Potential Statements were issued at 11 a.m. EST on both
Wednesday and Thursday.
Briefings to local officials and media concerning the flood threat began on Wednesday,
January 17. On Thursday, two local TV stations carried stories on the flood threat for
Friday, January 19. On the morning of January 19, the Binghamton morning
newspaper ran a front page story with the headline "January Thaw Brings Threat of
Floods" and subtitled "Huge S. Tier Snow Pack Hides Danger." The SH at NWSO
Binghamton was quoted from an interview on January 18: "We have between 1-2 feet
of snow on the ground. If that were to melt quickly, we would have problems." Also
in the article, Jean Shaw, Director of Emergency Services for the Red Cross Southern
Tier Chapter, said she was getting volunteers ready to cope with flooding should it
occur. "We know we're in a high-risk area," she said in the article.
As part of its forecaster training efforts, NWSO Binghamton routinely issues "shadow
zone forecasts" (ZPF) for 11 counties and forecast discussions (AFD) four times daily.
These forecasts are usually adopted without modification by NWSFOs in Albany and
Buffalo. The AFD issued at 1:25 a.m. on Thursday, January 18, asked the day shift to
consider the issuance of flood watches for Friday. Late Thursday morning, NWSO
Binghamton management made contingency plans for augmented operational staffing
for January 19-20.
During the early after on Thursday, January 18, NWSO Binghamton initiated
coordination to issue a flood watch for all of central New York and northeast
Pennsylvania. Concurring with NWSO Binghamton's recommendation, NWSFOs at
Albany and Buffalo issued flood watches for all of central New York at 4 p.m. EST
highlighting snowmelt runoff and significant rainfall that would cause rises on streams
and the potential for ice jam flooding. Disagreeing with NWSO Binghamton's
recommendation, NWSFO Philadelphia, Pennsylvania, chose to hold off issuing a
flood watch.
During the early evening on Thursday, January 18, the volunteer SKYWARN spotter
coordinator for the Binghamton warning area put out a message for all spotters to "keep
their eyes open" Thursday night and Friday due to the high wind and flood risks.
Between 3-5 a.m. EST on Friday, January 19, NWSO Binghamton spoke with 18 of 24
counties asking for any flood reports and requesting that they call on their 1-800
number with any reports of flooding. As of 5 a.m. EST, no flooding was reported
except in Steuben (minor flooding) and Bradford (lowland flooding by one creek)
counties. Based on these reports, the meteorologists on duty determined that rapid
snowmelt and light rainfall had caused streams to rise to, or just over, bankfull in these
two counties.
The bankfull conditions, along with the short-term forecast that several hours of heavy
rain would occur in these areas between 7-11 a.m. EST, resulted in the issuance of
NWSO Binghamton's first Flood Warning at 5:15 a.m. EST, on Friday, January 19,
for Steuben County, New York, and Bradford County, Pennsylvania. This initial
warning was notable for including a specific QPF forecast for 1 inch of rain that would
generate additional flooding.
Between 5:15-8 a.m. EST, NWSO Binghamton received reports of numerous flooding
problems in Steuben county, most associated with ice jams. Other counties began
reporting some poor drainage flooding, lowland flooding, and in a couple of counties,
isolated creeks started coming out of their banks. Given that many streams were
bankfull, rapid snowmelt runoff was ongoing, and a prediction that heavy rain would
spread east across the remainder of the CWA between 10 a.m. to 4 p.m. EST, NWSO
Binghamton took the aggressive step of issuing warnings between 8-8:30 a.m. EST to
all remaining CWA counties except Sullivan, New York, where a warning was issued
at 12:04 p.m. EST. As with their first warnings, all of these warnings contained a
specific QPF forecast for 1 inch of additional rain.
NWSO Binghamton's actions in issuing Flood Warnings for 21 counties in less than 30
minutes between 8-8:30 a.m. EST, indicates that they were able to effectively assess
current conditions and integrate their own short-term QPF forecasts into their decision-
making process. As a result, they quickly recognized the widespread nature of the
flood threat. Issuance of these warnings, up to 4 hours before heavy rainfall even
began, resulted in significant lead times in most areas.
