BAMEX Daily Notes

The following are short summaries of daily activites
 at the BAMEX Operations Center (Mid America Airport)

 

Wednesday - May 21, 2003 - The NOAA P3 and Navy P3 were ready to go.  However the mechanism releasing the dropsondes continued to perform poorly.  Additional testing would be needed.  Testing of the microphysical probles on the NOAA P3 are planne for Thursday. Forecasters were looking to Saturday for a potential mission.  Mark Ratzer (Lead Forecaster at WFO Chicago) joined Ron Przybylinski for the afternoon and early evening nowcast shift.
 

Friday - May 23, 2003 -  Both the NOAA P3 and the Navy P3 were ready to go for the next mission.  Additional testing was performed this afternoon with the dropsondes associated with the High-Altitude Jet.  The MIPS, Mobile Sounders and mesonet vehicles were stationed over north-central Oklahoma for possible interception of convection.  Some testing of the radiosondes were completed with the mobile sounder vehicles.  The forecast team and mission scientists scrubbed today's mission for a better opportunity across the central and southern plains Saturday afternoon.    There was some worry about an MCS developing over the Nebraska Panhandle or Central Nebraska overnight.  The MM5 was forecasting a large MCS over west-central Nebraska this evening while the WRF model did not suggest such development.
 

Saturday - May 24, 2003 - The first Mesoscale Convective Vortex Mission was underway by late morning. An asymmetic MCS moved across  northeast Oklahoma during the mid to late morning hours.  Isolated damaging winds occurred with a small bowing segment associated with the MCS.  The Lear Jet (High-Altitude Jet) took off first at 11:00 am cdt while the NRL P3 left Mid-America Airport at 12 noon.  The NOAA P3 took off one hour later.  The NRL P3 traveled mainly along the leading edge of the MCV while the NOAA P3 completed a sprial type descent around the vortex core from 18000 - 500 feet.  The NOAA P3 was descending about 1 m/s and simulating a falling snowflake.  The descent was faster once they reached the freezing level.  They simulated a falling raindrop below the freezing level.  Mark Ratzer (WFO Chicago) and I assisted the operation's director  in vectoring the NOAA P3 to the center of the MCV.  We hit it quite well - right on target over north-central Arkansas (50 km SSE of Harrison Arkansas (HRO).   The NOAA P3 folks were happy campers.  We also assisted the mission's director in making 1, 2 and 3 hour forecast projections of the MCV center.  The high-altitude jet released about 30 dropsondes surrounding and within the MCV center.  This was one of the most sampled MCVs in recent years.  Mark and I provided nowcasts to the operation's director about every 1.5 to 2.0 hours.  You can find our nowcasts in the BAMEX Cataloge (Reports). We were projecting new convective development along the Red River later in the afternoon, since the old outflow boundary from the morning convection extended WNW-ESE over this area.  Surface dewpoints were also pooling in this area. The VICI wind profiler time-height cross-section proved to be very useful in showing very little vertical wind shear for much of the afternoon across west-central Oklahoma except after 2300 UTC.  In contrast, the Palentine Texas wind profiler time-height cross-section showed moderate shear (15-16 m/s) for much of the afternoon.  We expected convection to fire along the old weak outflow boundary across far southern and southeast Oklahoma by 22-23 UTC.  In contrast, supercells formed over northeast Texas, approximately 100 km east of DFW area in the area of stronger shear and higher instability.   This system was too far on the fringe of the BAMEX domain.  Thus the planes landed back at Mid-America airport late Saturday afternoon.
 

Tuesday, May 27, 2003 -  Bob Johns from CIMMS/CAPS (retired SPC) continues to brief the group on the latest forecasts.   He is predicting the potential for a operations Wednesday afternoon and even across northeast part of the BAMEX domain (Illinois...Indiana).  We are expecting thunderstorm activity to develop in the early afternoon over Wisconsin and move southeastward across Illinois and Indiana.  The biggest problem is the lack of instability (only expecting CAPES of 1000 - 1500 J/Kg).  The ferry for the P3's would be relatively short.  Chris and Morris set the clock for a noon takeoff for the NRL P3 and a 1:00 pm takeoff for the NOAA P3.  We would plan to place the Ground-Based systems somewhere in south-central Illinois.
 

