SWODY1
SPC AC 181957
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0257 PM CDT TUE MAY 18 2010
VALID 182000Z - 191200Z
...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING OVER
PARTS OF ERN CO...NERN NM...PARTS OF THE OK/TX PNHDLS INTO THE TX S
PLAINS...
...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN CO/WRN KS INTO THE ERN
NM AND WRN INTO N-CNTRL TX...
...CNTRL/SRN HIGH PLAINS...
THE PRIMARY CHANGES TO THE CURRENT FORECAST ARE AS FOLLOWS: 1) A
SLIGHT NWD SHIFT OF THE CATEGORICAL SLIGHT RISK OVER SWRN TX...2) A
SLIGHT EWD SHIFT IN THE CATEGORICAL SLIGHT RISK ALONG THE RED RIVER
VALLEY OF SWRN OK/NWRN TX...3) A SWD EXTENSION OF THE TEN PERCENT
TORNADO PROBABILITY LINE IN THE TX PNHDL...AND 4) THE ADDITION OF A
30 PERCENT PROBABILITY WIND CONTOUR OVER PARTS OF THE OK/TX PNHDLS
INTO WRN OK.
TSTMS ARE EXPECTED TO INCREASE IN AREAL COVERAGE AND INTENSITY
THROUGH THE REMAINDER OF THE AFTERNOON INTO THIS EVENING FROM ERN CO
SWD THROUGH ERN NM INTO THE OK/TX PNHDLS AND WRN TX. HERE...
DIABATIC HEATING COUPLED WITH EWD PROGRESSION OF EML PRECEDING
MIDLEVEL TROUGH AND DEW POINTS IN THE 50S ARE CONTRIBUTING TO AIR
MASS DESTABILIZATION WITH MLCAPE APPROACHING 2000 J/KG BY LATE
AFTERNOON.
AT THE SAME TIME...A 40-50/50-70 KT MID/HIGH-LEVEL JET WILL DEVELOP
EWD THROUGH NM INTO THE SRN HIGH PLAINS...RESULTING IN STEADILY
STRENGTHENING VERTICAL SHEAR. AS SUCH...THE SETUP WILL BECOME
INCREASINGLY FAVORABLE FOR SUPERCELLS CAPABLE OF VERY LARGE HAIL AND
TORNADOES. THE THREAT FOR TORNADOES MAY INCREASE NEAR OR SHORTLY
AFTER 00Z FROM FAR SERN CO SEWD INTO THE OK/TX PNHDLS IN CONCERT
WITH A STRENGTHENING...SELY LLJ.
BY LATE EVENING...STORMS MAY GROW UPSCALE INTO A MCS WITH AN
INCREASED THREAT FOR DAMAGING WINDS OVER THE OK/TX PNHDLS. THE
CONVECTIVE SYSTEM WILL LIKELY BE MAINTAINED OVERNIGHT EWD INTO
OK...SUPPORTED BY STRONG WAA TO THE N OF WARM FRONT RETREATING NWD
INTO NRN TX.
..MEAD.. 05/18/2010
.PREV DISCUSSION... /ISSUED 1119 AM CDT TUE MAY 18 2010/
...CENTRAL AND SRN HIGH PLAINS...
S/W TROUGH CURRENTLY SRN INTERMOUNTAIN REGION MOVES EWD ACROSS SRN
ROCKIES INTO HIGH PLAINS BY 12Z WED. BAND OF STRONGER MID/UPR LEVEL
WINDS ASSOCIATED WITH TROUGH NRN AZ/NM WILL BRING FAVORABLE DEEP
LAYER SHEAR AND LARGE SCALE ASCENT INTO HIGH PLAINS OF CO AND NE NM
BY LATER THIS AFTERNOON. SURFACE RESPONSE TO APPROACHING TROUGH IS
LEE LOW DEVELOPMENT SERN CO WITH ADDITIONAL SMALLER SCALE CYCLONIC
FORMATION TO N OF PALMER DIVIDE.