Flood Statements and re-issued warnings throughout the morning and early afternoon
hours provided additional QPF forecasts. Details on reported flooding and enhanced
wording provided descriptions of the heavy rains and its impact on flooding. As the
event continued to unfold, NWSO Binghamton increased the severity of their warnings,
alerting the users about the magnitude and impact of the flooding. The office also
included discussions of disaster and emergency declarations.
At 7:04 p.m. EST, Friday, January 19, a Flood Statement was issued concerning
recommended evacuations along the Little Mehoopany Creek in Wyoming County,
Pennsylvania, due to an overtopped dam that was in danger of failing.
As illustrated above, on Friday, January 19, NWSO Binghamton issued warnings and
statements throughout the day including specific QPF forecasts and detail that
substantially enhanced their information content and effectiveness.
A River Flood Warning was issued Friday, January 19, at 8:23 a.m. EST for Conklin,
New York, on the Susquehanna River, and Sherburne, New York, on the Chenango
River, for flooding due to ice jams. A Flood Warning was issued at 9:33 a.m. EST for
the Tioughnioga River to exceed the 8-foot flood stage around noon at Cortland, New
York, due to snowmelt and approaching heavy rainfall.
Additional Flood Warnings were issued Friday, January 19, for the Chemung and
Upper Susquehanna Basins between 10-11:30 a.m. EST, and for the Upper Delaware
Basin at 1 p.m. EST. With improved MARFC forecast guidance, the crest forecasts
for many points in those basins were increased between 11:30 a.m. and 4:15 p.m.
EST, and increased again between 9:25 p.m. and 10:30 p.m. EST. Most points
crested late Friday night and Saturday.
Severe Thunderstorm Warnings were issued Friday, January 19, between 12:33-1:15
p.m. EST, for Pike and Wayne counties in northeast Pennsylvania, when a bow echo
formed on a line of storms accompanying the cold front. When this line passed across
northeast Pennsylvania, Wilkes-Barre/Scranton Airport reported a wind gust to 60 mph
without thunder. It was reported that because of high winds, trees and wires were
down during Friday morning in the New York counties of Broome, Delaware, and
Otsego. Many of the above warning products issued were summarized in hourly short-
term forecasts and special and hydrologic statement products.
Main-stem rivers had risen rapidly Friday afternoon, January 19, so many public safety
officials anticipated citizen evacuations. There were numerous phone calls at the
Binghamton office from county and city emergency management officials who wanted
immediate flood forecast updates. During early Friday evening, there was considerable
pressure placed on the Binghamton office for critical stage forecasts. Through all of
Friday and Saturday, the forecast staff was supported by the Meteorologist-in-Charge
(MIC), Science and Operations Office (SOO), WCM, and SH, The SH handled most
of the coordination calls and assisted in issuing products.
NWSO Binghamton had requested several key flood forecasts for the north branch of
the Susquehanna River from the MARFC around 6 p.m. EST Friday, January 19, but
they did not receive them until after 9:15 p.m. EST. At 9:19 p.m. EST, MARFC
released the Chemung basin forecasts, and at 9:45 p.m. EST the lower Susquehanna
basin forecasts were available. However, critical Susquehanna river stage forecasts
from Wilkes-Barre north to the New York border were not received until around 10
p.m. EST. Although the Wilkes-Barre stage forecast was received later than
anticipated, the forecast value at Wilkes-Barre was nearly perfect, within one-half foot
of where the river finally crested (34.4 feet) Saturday afternoon. The top of the
protection levee around Wilkes-Barre is 37 feet, so the 35-foot forecast was extremely
important in the decision of local officials to initiate a major precautionary evacuation
of 110,000 residents in and around the city of Wilkes-Barre, Pennsylvania. Because of
the accurate forecast provided 16 hours prior to the crest, an orderly evacuation could
be conducted over an 8-hour period. Subsequent to the event, local citizens and the
media expressed overwhelming support of this decision.
Throughout the event, numerous flood and severe weather products were issued by the
Binghamton staff. All rivers in the HSA were under a warning from late Friday
morning, January 19, until Sunday and Monday. All counties were placed under Flash
Flood Warnings and Several Severe Thunderstorm Warnings were posted for counties
in New York and Pennsylvania. All gage points in Binghamton's HSA exceeded flood
stage, with some levels approaching or exceeding record values.
2.2.4 NWSFO PHILADELPHIA, PENNSYLVANIA
Two days prior to flooding in their CWA, NWSFO Philadelphia issued a Special
Weather Statement at 12 p.m. EST Wednesday, January 17, describing that minor
flooding was possible on Friday, January 19. However, the statement indicated that
stream and river flooding was unlikely because of the forecast at that time.
The next Special Weather Statement was issued on Thursday, January 18, at 4 a.m.
EST, and reiterated that nuisance and drainage flooding could occur on Friday, January
19. Also on Thursday, forecasters at NWSFO Philadelphia coordinated with NWSO
Binghamton, New York, concerning the possibility of flooding on upper Delaware
basin in southern New York and northeast Pennsylvania. A Flood Watch was posted
Thursday afternoon at 3:50 p.m. EST for sections of New Jersey, Delaware, and
extreme southeast Pennsylvania. This statement was the first to indicate that river and
stream flooding could occur as a result of shifting ice and ice jams. It also mentioned
that roads may become impassable by Friday evening, January 19, due to the flooding.
Later Thursday, a follow-up Flood Watch Statement was issued around 10 p.m. EST
for the same areas.
At 5:15 a.m. EST Friday, January 19, NWSFO Philadelphia issued a flood watch that
covered the rest of their forecast area to include all of eastern Pennsylvania. Stream,
creek, and urban flooding was again the main focus of this statement and it also
included call-to-action statements. Because of the possibility of a high tide at noon
Friday, a River Flood Statement was issued to describe the possibility of flooding on
tidal sections of the Delaware river extending up to Philadelphia.
At 8:04 a.m. EST, the first warning was issued for the Christina River in New Castle
County, Delaware. An automatic gage report indicated 8.1 feet. Flood stage for this
point is 9 feet. By 10 a.m. EST, it was evident to the NWSFO staff that the snowmelt
was more pronounced than expected, so additional flood warnings for small stream and
urban areas were posted for many of the counties in NWSFO Philadelphia's CWA.
Although river flooding was not occurring yet, some flash flooding was occurring in
central Pennsylvania, and urban drainage flooding was a problem in New Jersey,
Delaware, and extreme southeast Pennsylvania.
A River Flood Statement was issued at 12:42 p.m. EST listing specific stage readings
as of noon. The first Flood Warning which contained stage forecasts was issued at
4:17 p.m. EST for points in Pennsylvania and Delaware. Later, follow-up flood
statements and warnings issued by NWSFO Philadelphia contained current and forecast
stage conditions; however, some of those products did not mention any call-to-action
statements or what would happen to areas near a stream or river as a result of the water
rising to a certain level.
Because of the robust snowmelt, and the rapidity of rises on main-stem rivers, the SH
and other staff members employed the Flood Analysis and River Emulation (FLARE)
program to assess crest levels. The office was also asked by public safety officials for
river stage forecasts. Some FLARE stage estimates were used to assist public safety
officials in short-term planning until MARFC stage forecasts were available. FLARE
was also used to create forecasts for the smaller headwater basins for which NWSFO
Philadelphia is responsible. With fairly accurate WSR-88D precipitation estimates and
ground-truth measurements from IFLOWS, ALERT, and other gaging platforms
ingested into the FLARE program, the output provided the Philadelphia staff with
reasonable stage level forecasts.
Adequate staffing was available to handle the event with the MIC working several
shifts along with the SOO and WCM. Most forecasters were trained to handle this
office's hydrologic responsibility so the SH did not have to handle the entire flood
event. Numerous contacts were handled by phone since many communities and
counties do not receive NWS products directly. Although NWR was used to keep
citizens apprised of the situation, some areas of northwest New Jersey are not covered
by NWR programming.