Wednesday, May 28, 2003 -  Dan Baumgardt (SOO from WFO LaCrosse WI) joined the BAMEX Nowcast group.   Based on the lastest thinking from the forecast - nowcast group convection should form over northern Illinois - east-central Iowa by midday.  Current convection over central Wisconsin should intensify as the afternoon continues.  The biggest problem with today's scenario is the degree of instability - we were only expecting MUCAPE values of 1000 - 1500 J/Kg across parts of central and southern Illinois.  Magnitudes of the vertical wind shear with this system ranged from 35 to 40 kts over the area of study.  By mid morning we placed the GBOS group over south-central Illinois.   We were expecting a convective complex to form over northwest Illinois and travel southeastward across central and southern Illinois and into parts of southwest Indiana.   Between noon and 1:00 PM isolated convective cells formed over the Quad Cities area.  They intensified and moved south-southeastward across central Illinois between 3:00 and 4:00 pm.  The convective cells continued to remain discrete with the roots of the updrafts on the upshear side (northwest side) rather than the downshear side.   One supercell within the complex formed over central Illinois (north of Lincoln IL) spawned tornadoes and produced golfball hail.  This supercell continued to produce golfball size hail across parts of Christan and Shelby counties in Illinois.  Mark Ratzer and I continued to generate nowcasts about every 90 minutes - focusing on current location of convection, convective trends and timing as to when this system would move near GBOS.   We also assisted the NRL and NOAA P3's concerning timing of the Wisconsin system. Between 2:00 and 3:00 pm a mini-supercell moved across Kankakee county Illinois and generated a low-level boundary oriented northwest-southeast.  Isolated to scattered convection formed along this boundary during the next 1 to 2 hours.  The convective complex from southern Wisconsin intensified and produced a stratiform rain-region along the system's trailing flank as it entered northeast Illinois.  A bowing segment was noted with this system and produced damaging winds over parts of Will and Kankakee counties.  The NRL P3 first flew along the leading edge of the central Illinois convective system.  However, discrete storms persisted, thus they abandoned this system and flew north-northeast to the MCS over northeast Illinois. Their flight altitude remained relatively low at 5000 ft agl.  Their mission is to observe the storm reflectivity and velocity structures along the leading edge of the mature MCS.  They experienced problems in flying along the leading edge of the mature MCS due to the intensifying scattered convection along the old outflow boundary.  In contrast, the NOAA P3 was very successful in surveying the trailing flank of the MCS over northeast Illinois.   The high-altitude Lear Jet released a number of dropsondes on both convective systems.  This event was quite challenging in many respects: 1) when would convective mode change if at all with the central Illinois system, 2) forecasters and nowcasters were not expecting the development of an organized MCS over northeast Illinois, and 3) the scattered convection along the old outflow boundary from the mini-supercell proved to be a problematic.  In contrast, the timing of the central Illinois convective system reaching GBOS over southern Illinois proved to be very successful.   The GBOS group was given a 5 to 6 hour leadtime as to when the convective complex would reach them.   By late afternoon the scattered convection associated with the old outflow boundary merged with the progressive bowing segment as it traveled across far east-central Illinois and west-central Indiana.  Both the NRL P3, NOAA P3 and high-altitude jet continued to collect Doppler data and released dropsondes beyond 6:00 PM CDT with the northeast Illinois QLCS.  The NOAA P3 conducted a spiral descent (1 m/s) simulating a falling snowflake within the startiform rain region of the MCS.  They increased their spiral descent below the freezing level.  The stratiform rain region behind the leading convective line appeared to cycle a few times between 2200 - 0200 UTC. This was quite interesting, and different compared to a nearly continuously stratiform rain region found in more organized MCSs. The Lear Jet was the first aircraft to return to Mid-America.  Both P3's returned to Mid-America between 0000 and 0200 UTC.