SWODY1
SPC AC 121604
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1104 AM CDT SAT MAY 12 2007
VALID 121630Z - 131200Z
..THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF NERN ORE INTO
PORTIONS OF WRN/NRN MT...
..NRN INTERMOUNTAIN REGION ACROSS THE NRN ROCKIES...
MID LEVEL VORT MAX/UPPER LOW NOW CENTERED NEAR 44N/126W IS MOVING
NEWD AND WILL MOVE ACROSS THE PAC NW TODAY IN THE FORM OF A
POSITIVELY-TILTED SHORTWAVE TROUGH. ASSOCIATED PACIFIC COLD FRONT
WILL PUSH EWD ACROSS THE NRN ROCKIES BY TONIGHT. WEAK SURFACE LOW
CENTERED NEAR BOI AT 15Z IS EXPECTED TO SHIFT STEADILY ENEWD AND
UNDERGO SOME DEEPENING DURING THE LATTER HALF OF THE PERIOD INTO
CENTRAL MT.
AIR MASS ACROSS MUCH OF THE INTERMOUNTAIN REGION INTO THE NRN
ROCKIES REMAINS RATHER DRY WITH PW/S AROUND .5" AT BOI AND OTX THIS
MORNING...AND SURFACE DEW POINTS FROM THE UPPER 30S TO MID 40S.
HOWEVER...STEEP LAPSE RATES AND SUFFICIENT MID LEVEL MOISTURE IS IN
PLACE FOR AN AREA OF MARGINAL MLCAPE WITH ROBUST AFTERNOON HEATING.
IN ADDITION...DEEP LAYER SHEAR WILL STRENGTHEN THROUGH THE DAY AS
50+ KT H5 JET DEVELOPS NEWD ACROSS ORE AND INTO THE NRN ROCKIES LATE
TODAY AND TONIGHT. GIVEN EXPECTED DESTABILIZATION AND INCREASED
DEEP ASCENT...STORMS SHOULD DEVELOP INVOF SURFACE COLD FRONT AND
OVER HIGHER TERRAIN FROM PORTIONS OF CENTRAL ORE NEWD INTO WRN MT
THIS AFTERNOON AND EVENING. EAST OF THE DIVIDE...LOW LEVEL MOISTURE
IS GREATER WITH SURFACE DEW POINTS AROUND 50F LIKELY SURVIVING
STRONG AFTERNOON BOUNDARY LAYER MIXING. THIS IS FORECAST TO SUPPORT
MODERATE INSTABILITY WITH MLCAPE FROM 1500-2000 J/KG AND LITTLE OR
NO CAPPING BY EARLY THIS EVENING ACROSS PART OF WRN/CENTRAL MT.
CAPPING WILL LIKELY SUPPRESS DEVELOPMENT OVER SRN MT. EFFECTIVE
BULK SHEAR WILL BE SUPPORTIVE OF SUPERCELLS AND ORGANIZED
LINES/CLUSTERS AS THIS ACTIVITY SPREADS ENEWD THROUGH THE MID TO
LATE EVENING. LARGE HAIL AND DAMAGING WINDS COULD ACCOMPANY
STRONGER CELLS...WITH A SLIGHTLY INCREASED SEVERE POTENTIAL INTO
WRN/N-CENTRAL MT LATER TODAY GIVEN THE GREATER INSTABILITY.
..SERN U.S AND LOWER MS RIVER VALLEY INTO THE DELMARVA...
SIMILAR TO THE PAST COUPLE DAYS...A LARGE AREA OF MODERATE
INSTABILITY IS EXPECTED TO DEVELOP BY THE EARLY AFTERNOON OVER THIS
AREA GIVEN ABUNDANT LOW LEVEL MOISTURE AND STRONG HEATING. SHEAR
AND LAPSE RATES WILL REMAIN QUITE WEAK AND SUPPORT
SHORT-LIVED/PULSE-TYPE THUNDERSTORMS PRODUCING ISOLATED LARGE HAIL
AND DAMAGING WINDS. ACTIVITY WILL REMAIN STRONGLY DIURNALLY DRIVEN
AND WEAKEN AFTER SUNSET. EXCEPTION WILL BE NEAR SURFACE COLD FRONT
PUSHING SWD OUT OF THE MID ATLANTIC...WHERE INSTABILITY WILL BE
MARGINAL BUT BE OFFSET BY STRONGER SHEAR. ACROSS THIS AREA...STORMS
MAY BE A BIT LONGER-LIVED THOUGH SEVERE THREAT SHOULD REMAIN
MARGINAL GIVEN THE LIMITED INSTABILITY.
..MN...
NOCTURNAL THUNDERSTORM DEVELOPMENT WILL LIKELY BE A BIT MORE ROBUST
AND FARTHER NE THAN STORMS SATURDAY NIGHT...ALONG NOSE OF 40+ SWLY
LLJ. MODELS ARE CONSISTENT IN INCREASING ELEVATED THUNDERSTORMS
AFTER 06Z ACROSS FAR ERN SD/SERN ND INTO WRN/CENTRAL MN...WHERE
MUCAPE COULD APPROACH 1500 J/KG. STRONG EFFECTIVE SHEAR AOA 50 KT
SHOULD SUPPORT THE POTENTIAL FOR ROTATING UPDRAFTS AND A THREAT OF
HAIL /SOME OF IT MARGINALLY SEVERE/ WITH THE STRONGER CORES.
.EVANS/LEVIT.. 05/12/2007
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@PO.UIUC.EDU with
"unsub wx-storm" in the body of your message. For more information write chris@lib.siu.edu.
No comments:
Post a Comment