LOW LEVEL MOISTURE IS SPREADING N/NNW IN 30-40KT LOW LEVEL JET FROM
OK/TX PANHANDLE NWD THRU ERN CO/WRN KS.
WHILE THERE IS CONSIDERABLE UPR CLOUDINESS WITH TROUGH ACROSS
NM...CLEARING LEE OF CO ROCKIES WILL ALLOW GOOD SURFACE HEATING.
WITH REGARDS TO THE MDT RISK...IT NOW LOOKS LIKE THE GREATEST
LIKELIHOOD OF SUPERCELLS WITH LARGE HAIL AND TORNADO POTENTIAL WILL
BE TIED TO THE LOW LEVEL CONVERGENCE VICINITY PALMER DIVIDE SWD THRU
SERN CO/NERN NM INTO NRN TX PANHANDLE VICINITY AND N OF MID LEVEL
WIND MAX CURRENTLY CROSSING NRN NM.
INITIAL DEVELOPMENT EXPECTED IN ERN CO WHERE CINH WILL WEAKEN BY MID
AFTERNOON. THEN EXPECT TO CONTINUE TO SEE AT LEAST SCATTERED STORMS
INCLUDING SUPERCELLS SWD FAR ERN NM WHICH IS WHERE THE DRY LINE
SHOULD HAVE MIXED EWD TO BY LATER THIS AFTERNOON.
WITH LAPSE RATES IN EXCESS OF 8C/KM...MLCAPES TO 1500 J/KG AND
FAVORABLE VEERING HODOGRAPHS...CONDITIONS APPEAR FAVORABLE FOR VERY
LARGE HAIL/TORNADOES WITHIN THE MDT AREA THAT WILL SHIFT EWD BY
EARLY EVENING INTO SWRN KS SWD THRU THE TX PANHANDLE.
FURTHER S WITH SOMEWHAT LESS FAVORABLE LAPSE RATES AND TO THE S OF
THE LARGE SCALE ASCENT WITH THE TROUGH AND SOMEWHAT RETARDED SURFACE
HEATING DUE TO OBSERVED MID LEVEL CLOUDS...STORMS WILL BE MORE
WIDELY SCATTERED AND DEVELOP LATER AS WELL. HOWEVER ISOLATED
SUPERCELLS ARE STILL LIKELY WITH POTENTIAL FOR PRIMARILY LARGE HAIL
AS THEY PROPAGATE/MOVE EWD DURING THE EVENING.
...MT AND ADJACENT NORTHERN HIGH PLAINS THIS AFTN/EARLY EVE...
MOISTURE WILL INCREASE TODAY OVER THE HI PLNS OF ERN MT...WITH PW
RISING TO AOA .75 INCHES AS LEE SIDE TROUGH STRENGTHENS. TSTMS
SHOULD FORM THIS AFTN ALONG THE TROUGH AND/OR ALONG TERRAIN-INDUCED
CIRCULATIONS AS HEATING BOOSTS SBCAPE TO 500-1000 J/KG /HIGHEST
ACROSS SE MT/. COUPLED WITH MODEST...DEEP...S TO SSELY FLOW AND
STEEP LOW TO MID LVL LAPSE RATES...SETUP MAY SUPPORT A FEW SMALL
CLUSTERS STG/SVR STMS. HAIL SHOULD BE THE MAIN THREAT.
...FL THIS AFTN...
SLIGHT COOLING/ASCENT WITH CYCLONIC MID/UPR LVL FLOW MAY
CONTRIBUTE TO THERMODYNAMIC PROFILES FAVORABLE FOR ISOLD
STRONG/SVR TSTMS THIS AFTN. A FEW DOWNBURSTS/MARGINALLY
SVR HAIL WILL BE POSSIBLE...MAINLY ALONG THE E CST SEA BREEZE FRONT.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.
No comments:
Post a Comment