Thursday, April 22, 2010

Upcoming Severe Weather Threat


Significant Tornado Parameter >=5, Saturday at 7 p.m.

Excerpts from National Weather Service Area Forecast Discussions this morning:

HUNTSVILLE

THE ATMOSPHERE WILL DESTABILIZE RAPIDLY ON SATURDAY AS A STRONG LLJ /50-60KT/ BARES DOWN ON THE VALLEY...AND SUPERCELLS WILL DEVELOP THROUGH THE AFTERNOON HOURS. BULK SHEAR...LOW LEVEL HELICITY...AND INSTABILITY SUGGEST TORNADOES...DAMAGING WINDS...AND LARGE HAIL WILL BE POSSIBLE FROM THESE STORMS ON SATURDAY /ESPECIALLY IN THE WESTERN TWO-THIRDS OF THE CWFA

BIRMINGHAM, AL

BUT ALL SEVERE THREATS APPEAR TO BE IN THE CARDS. WHILE MOST OF THE UPPER PROFILES REMAIN SATURATED...IT DOES LOOK LIKE THE UPPER LAPSE RATES ARE STEEP ENOUGH TO CONTINUE TO INCLUDE A DAMAGING WIND AND LARGE HAIL THREAT FOR THE MORE ROBUST CELLS. MEANWHILE...THE LOWER LEVEL TURNING AND STRENGTHENING WIND FIELDS WILL BE SUPPORTIVE OF TORNADOES...INCLUDING THE THREAT FOR SOME STRONG AND LONG-LIVED TORNADOES. WE WILL NEED TO FOCUS THE ATTENTION EARLY JUST UPSTREAM FOR CELLS THAT FORM IN CENTRAL MS AND MOVE INTO WESTERN SECTIONS OF THE CWA...HOWEVER... IT IS STARTING TO LOOK MORE AND MORE LIKE WE WILL HAVE OUT OWN CELL DEVELOPMENT BY THE MIDDLE AFTERNOON AND EVENING HOURS.

JACKSON, MS

NUMEROUS SVR STORMS ARE EXPECTED TO BREAK OUT BETWEEN 5AM AND MID/LATE MORNING. IT APPEARS THE GREATEST RISK FOR SAT WILL BE FROM 5 AM TO 2PM. MULTIPLE SUPERCELLS ARE EXPECTED WITH A COUPLE CLUSTERS OF STORMS DEVELOPING. INSTABILITY WILL BE SOLID WITH MLCAPE IN THE 1500 J/KG RANGE. LOW LEVEL SHEAR WILL BE STRONG TO THE NOCTURNAL LL JET AND JUST THE PLAIN RESPONSE TO THE INTENSE SYSTEM APPROACHING. CONDITIONS WILL EXIST FOR A SIGNIFICANT SEVERE EVENT. IT APPEARS THAT THE STRONGEST TORNADO INGREDIENTS AND MOST FAVORABLE TIME FOR TORNADOES WILL BE BETWEEN 5-11AM. SUCH PARAMETERS WILL SUPPORT THE CHANCE FOR A FEW STRONG TORNADOES. IN ADDITION...QUARTER TO GOLF BALL WILL BE POSSIBLE WITH ANY STORM ALONG WITH DM WINDS. BY MID/LATE MORNING AND INTO THE AFTERNOON...THE MOST INTENSE FORCING WILL MOVE IN ALONG WITH A MID LEVEL DRY PUNCH. THIS LOOKS TO DRIVE A INTENSE SQUALL LINE. DM WINDS...SOME HIGH END...WILL BE POSSIBLE ALONG WITH TORNADOES AND HAIL WITH ANY BOWING SEGMENT. BY 3-7 PM...ACTIVITY SHOULD PUSH EAST AND THEN OUT OF THE AREA IT IS NOT OFTEN ONE FEELS CONFIDENT IN USING SUCH STRONGLY WORDED STATEMENTS IN A FORECAST. HOWEVER...THIS CASE SEEMS TO FIT AS ALL INDICATIONS...ALONG WITH LOCAL SVR WEATHER CHECKLIST OUTPUT...SUPPORT A HIGH END/SIGNIFICANT EVENT. WHILE THERE MAY BE LIMITING FACTORS...THERE ARE NOT MANY.

...

No comments: