SWODY1
SPC AC 051628
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1128 AM CDT SAT JUN 05 2010
VALID 051630Z - 061200Z
...THERE IS A MDT RISK OF SVR TSTMS THIS AFTN AND TONIGHT ACROSS
PARTS OF THE MID MS VALLEY EWD THRU THE SOUTHERN GREAT LAKE/UPR OHIO
VALLEY....
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS OF THE ERN CNTRL
PLAINS EASTWARD THROUGH MUCH OF THE NORTHEASTERN STATES...
...MID MS VLY THRU THE SRN GREAT LAKES STATES INTO UPR OH VLY...
FAIRLY EXTENSIVE LINGERING CONVECTIVE CLOUD COVER AND PRECIPITATION
ACROSS MUCH OF THE REGION IS CONTRIBUTING TO INCREASING UNCERTAINTY
CONCERNING CONVECTIVE POTENTIAL AND PLACEMENT OF HIGHEST SEVERE
PROBABILITIES FOR THE REMAINDER OF THIS FORECAST PERIOD.
HOWEVER...LATEST OBSERVATIONAL DATA AND MODEL GUIDANCE CONTINUES TO
INDICATE FAVORABLE CONDITIONS FOR THE DEVELOPMENT OF ONE OR MORE
MESOSCALE CONVECTIVE SYSTEMS...AND POTENTIAL EXISTS FOR THE
EVOLUTION OF A LONG DURATION DAMAGING WIND/ DERECHO TYPE EVENT.
PRECIPITABLE WATER CONTENT REMAINS HIGH /1.75-2 INCHES/ IN A
WEST-EAST CORRIDOR ALONG THE SOUTHERN FRINGE OF SEASONABLY STRONG
/40-50+ KT AT 500 MB/ WESTERLIES. LOWER/MID TROPOSPHERIC LAPSE
RATES APPEAR TO HAVE STABILIZED SOME OVER THE PAST 24 HOURS... BUT
EASTWARD ADVECTION OF ELEVATED MIXED LAYER AIR IS ONGOING. THIS
PROBABLY WILL SUPPRESS CONVECTIVE DEVELOPMENT THROUGH MUCH OF THE
LOWER OHIO VALLEY...NEAR AND SOUTH OF THE RIVER...AND ACROSS THE
MIDDLE MISSISSIPPI VALLEY THROUGH MUCH OF THE DAY. HOWEVER...IT
APPEARS POSSIBLE THAT A REMNANT MESOSCALE CONVECTIVE VORTEX COULD
SUPPORT THE EVOLUTION OF ANOTHER STORM CLUSTER LATER THIS AFTERNOON
FROM PORTIONS OF INDIANA/OHIO INTO THE NORTH CENTRAL APPALACHIANS.
THEREAFTER...AS A SIGNIFICANT SHORT WAVE IMPULSE DIGS EAST
SOUTHEASTWARD...FROM THE CREST OF BROADER SCALE RIDGING OVER THE
NORTHERN ROCKIES THROUGH THE BASE OF BROADER SCALE TROUGHING TO THE
SOUTH OF THE EASTERN CANADIAN LOW...DEEP LAYER FLOW FIELDS/ SHEAR
AND FORCING FOR UPWARD VERTICAL MOTION ARE EXPECTED TO STRENGTHEN
ALONG THE FRONT OVER THE SOUTHERN GREAT LAKES REGION. IF BREAKS IN
CLOUD COVER ALLOW SUBSTANTIVE DESTABILIZATION... SEVERE STORM
DEVELOPMENT IS LIKELY...WITH SUPERCELLS EVOLVING INTO A MESOSCALE
CONVECTIVE SYSTEM ACROSS PARTS OF NORTHERN ILLINOIS INTO NORTHERN
INDIANA LATE THIS AFTERNOON AND EVENING. MODELS INDICATE THAT A
WESTERLY 850 MB JET WILL INTENSIFY IN EXCESS OF 50 KTS ASSOCIATED
WITH A DEEPENING SURFACE LOW THROUGH THE LATE EVENING INTO THE
OVERNIGHT HOURS...EASTWARD ACROSS THE REMAINDER OF THE SOUTHERN
GREAT LAKES REGION INTO THE UPPER OHIO VALLEY. THIS MAY SUPPORT A
CONTINUING/INCREASING RISK FOR STRONG DAMAGING WINDS.
