SPC AC 041630
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CDT MON JUN 04 2007
VALID 041630Z - 051200Z
...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY
TONIGHT FROM THE SRN HIGH PLAINS EWD ACROSS THE GULF COAST TO THE SE
ATLANTIC COAST...
...SRN HIGH PLAINS THIS AFTERNOON/EVENING...
AGAIN THIS AFTERNOON...CONVECTION WILL LIKELY FORM OVER THE HIGHER
TERRAIN IN SE CO/ERN NM AND MOVE GENERALLY SSEWD OVER THE ADJACENT
HIGH PLAINS. A SERIES OF DIFFUSE SPEED MAXIMA IN THE NWLY FLOW
REGIME MAY ENHANCE STORM COVERAGE OVER NE NM...WHILE INSTABILITY AND
VERTICAL SHEAR WILL BE SUFFICIENT FOR SOME STORMS WITH SUPERCELL
STRUCTURE. LARGE HAIL SHOULD BE THE MAIN SEVERE THREAT...THOUGH AN
ISOLATED TORNADO CANNOT BE RULED OUT DURING THE AFTERNOON. DAMAGING
WINDS WILL ALSO BE POSSIBLE...ESPECIALLY WITH ANY STORM MERGERS THAT
RESULT IN UPSCALE GROWTH INTO LARGER THUNDERSTORM CLUSTERS. THE
MORE PROBABLE TRACK FOR ANY RESULTANT MCS WOULD BE SSEWD ACROSS E
CENTRAL NM INTO W TX...W OF A LINE FROM CVS TO MAF.
...CENTRAL TX EWD ALONG THE GULF COAST TO THE SE ATLANTIC COAST...
A COMPLEX SITUATION PERSISTS OVER THIS AREA WITH THE MULTIPLE MCV/S
AND RESIDUAL BOUNDARIES FROM PREVIOUS CONVECTION...AS WELL AS
DIFFUSE FRONTAL SEGMENTS ALL POTENTIALLY SERVING AS FOCI FOR
THUNDERSTORM DEVELOPMENT. THE MOST PRONOUNCED MCV IS MOVING ESEWD
OVER NRN/CENTRAL TX TOWARD E TX AND WRN LA THIS AFTERNOON. THE
LOW-LEVEL FLOW IS WEAK AND DISORGANIZED IN ADVANCE OF THIS
WAVE...AND BOUNDARY LAYER MOISTURE/INSTABILITY HAS BEEN REDUCED SOME
BY PRIOR CONVECTIVE CLUSTERS. THERE WILL BE SOME POTENTIAL FOR
ADDITIONAL STORM DEVELOPMENT THIS AFTERNOON ALONG A WEAK BOUNDARY
CLOSE TO I-10 IN S CENTRAL TX...AND IN ADVANCE OF THE ESEWD MOVING
MCV. MODERATE INSTABILITY AND 30-45 KT MID LEVEL FLOW COULD SUPPORT
A FEW ORGANIZED MULTICELL CLUSTERS...AND PERHAPS ISOLATED STORMS
WITH SUPERCELL STRUCTURES. LARGE HAIL AND DAMAGING WINDS WILL BE
THE MAIN THREATS.
THE REGIME IS NOT SUBSTANTIALLY DIFFERENT TO THE E ACROSS SRN LA AND
S GA. ONE REMNANT MCV APPEARS TO BE MOVING OVER SW LA...AND A MORE
DIFFUSE WAVE /REMNANTS OF TX/LA MCS YESTERDAY AFTN/ IS MOVING EWD
OVER S GA. THERE ARE AREAS OF SOMEWHAT ENHANCED
MOISTURE/INSTABILITY AND MID LEVEL FLOW OVER BOTH SE LA AND SE GA IN
ASSOCIATION WITH THESE WAVES...WHERE SMALL THUNDERSTORM CLUSTERS
HAVE ALREADY DEVELOPED. THERE WILL BE SOME POTENTIAL FOR THIS
CONVECTION TO INTENSIFY AND PRODUCE DAMAGING WINDS AND SOME
HAIL...THOUGH THE SE GA CONVECTION WILL PROGRESS OFFSHORE BY EARLY
AFTERNOON.
...SD/NEB THIS AFTERNOON...
A MID LEVEL SHORTWAVE TROUGH IS PIVOTING SWD FROM THE DAKOTAS TOWARD
NEB...ON THE WRN/NWRN PERIPHERY OF THE GREAT LAKES CLOSED LOW. THIS
MID LEVEL WAVE IS ACCOMPANIED BY A SURFACE FRONTAL SEGMENT THAT IS
MOVING SWD FROM SD TOWARD NEB. INSTABILITY ALONG AND S OF THE
SURFACE BOUNDARY WILL BE RATHER MODEST /MLCAPE VALUES AOB 500 J/KG/
WITH BOUNDARY LAYER DEWPOINTS IN THE MID-UPPER 50S AND AFTERNOON
TEMPERATURES IN THE LOW-MID 70S. STILL RELATIVELY COOL TEMPERATURE
PROFILES AND LIFT ASSOCIATED WITH THE MID LEVEL WAVE AND SURFACE
BOUNDARY SHOULD SUPPORT SCATTERED THUNDERSTORM DEVELOPMENT THIS
AFTERNOON FROM SRN SD INTO NRN NEB. DESPITE NWLY LOW-LEVEL
WINDS...DEEP LAYER VERTICAL SHEAR WILL BE MARGINALLY FAVORABLE FOR
SUPERCELL TYPE STORMS. OVERALL...THE WEAK INSTABILITY WILL TEND TO
LIMIT THE SEVERE THREAT...BUT ISOLATED/MARGINALLY SEVERE HAIL AND
STRONG OUTFLOW GUSTS WILL STILL BE POSSIBLE THIS AFTERNOON/EVENING.
...EXTREME NE ORE/ERN WA/ID PANHANDLE THIS AFTERNOON...
A LEAD SHORTWAVE TROUGH IS LIFTING NNEWD OVER WRN ORE AS OF LATE
MORNING...AND THIS WAVE WILL CONTINUE OVER WRN/CENTRAL WA THIS
AFTERNOON. DOWNSTREAM FROM THIS TROUGH...A RATHER THICK BAND OF
MID-HIGH CLOUDS WILL TEMPER DAYTIME HEATING ALONG MUCH OF THE
BAROCLINIC ZONE ACROSS THE ERN ORE/WA. STRONGER SURFACE HEATING
WILL OCCUR ON THE ERN FRINGE OF THE CLOUD BAND...THOUGH 12Z
SOUNDINGS SUGGEST SURFACE TEMPERATURES MUST WARM INTO THE UPPER 80S
TO MINIMIZE CONVECTIVE INHIBITION. WILL MAINTAIN LOW PROBABILITIES
OF DAMAGING WINDS/HAIL GIVEN THE POSSIBILITY OF STORM DEVELOPMENT IN
THE ENVIRONMENT WITH MODEST INSTABILITY AND A DEEP SURFACE MIXED
LAYER.
...GREAT LAKES/OH VALLEY TODAY...
THE COLD CORE LOW CONTINUES TO DRIFT EWD OVER LAKE MI...WITH A
TRAILING WAVE AXIS MOVING EWD OVER THE LOWER OH VALLEY IN
CONJUNCTION WITH A DIFFUSE COLD FRONT. MID LEVEL LAPSE RATES ARE
LESS THAN 6 C/KM TO THE S OF THE MID LEVEL COLD POOL OVER WI/MI.
STILL...SURFACE HEATING WILL RESULT IN STEEP LOW-LEVEL LAPSE
RATES...AND A BELT OF STRONGER MID LEVEL FLOW S OF THE MID LEVEL LOW
COULD SUPPORT A FEW STORMS WITH GUSTY WINDS. IN CLOSER PROXIMITY TO
THE VERTICALLY STACKED LOW OVER LOWER MI...A FEW RELATIVELY
SHORT-LIVED STORMS WITH HAIL AND GUSTY DOWNBURST WINDS WILL BE
POSSIBLE THIS AFTERNOON GIVEN MID LEVEL LAPSE RATES CLOSE TO 7 C/KM
AND WEAK VERTICAL SHEAR.
..THOMPSON/GRAMS.. 06/04/2007
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