By early Friday evening, January 19, the precipitation had ended across Philadelphia's
CWFA. Rivers and streams continued to rise from rainfall and snowmelt runoff, and
water from upstream basins. NWSFO Philadelphia continued to issue additional
warnings and statements Friday night and Saturday to extend Flood Warnings or place
other rivers and creeks under warnings. By Friday evening and early Saturday, the
following main-stem rivers were under Flood Warnings: the Christina in Delaware;
Raritan, Passaic, Rockaway, Ramapo, Millstone and Pompton in New Jersey; Lehigh
and Schuylkill in Pennsylvania; and the Lower Delaware. Also under Flood Warnings
were numerous creeks with remote gaging equipment in eastern Pennsylvania,
Delaware, and New Jersey.
Late Saturday night and into Sunday, rivers and creeks had crested and began to
recede. By Sunday afternoon and evening, warnings were canceled for several rivers
as water levels fell below flood stage. The Susquehanna River remained above flood
stage under a Flood Warning through Monday, January 22. All river forecast points
exceeded flood stage with some approaching record stages. No gage problems or
outages were noted.
2.2.5 NWSFO PITTSBURGH, PENNSYLVANIA
Combined area average runoff from rainfall and snowmelt for the Pittsburgh HSA for
the 48-hour period ending 18Z on Friday, January 19, equaled or exceeded normal
January precipitation. Southwest Pennsylvania and east central Ohio had a combined
total of 2.5-3 inches (runoff: 1-1.5 inches; snowmelt: 1.5 inches) while northern
Pennsylvania and the mountains exhibited a combined total ranging from 3-4.5 inches
(runoff: 1.5-2 inches; snowmelt: 2-2.5 inches).
The significant runoff from rainfall and snowmelt, combined with ice jamming,
resulted in flooding which was widespread and which affected all major rivers in the
Upper Ohio River Basin. Flooding was moderate to near record on the Allegheny,
Clarion, Conemaugh, Monongahela, Cheat, Youghiogheny, and Upper Ohio rivers.
The main stems of the Allegheny and Monongahela rivers uncharacteristically crested
in phase, resulting in the maximum possible crest at Pittsburgh.
Personnel at NWSFO Pittsburgh described the Ohio River's response at Pittsburgh as a
"flash flood on a major river." The rate of rise on January 19-20, rivaled the Hurricane
Agnes Flood of 1972 and was markedly erratic due to ice jamming. The crest was
measured at 34.6 feet, nearly 10 feet above flood stage, and was classified by the U.S.
Army Corps of Engineers (COE) as a 75-year flood at Pittsburgh.
River Statements and a Flood Potential Outlook issued by NWSFO Pittsburgh on
Tuesday, January 16, were used effectively to alert the general public, emergency
managers, the media, and other users to the potential for ice flooding at anytime and
the increasing threat of flooding later in the week. Effective call-to-action statements,
such as those listed in the Flood Potential Statement above and the Flash Flood
Warning below, were disseminated throughout the duration of the flooding threat.
Beginning on Thursday, January 18, warmer temperatures, snowmelt, and heavy rain
yielded rapid stream and river rises. NWSFO Pittsburgh responded with flood and
flash flood watch and warning issuances and updates. Rivers rose abnormally fast due
to ice affects at many locations; however, NWSFO Pittsburgh issued river flood
warnings with forecast lead time for major flooding exceeded 10 hours, while the
forecast lead time for crests ranged from 14-33 hours.
2.2.6 NWSFO CHARLESTON, WEST VIRGINIA
Storm total rainfall amounts for January 18-19, 1996, exceeded 1 inch over the
majority of the NWSFO Charleston's HSA with some gages reporting in excess of 1.5
inches. This significant rainfall/runoff, combined with rapid melting of snowpack with
a 2+ inch snow water equivalent over the northeast half of the state, yielded rapid river
and stream rises throughout a significant portion of the HSA. Flooding was widespread
throughout the state as 27 West Virginia counties were declared Federal disaster areas.
