SPC AC 162147
DAY 1 CONVECTIVE OUTLOOK AMEND 1
NWS STORM PREDICTION CENTER NORMAN OK
0447 PM CDT SUN MAY 16 2010
VALID 162000Z - 171200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS OK/N TX/AR AND INTO SWRN
TN/NRN MS...
AMENDED TO EXPAND SLIGHT RISK ACROSS THE MS VALLEY INTO SWRN TN/NRN
MS
...SWRN TN/NRN MS...
HAVE EXPANDED THE SLIGHT RISK OVER AR EWD ACROSS THE MS VALLEY AND
INTO SWRN TN AND NRN MS...AS WIDESPREAD STORMS MOVING ACROSS AR WILL
LIKELY MOVE E OF THE RIVER OVER THE NEXT COUPLE OF HOURS. WITH 1000
TO 2000 J/KG MIXED-LAYER CAPE AHEAD OF THE STORMS...SEVERE POTENTIAL
-- MAINLY IN THE FORM OF LARGE HAIL -- WILL LIKELY CONTINUE OVER THE
NEXT SEVERAL HOURS.
...N TX/OK EWD INTO AR/NRN LA...
CONVECTION HAS DEVELOPED ACROSS PARTS OF OK AND THE ERN TX PANHANDLE
THIS AFTERNOON...SOUTHEAST OF A VORT MAX MOVING INTO CENTRAL KS.
STRONGEST STORMS ARE MOVING INTO CENTRAL OK ATTM...WHERE MODERATE
INSTABILITY AND AMPLE SHEAR HAS YIELDED A LARGE SUPERCELL.
OTHER/ISOLATED ROTATING STORMS WILL LIKELY DEVELOP ACROSS THIS
REGION...POSING A THREAT FOR VERY LARGE HAIL...LOCALLY-DAMAGING
WINDS...AND PERHAPS A BRIEF TORNADO. CONVECTION SHOULD SPREAD SEWD
WITH TIME...PERHAPS AFFECTING ERN OK/N TX LATER THIS EVENING BEFORE
CONVECTION BEGINS TO SLOWLY DIMINISH IN INTENSITY.
FARTHER E...STORMS HAVE DEVELOPED ACROSS WRN AND CENTRAL AR...AHEAD
OF A LARGER VORT MAX MOVING ACROSS ERN KS/ERN OK INTO WRN MO/AR.
STRONGEST STORM ATTM IS JUST NW OF LITTLE ROCK...AND GIVEN
SUPERCELLULAR CHARACTERISTICS EXPECT LARGE HAIL WITH THIS STORM.
GIVEN MODERATE INSTABILITY INDICATED ACROSS THIS AREA ALONG WITH
SHEAR SUFFICIENT FOR MID-LEVEL ROTATION...ADDITIONAL SEVERE STORMS
WILL LIKELY EVOLVE THIS AFTERNOON AND EVENING...WITH THREAT FOR
LARGE HAIL AND LOCALLY-DAMAGING WINDS TO CONTINUE.
...THE SOUTHEAST...
A LARGE AREA OF SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED
ACROSS THE SOUTHEAST...WHERE 500 TO 1500 J/KG MIXED-LAYER CAPE IS
NOW INDICATED. WHILE DEGREE OF INSTABILITY WILL BE SUFFICIENT TO
SUPPORT A FEW STRONGER CELLS...OVERALL SHEAR REMAINS MODEST...AND
THUS SEVERE THREAT LIKEWISE REMAINS LIMITED. WHILE A FEW STRONGER
MULTICELL STORMS/CLUSTERS MAY PRODUCE MARGINALLY-SEVERE HAIL/WIND
GUSTS...THREAT DOES NOT APPEAR TO WARRANT UPGRADE TO SLIGHT RISK.
...ORE/SRN WA...
MODEST DESTABILIZATION IS UNDERWAY ACROSS PARTS OF WA/ORE AS HEIGHT
FALLS BEGIN OVERSPREADING THIS AREA. CU DEVELOPMENT IS EVIDENT OVER
THE OREGON CASCADES...AND SHOULD INCREASE ACROSS THIS REGION LATER
THIS AFTERNOON. INCREASING MID-LEVEL FLOW MAY PROVIDE AMPLE SHEAR
FOR SOME UPDRAFT ORGANIZATION...AND THUS WILL MAINTAIN
LOW-PROBABILITY HAIL/WIND THREAT ACROSS THE REGION LATER THIS
AFTERNOON AND EVENING.