FURTHER INTENSE CONVECTIVE DEVELOPMENT IS POSSIBLE UPSTREAM ALONG
THE EDGE OF THE STRONGER CAPPING CENTRAL PLAINS ELEVATED MIXED LAYER
AIR...WHICH IS PROGGED TO GRADUALLY BECOME SUPPRESSED SOUTHEASTWARD
THROUGH THE LOWER MISSOURI/MID MISSISSIPPI VALLEY TONIGHT.
...NERN STATES THIS AFTN/EVE...
STORMS ARE EXITING THE NEW ENGLAND CST IN TIME FOR AT LEAST SOME
DAYTIME HEATING. GREATER LOW LVL DESTABILIZATION WILL OCCUR FARTHER
W...OVER NY/PA. LOW-LVL MOISTURE AND RELATIVELY STEEP MID LVL LAPSE
RATES ASSOCIATED WITH WLY FLOW ALOFT WILL YIELD POCKETS OF 1500-2000
J/KG SBCAPE. AS THE GRT LKS IMPULSE CONTINUES EWD...A WEAK FRONTAL
SURGE SHOULD EVOLVE OVER WRN NEW ENGLAND...ERN NY...AND NRN PA.
SCTD TSTMS SHOULD FORM ALONG THE FRONT THIS AFTN. INSTABILITY AND
40+ KT DEEP WLY SHEAR COULD SUPPORT A FEW SUSTAINED STORMS/BRIEF
SUPERCELLS WITH SVR HAIL AND ISOLD TORNADOES. THE STORMS SHOULD
MOVE TOWARD THE CST BY EVE...WITH A CONTINUED RISK FOR MAINLY DMGG
WIND.
...MID ATLANTIC THIS AFTN...
ISOLD TO WIDELY SCTD DIURNALLY-ENHANCED TSTMS EXPECTED TO FORM OVER
THE HIGHER TERRAIN AND ALONG LEE TROUGH FROM SRN PA SWD INTO
MD/WV/VA. REGION WILL REMAIN ALONG SRN EDGE OF MODERATE TO
STRONG...DEEP UNIDIRECTIONAL WLY FLOW. COUPLED WITH FAIRLY STEEP
LOW TO MID LVL LAPSE RATES...SETUP COULD SUPPORT MULTICELLS/BANDS
WITH DMGG WIND/HAIL.
...ERN CO THIS AFTN/EVE...
ISOLD TSTMS SHOULD FORM OVER THE HIGHER TERRAIN LATER TODAY/ TONIGHT
AS LOW LVL MOISTURE INCREASES IN ENELY UPSLOPE FLOW IN WAKE OF COLD
FRONT ATTENDANT TO MT IMPULSE. AN ISOLD HIGH-BASED SUPERCELL WITH
LARGE HAIL AND/OR A LANDSPOUT WILL BE POSSIBLE NEAR THE PALMER
DIVIDE.
...NRN PLAINS THIS AFTN/EARLY EVE...
A FEW STRONG/ISOLD SVR TSTMS MAY FORM THIS AFTN/EVE OVER ND...NE
SD...AND NW MN AS MID-LVL COLD POCKET WITH AMPLIFYING UPR TROUGH
OVERSPREADS AXIS OF MODEST SFC MOISTURE EXTENDING NW FROM ERN
NEB/IA. THE STORMS COULD YIELD MARGINALLY SVR HAIL BEFORE
DIMINISHING AFTER SUNSET.
...FL THIS AFTN...
TSTMS WILL ONCE AGAIN BE NUMEROUS ALONG SEA BREEZE BOUNDARIES OVER
MUCH OF FL THIS AFTN...ESPECIALLY OVER THE INTERIOR AND E CST.
FORECAST SOUNDINGS SHOW SOME DRYING AT MID-LVLS RELATIVE TO
FRI...WITH PW REMAINING HIGH. THIS SETUP MAY YIELD ISOLD DMGG WIND
GUSTS.
...CNTRL GULF CST THIS AFTN...
SIMILAR TO YESTERDAY...A FEW STRONG STORMS WITH LOCALLY DMGG GUSTS
MAY OCCUR THIS AFTN IN MODERATE SWLY FLOW ON ERN SIDE OF GULF UPR
LOW.
..KERR/CORFIDI/IMY.. 06/05/2010
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