Flood Potential Statements issued by NWSFO Charleston on January 16-17, 1996, over
48 hours in advance of the onset of flooding, effectively alerted end users of the
increasing threat of flooding for later in the week.
2.2.7 NWSO WILMINGTON, OHIO
Flooding occurred along several tributaries within the Wilmington HSA during the
period January 18-22. The majority of the tributary flooding occurred during January
18-19, with most locations cresting late on Friday, January 19 and through the early
morning hours on Saturday, January 20. No significant injuries or deaths were
reported in the Wilmington CWA, supporting the collective assessments of their
personnel and end users that dissemination was very effective during the event.
More than 100 river flood warnings and statements were issued during January 17-30.
A Flood Potential Statement was issued at 9:45 a.m. EST on Wednesday, January 17,
highlighting the increasing potential for flooding.
Flood forecasts and statements issued by NWSO Wilmington accurately detailed the
rapidly evolving weather situation and alerted users of the increasing threat of flooding.
Products were concise, informative, and timely, with effective call-to-action
statements. All flood warnings and statements issued by NWSO Wilmington exhibited
a positive lead time. The average lead time for all river flood warnings issued during
the entirety of the event averaged over 9 hours.
2.3 COORDINATION AND DISSEMINATION
On Wednesday, January 17, at 1 p.m. EST, NWSFO Baltimore,
Maryland/Washington, DC, conducted a forecast coordination conference call with the
Commonwealth of Virginia and NWS offices in Wakefield and Blacksburg, Virginia.
Another conference took place at 11 a.m. EST on Thursday, January 18. At that time,
it was decided to prepare for a flood and severe weather event so no special follow-up
briefings would be conducted. However, daily and shift forecast coordination between
each NWS office continued throughout the event. The Washington, DC, Office of
Emergency Preparedness was also briefed on Thursday to confirm that the public works
department was aware that urban and flash flooding would occur Friday, Saturday, and
Sunday.
On Saturday, January 20, at 7:15 p.m. EST, the NWSFOs at both Philadelphia,
Pennsylvania, and Baltimore, Maryland/Washington, DC, coordinated a Flood
Warning for the Maryland portion of the Susquehanna River. With ice jams and
upstream water problems threatening the Conowingo Dam, the Philadelphia Electric
Company, who controls the dam, decided to release water. There was some evacuation
of citizens from Port Deposit, Maryland, in Cecil county, due to high water.
Throughout the flood affected areas, radio and television were the primary sources of
information for most citizens. Most radio and television stations aired watches and
warnings as soon as they received them. Emergency Broadcast System (EBS) radio and
television stations aired watch and warning information beginning Thursday, January
18. The Weather Channel began broadcasting the possibility of flooding across the
northeast United States as early as Tuesday, January 16. Most radio and television
stations receive their weather information from a variety of sources that repackage
NWS warning and forecast information.
With the recent reallocation of forecast areas, NWSFOs have large areas of
responsibility for long-term public products. This requires NWSOs to more effectively
coordinate long-term forecast guidance with NWSFOs. NWSOs in State College,
Pennsylvania, and Binghamton, New York, provide forecast advice through forecast
discussion messages and coordination calls. During this event, both NWSOs were in
full support of the flood watches issued Thursday evening for New York and western
Pennsylvania. During the early morning hours on Friday, both offices strongly urged
NWSFO Philadelphia, Pennsylvania, to issue a flood watch for their CWAs across the
eastern portion of Pennsylvania.
Prior to and during the event, all offices coordinated with the MARFC. Numerous
times, offices requested that the MARFC make adjustments to QPF data, and they
requested new River Forecast information. Forecasters at NWSFOs/NWSOs stayed in
contact with MARFC personnel to keep data updated and corrected, offer suggestions
to the river forecasts, and request new river forecast runs. MARFC was operating 24
hours per day so adequate staffing was available to handle the event. It was discovered
that more coordination prior to the event, and at critical times during the event, may
have helped in making more timely forecast decisions.