..GOSS.. 05/16/2010
.PREV DISCUSSION... /ISSUED 1122 AM CDT SUN MAY 16 2010/
...SRN PLAINS...
WEAK UPPER LOW SWRN NEB WITH TROUGH SWD TO TX PANHANDLE CONTINUES
ESEWD TO LWR MO/MS VALLEY BY 12Z MON. LITTLE IN THE WAY OF SURFACE
REFLECTION OF TROUGH AS LOWER TROP FLOW GENERALLY WEAK OVER MUCH OF
TX/OK. HOWEVER WITH THE RELATIVELY COLD/STEEP MID LEVEL LAPSE RATES
ACCOMPANYING UPPER SYSTEM AND MOIST BOUNDARY LAYER...WHERE HEATING
CAN OCCUR THUNDERSTORMS WILL BE ABLE TO DEVELOP BY MID AFTERNOON AS
TEMPS RISE TO 80F OR ABOVE.
THERE IS A SURFACE BOUNDARY EXTENDING FROM DECAYING MCS OVER SRN KS
SWWD THRU FAR NWRN OK AND ACROSS THE TX PANHANDLE. LOOK LIKE CLOUDS
WILL HOLD IN ALONG KS/OK BORDER WHILE CURRENTLY MUCH OF WRN OK
HEATING UP WELL. THUS FOCUS FOR ORGANIZED THUNDERSTORMS EXPECTED TO
DEVELOP E/SE ACROSS MUCH OF NRN/CENTRAL OK THIS AFTERNOON ASSOCIATED
BOTH WITH THE LOW LEVEL CONVERGENCE WITH THE SEWD MOVING BOUNDARY
AND THE ZONE OF DIFFERENTIAL HEATING TAKING PLACE S OF KS/OK BORDER.
WITH ABOUT 30KT OF DEEP LAYER SHEAR AND MLCAPES AOA 2000 J/KG STORM
MODE INITIALLY MULTICELL VICINITY BOUNDARIES...BECOMING MORE LINEAR
LATER THIS AFTERNOON/EVENING. LARGE HAIL WILL BE PRIMARY THREAT
GIVEN THE COOL/STEEP MID LEVEL LAPSE RATES WITH SOME WIND DAMAGE
CONCERN AS STORMS BECOME MORE OUTFLOW DOMINATED. HAVE SHIFTED THE
EARLIER HIGHER HAIL PROBS NEWD BASED ON THE ABOVE SCENARIO.
FURTHER S AND E ACROSS AR AND TX...STORMS SHOULD BECOME COMMON BY
MID/LATE AFTERNOON AS CINH DISSIPATES MUCH OF AREA. HOWEVER LACK OF
FOCUS AND WEAK SHEAR MAKES IT DIFFICULT TO PINPOINT AN AREA OF AN
ORGANIZED SEVERE THREAT. HOWEVER LARGE HAIL AND BRIEF DAMAGING WINDS
WILL BE POSSIBLE IN THE STRONGER STORMS GIVEN ADEQUATE SHEAR AND MID
LEVEL LAPSE RATES AROUND 7C/KM.
...SERN STATES...
STRONG STORMS WILL FORM WITH DAYTIME HEATING ALONG/S OF THE RESIDUAL
FRONTAL ZONE/SFC LOW OVER REGION. MODEST DEEP SHEAR AND MOIST
ENVIRONMENT MAY SUPPORT UPSCALE DEVELOPMENT INTO BANDS/SMALL
CLUSTERS WITH LOCALLY DMGG WIND/MARGINALLY SVR HAIL.
WILL MAINTAIN MARGINAL SEVERE PROBABILITIES GIVEN LIMITED SHEAR AND
MID LEVEL LAPSE RATES LESS THAN 7C/KM.
...ORE/SRN WA...
SUBSTANTIAL HEIGHT FALLS WILL OVERSPREAD THE PACIFIC NORTHWEST LATER
TODAY/TONIGHT AS MULTIPLE MID LVL IMPULSES CROSS REGION AHEAD OF
AMPLIFYING OFFSHORE TROUGH. SUFFICIENT MOISTURE/ INSTABILITY AND
MODERATELY STRONG/LARGELY UNIDIRECTIONAL SSW WIND FIELD MAY YIELD
SOME STRONG/SVR TSTMS WITH HAIL/GUSTY WINDS VICINITY ORE CASCADES BY
LATER THIS AFTERNOON...SPREADING NWD TO WA CASCADES THIS EVENING.
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
|
