Tuesday, June 11, 2013

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 111632
SWODY1
SPC AC 111630

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1130 AM CDT TUE JUN 11 2013

VALID 111630Z - 121200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF THE NRN PLNS/MID
MO VLY...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE N CNTRL HIGH PLNS E
INTO THE MID MS VLY...

...SYNOPSIS...
ELONGATED SUBTROPICAL RIDGE NOW EXTENDING FROM THE SRN RCKYS INTO
THE CNTRL/SRN PLNS WILL EXPAND EWD THIS PERIOD IN WAKE OF UPR
IMPULSE THAT CROSSED THE TN VLY YESTERDAY. AT THE SAME TIME...POTENT
SHORTWAVE TROUGH NOW OVER UT WILL CONTINUE ENE INTO THE NRN/CNTRL
HIGH PLNS THIS EVE...BEFORE TURNING E AS IT CRESTS THE RIDGE TO
REACH SD/NEB EARLY WED.

GIVEN THE ABOVE PATTERN...EXPECT STOUT EML...WELL-DEPICTED IN THE
MORNING RAOB DATA...TO REMAIN IN PLACE INTO TNGT FROM THE N CNTRL HI
PLNS EWD INTO MID-MS/LWR OH VLYS.

AT THE SFC...CNTRL HIGH PLNS LEE LOW SHOULD REMAIN NEARLY STNRY
TODAY BEFORE ADVANCING E ACROSS SRN NEB TNGT AHEAD OF UPR TROUGH. A
CORRIDOR OF FAIRLY RICH BOUNDARY LAYER MOISTURE AND LOW-LVL ELY FLOW
WILL PERSIST N OF A W-E FRONT EXTENDING E FROM THE LOW INTO MID-MS
VLY.

COMBINATION OF LOW-LVL MOISTURE INFLOW...SFC HEATING...AND
APPROACHING UPR TROUGH LIKELY WILL LEAD TO STRONG TSTM DEVELOPMENT
BY MID TO LATE AFTN OVER PARTS OF ERN WY AND WRN SD. THIS ACTIVITY
LIKELY WILL GROW UPSCALE INTO A SVR MCS THAT MOVES GENERALLY E ALONG
THE NRN FRINGE OF THE EML CAP AND ALONG LOW-LVL MOIST AXIS THROUGH
EARLY WED. IN THE MEANTIME...SCTD AREAS OF STRONG TO LOCALLY SVR
DIURNAL STORMS MAY OCCUR TODAY OVER PARTS OF THE EAST AND
INTERMOUNTAIN WEST. IN ADDITION...WDLY SCTD ELEVATED STORMS WITH
HAIL MAY OCCUR EARLY WED IN STRENGTHENING WAA ZONE ON NE FRINGE OF
THE EML OVER THE OH VLY.

...N CNTRL HIGH PLNS TO MID MS VLY TODAY THROUGH EARLY WED...
LOW-LVL MOISTURE WILL FURTHER INCREASE ACROSS SD...NRN NEB...ERN
WY...AND SE MT TODAY IN ELY UPSLOPE FLOW N OF STALLED FRONT/LEE LOW.
COUPLED WITH STRONG SFC HEATING AND INCREASING UPR LVL
DIVERGENCE/DCVA WITH APPROACH OF UT UPR VORT...SETUP WILL BECOME
FAVORABLE FOR STRONG TSTM DEVELOPMENT NEAR THE HIGHER TERRAIN AND
ALONG LEE TROUGH AND BY MID TO LATE AFTN. COMBINATION OF STRONG
INSTABILITY /MUCAPE TO 2500 J PER KG/ AND 40 KT WSWLY DEEP SHEAR
LIKELY WILL YIELD SCTD SUPERCELLS CAPABLE OF VERY LARGE
HAIL...LOCALLY DMGG WIND...AND TORNADOES...ESPECIALLY IN SW SD...NE
WY...AND NW NEB.

GIVEN VERY DEEP/STRONG EML...PRESENCE OF 40-50 KT UNIDIRECTIONAL WLY
MID/UPR-LVL FLOW...AND MOIST/ELY LOW-LVL FLOW...SETUP APPEARS
FAVORABLE FOR UPSCALE DEVELOPMENT INTO A SVR FORWARD-PROPAGATING/
POSSIBLE DERECHO-PRODUCING CONVECTIVE SYSTEM. SUCH A SYSTEM COULD
EXTEND A RISK FOR SVR WIND...HAIL..AND ISOLD TORNADOES E INTO NE
NEB/NW A/SE SD AREA BY 12Z WED. FARTHER E...SMALLER...SOMEWHAT
ELEVATED CONVECTIVE SYSTEMS/STORMS MAY FORM DURING THE OVERNIGHT
OVER PARTS OF IL/IND/OH IN ZONE OF STRENGTHENING WAA/MOISTURE
TRANSPORT ON NERN FRINGE OF EML.

...SRN NEW ENGLAND/LWR HUDSON VLY/NJ THIS AFTN...
SFC HEATING IN NARROW CORRIDOR OF CLEARING ON SW SIDE OF CLOUD
SHIELD ASSOCIATED WITH CAPE COD AREA SFC LOW MAY SUPPORT DEVELOPMENT
OF SCTD STRONG AFTN/EVE STORMS WITH GUSTY WINDS IN ASSOCIATED ZONE
OF WEAK LOW-LVL CONFLUENCE.

...PARTS OF GA/SC THIS AFTN...
WDLY SCTD STRONG STORMS ALSO MAY FORM IN ZONE OF WEAK ASCENT ON
TRAILING SW END OF UPR IMPULSE THAT CROSSED THE TN VLY YESTERDAY.
WIND AND THERMODYNAMIC ENVIRONMENT MAY SUPPORT AN INSTANCE OR TWO OF
LOCALLY DMGG WIND/MARGINALLY SVR HAIL.

..CORFIDI/SMITH.. 06/11/2013

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