NWS offices have multiple telephone lines. Some of these lines should ring directly to
the operations area and not be routed through a voice mail system. There was one
incident where an RFC forecaster could not get in contact with an SH because of the
voice mail system. At least one coordination telephone line not directed through the
voice mail system should be available in the operations area. Backup numbers should
be provided to neighboring NWS offices and public safety officials. NWSFO and
NWSO personnel frequently coordinated with local public safety officials and the
media, mainly by telephone.
Contacts were frequent with other government agencies such as the USGS, COE, state-
level emergency management officials, and state conservation or environmental
divisions. Those agencies noted they had received good support from the NWS offices
and had excellent working relations with them during and before the event. The USGS
stated they received enough lead time to prepare for this event.
There was a good deal of user satisfaction with the efforts provided by NWS offices.
The cities of Harrisburg and Wilkes-Barre, Pennsylvania, received several key
briefings during the event. Critical gage information and discussions of forecast
uncertainty provided to the Luzerne county emergency manager by NWSO Binghamton
resulted in the evacuation of over 100,000 people. The river forecast was within one
half foot of topping a major levee. Constant contact between NWSO State College and
the City of Harrisburg engineers resulted in the evacuation of several hundred people
including the family of the governor of Pennsylvania.
In Pennsylvania, emergency managers in the hardest hit areas were satisfied with
warnings provided by the NWS. NWSO State College has an especially close working
relationship with the Lycoming EMA. The EMA is both very sensitive and
knowledgeable of the flood problems in Lycoming county. Both the NWS and the
EMA have a network of flash flood coordinators within the county for Loyalsock,
Lycoming, Muncy, and Pine creeks, as well as a coordinator for the dikes that protect
the city. This network provides monthly mailings of climatological, stream flow, and
river data including information supplied by the State College office.
In New York, NWSO Binghamton coordinated frequently with the Chemung basin
Flood Warning Service (FWS), obtaining up-to-date information on flood conditions
and valuable precipitation reports (additional information on FWS is located in section
4.2).
Tom Burns, of the West Virginia Office of Emergency Services (OES), described the
flood as "well-predicted" and added the overall dissemination of information to
Emergency Managers and the public was "very good." Mr. Burns also stated he would
like to receive probabilistic guidance as a matter of routine procedure. He thought it
would be very helpful information and would like to "try it out." Burns further stated
that "the shuffled watch and warning responsibilities in the modernized NWS did not
adversely impact OES efforts during the flooding event."
A survey of users, including all Emergency Managers in NWSO Wilmington's CWA,
revealed that all warnings were timely and received without problem. The staff at
NWSO Wilmington felt that coordination with state and local officials as well as the
OHRFC staff was "excellent." A few user issues, however, were articulated by Ohio
State officials during a post-flood meeting in Cincinnati.
Ohio EMA personnel requested a more uniform format of warnings and statements
issued by all NWS field offices in Ohio. The format of warnings from the NWSO
Wilmington is patterned after those issued by the NWS forecast office in Cleveland,
which formerly had HSA responsibility for the entire State of Ohio. Consequently,
Wilmington and Cleveland issue warnings with a similar format, while NWS forecast
offices in Pittsburgh, Pennsylvania, and Charleston, West Virginia, who are
collectively responsible for extreme southeast and eastern Ohio, use a slightly different
product format.
Ohio State officials collectively voiced a strong desire for probabilistic forecast
products. They stated that probabilistic guidance would be of significant benefit in
their decision-making process (i.e., it would have considerable economic benefit).
They articulated a desire for data relating river stage to frequency (i.e., what stage
corresponds to a 10-year flood, a 20-year flood, etc.). They also stated a preference
for "one official NWS voice" for the entire state during flood events to minimize the
amount of required coordination.
NWSO Wilmington also has HSA responsibility for northern Kentucky. A post-flood
gathering of Kentucky officials also addressed the product uniformity issue, further
illustrating the need for improved coordination and resolution of product format
differences. In light of similar concerns by Kentucky State officials, the issue of
product uniformity is clearly a multi-regional issue.
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