National Weather Service United States Department of Commerce

Potential Tornado Outbreak Today; Atmospheric River for the Northwest

Severe thunderstorm outbreak with tornadoes, wind damage, and large hail are expected today from parts of the southern Plains, eastward into the lower Mississippi Valley and central Gulf Coast states. Several long-track strong tornadoes are expected. Furthermore, excessive rainfall potential exists with flash flooding possible. For the western US, heavy precipitation and strong winds continue. Read More >

 

 

Wednesday March 25, 2015

...PENNSYLVANIA SEVERE WEATHER AWARENESS WEEK...

THIS IS SEVERE WEATHER AWARENESS WEEK IN PENNSYLVANIA.

NOW IS THE TIME TO PREPARE FOR THE UPCOMING SEVERE WEATHER SEASON.

WE ARE COVERING A DIFFERENT SAFETY TOPIC EACH DAY OF THIS WEEK.

OUR SEVERE WEATHER AND WEATHER SAFETY TOPIC FOR TODAY IS...
FLASH FLOODING AND FLASH FLOOD SAFETY.

MORE PEOPLE ARE KILLED BY FLASH FLOODS THAN BY OTHER STORM-RELATED
WEATHER HAZARDS. UNFORTUNATELY...MOST PEOPLE SUCCUMB TO FLOODING
AFTER THEY DRIVE THEIR AUTOMOBILES INTO FLOODED ROADWAYS AND ARE
SUBSEQUENTLY SWEPT AWAY TO THEIR DEATHS.

IF YOU ENCOUNTER A FLOODED ROADWAY...TURN AROUND...DON'T DROWN! 
FIND ANOTHER ROUTE...IT COULD SAVE YOUR LIFE! MANY PEOPLE LOSE
THEIR LIVES BY NOT ADHERING TO THIS SIMPLE RULE...
TURN AROUND...DON'T DROWN!

WHAT IS A FLASH FLOOD?

A FLASH FLOOD IS A RAPID FLOOD.
DURING A FLASH FLOOD...A STREAM OR CREEK WILL RISE RAPIDLY AND
CREST GENERALLY WITHIN A FEW HOURS OF THE START OF THE HEAVY RAIN.
FLASH FLOODS ARE SO DANGEROUS BECAUSE THE WATERS RISE SO
QUICKLY THAT THEY CAN CATCH PEOPLE OFF GUARD AND TRAP THEM IN
PRECARIOUS SITUATIONS. THIS IS WHY THE NATIONAL WEATHER SERVICE
CONSTANTLY MONITORS RAINFALL USING RAIN GAUGES AND RADAR
ESTIMATES...AS WELL AS MONITORING STREAM AND CREEK LEVELS 
USING AUTOMATED RIVER GAUGES AND LOCAL SPOTTERS. YOUR NATIONAL
WEATHER SERVICE WILL ISSUE FLASH FLOOD WATCHES AND WARNINGS
TO HELP ALERT YOU TO EXPECTED FLOOD DANGERS.

WHAT CAUSES FLASH FLOODS?

FLASH FLOODS ARE CAUSED WHEN VERY HEAVY RAINFALL...USUALLY FROM
SLOW-MOVING THUNDERSTORMS...OVERWHELMS THE NATURAL OR MAN-MADE
DRAINAGE SYSTEMS. STREAMS...CREEKS AND SMALLER RIVERS ARE MOST
VULNERABLE TO FLASH FLOODING. FLASH FLOODING OCCURS IN URBAN
AREAS AS WELL AS IN RURAL AREAS.

WHAT DOES A FLASH FLOOD WATCH MEAN?

A FLASH FLOOD WATCH MEANS THAT THE POTENTIAL EXISTS FOR FLASH
FLOODING TO OCCUR ON ANY STREAM...CREEK OR SMALL RIVER. THE WATCH
DOES NOT MEAN THAT FLOODING IS IMMINENT OR OCCURRING. IT JUST MEANS
THAT IT IS A POSSIBILITY.

WHAT YOU SHOULD DO WHEN A FLASH FLOOD WATCH IS ISSUED...

BE PREPARED TO TAKE QUICK ACTION TO PROTECT YOURSELF BY MOVING TO
HIGHER GROUND IF YOU ARE NEAR A WATERWAY. WATCH WATER LEVELS
CAREFULLY AND BE READY TO EVACUATE AT ANY MOMENT. IF YOU ARE
TRAVELING DURING A FLASH FLOOD WATCH...BE ALERT FOR SIGNS OF FLASH
FLOODING...ESPECIALLY AT NIGHT WHEN IT CAN BE DIFFICULT TO SEE A
FLOODED ROADWAY. BE VERY CAREFUL IF DRIVING THROUGH FLOOD PRONE
AREAS...AND IF YOU ENCOUNTER A FLOODED ROADWAY...
TURN AROUND...DON'T DROWN.
FIND AN ALTERNATE ROUTE. IT COULD SAVE YOUR LIFE!

WHAT DOES A FLASH FLOOD WARNING MEAN?

A FLASH FLOOD WARNING MEANS RAPID LIFE-THREATENING FLOODING IS
OCCURRING...OR WILL BEGIN VERY SOON. A WARNING LETS YOU KNOW THAT
HEAVY RAIN WILL CAUSE THE WATER TO RISE AND OVERFLOW THE BANKS OF
THE WATERWAYS NEARBY. A FLASH FLOOD WARNING CAN ALSO BE PROMPTED BY
LEVEE AND DAM FAILURES. YOU NEED TO TAKE ACTION IMMEDIATELY TO
PROTECT YOUR LIFE AND PROPERTY IF YOU ARE IN THE DANGER AREA.

WHAT SHOULD YOU DO WHEN A FLASH FLOOD WARNING IS ISSUED?

MOVE UP TO HIGHER GROUND IMMEDIATELY AND GET OUT OF THE DANGER AREA.
NEVER DRIVE ACROSS BRIDGES COVERED WITH WATER...OR THROUGH AREAS
WHERE WATER COVERS THE ROADWAY.  MOST CARS WILL FLOAT IN JUST 16 TO
18 INCHES OF WATER. IF RISING WATER CAPTURES YOUR AUTOMOBILE...IT
COULD EASILY SWEEP YOU AWAY. BE ESPECIALLY CAUTIOUS AT NIGHT...WHEN
IT IS HARDER TO RECOGNIZE THAT AN AREA MAY BE FLOODED.

FOR ADDITIONAL INFORMATION ON FLASH FLOODS AND SEVERE WEATHER...
CHECK OUT THE NATIONAL WEATHER SERVICE WEB SITE AT:

https://weather.gov

OUR WEATHER SAFETY TOPICS FOR THE REST OF THE WEEK WILL BE...
THURSDAY...RIVER FLOODING SAFETY.
FRIDAY...SKYWARN SEVERE WEATHER SPOTTERS.