SPC AC 211720
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1220 PM CDT SUN JUN 21 2009
VALID 221200Z - 231200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NRN PLAINS/CORN
BELT...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS CNTRL/SRN FL...
...SYNOPSIS...
SPRAWLING UPR HIGH CENTERED OVER THE LWR MS VLY WILL RETROGRADE WWD
INTO THE SRN PLAINS AND BUILD NWD INTO THE NRN PLAINS AND UPR MS VLY
ON MONDAY. ALONG ERN PERIPHERY OF THE HIGH...CIRCULATION AROUND A
WRN ATLC BASIN CYCLONE WILL SEND SHORTWAVE TROUGHS SWD ALONG THE ERN
SEABOARD. MEANWHILE...UPR LOW TURNING NEWD INTO THE NRN ROCKIES
WILL SPREAD NEWD...GLANCING OFF NRN PARTS OF THE RIDGE...INTO SCNTRL
CANADA DURING THE DAY2 PD. AT THE SFC...A SERIES OF BACKDOOR CDFNTS
WILL SETTLE SWD ALONG THE ATLC CST...BUT PRIMARY BAROCLINIC ZONE
SHOULD EXIST FROM GA NWWD INTO THE MIDWEST. TAIL END OF THE FRONT
WILL BE REDEVELOPING NWD AS A WRMFNT...INTERSECTING WITH A WEAK
CDFNT/LEE TROUGH PROGGED TO MOVE EWD INTO THE NRN HIGH PLAINS.
...NRN PLAINS/CORN BELT...
A BAND OF ELEVATED CONVECTION WILL BE COMMONPLACE ACROSS THE UPR MS
VLY EARLY MONDAY...ALONG/N OF THE SURGING WRMFNT THAT WILL MARK THE
LEADING EDGE OF INCREASED CAPPING/HOT BOUNDARY LAYER. IN ITS
WAKE...RISING HEIGHTS AND H5/H7 TEMPS WARMING AOA MINUS 6/PLUS 12
DEG C RESPECTIVELY WILL BE HOSTILE TO SUPPORT DEEP MOIST CONVECTION
OVER SRN NEB AND SRN IA MONDAY AFTN. HOWEVER...AS THE NRN ROCKIES
UPR SYSTEM EJECTS NEWD TOWARD SCNTRL CANADA...UPR RIDGE FLATTENS AND
MID-LVL TEMPERATURES COOL 1-2 DEG C OVER ESPECIALLY THE WRN/CNTRL
DKTS...BUT PERHAPS AS FAR SE AS NRN NEB/NWRN IA BY MONDAY EVENING.
SFC DEW POINTS RANGING FROM THE MID-60S TO MID-70S F AND WEAK LARGE
SCALE FORCING FOR ASCENT MAY CONTRIBUTE TO A SFC-BASED TSTM THREAT
FROM THE WRN/CNTRL DKTS /ALONG THE LEE-TROUGH-CDFNT/ SEWD INTO NRN
NEB AND NWRN IA /INVOF WRMFNT/. SHOULD STORMS FORM...35-40 KTS OF
0-6KM SHEAR AND MAGNITUDE OF BUOYANCY WILL BE FAVORABLE FOR
SUPERCELLS WITH LARGE HAIL/HIGH WINDS. A COUPLE SMALL MCS/S MAY
EVOLVE MONDAY NIGHT...DVLPG EWD INTO WRN MN AND CNTRL/ERN IA.
ACTIVITY MAY POSE A HAIL/HIGH WIND RISKS AFT DARK...ESP ACROSS THE
CORN BELT.
...FL...
INCREASING DEEP-NORTHERLIES ARE PROGGED ACROSS FL MONDAY AFTN AS
DISTURBANCES DIG SWD ALONG WRN PERIPHERY OF THE WRN ATLANTIC UPR
LOW. LLVL MOISTURE SHOULD REMAIN HIGH WITH DEW POINTS IN THE 70S
WITH VERY UNSTABLE CONDITIONS. THOUGH RELATIVELY WARM MID-LVLS MAY
BE SOMEWHAT OF LIMITING FACTOR...ADDED LARGE SCALE LIFT INVOF THE
SEABREEZES/WEAK CDFNT SHOULD COMPENSATE AND SCTD TSTMS SHOULD DVLP
EARLY/MID-AFTN. GIVEN THE FLOW REGIME...CONVECTIVE MODE SHOULD
EVOLVE INTO SWD MOVING CLUSTERS CAPABLE OF DMGG WINDS/HAIL. AN
ISOLD TORNADO THREAT WILL BE CONDITIONAL ON STORM MODE/MOVEMENT IN
RELATION TO SEABREEZES/OUTFLOW BOUNDARIES.
..RACY.. 06/21/2009
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z
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