SPC AC 170728
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0228 AM CDT THU JUN 17 2010
VALID 191200Z - 201200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER THE LOWER GREAT LAKES AND
MIDWEST...
...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF MT...
...SYNOPSIS...
AS THE UPPER HIGH BEGINS ITS SEASONAL SHIFT WWD THROUGH THE SRN
STATES...MOBILE UPPER TROUGH ACROSS THE GREAT LAKES WILL SHIFT
ACROSS NEW ENGLAND BY SATURDAY NIGHT. UPSTREAM...A NEW TROUGH WILL
DIG INTO THE PACIFIC NW AS MID-LEVEL SHORTWAVE SPLINTERS EJECT ENE
AROUND THE PERIPHERY OF THE RIDGE TO THE PLAINS STATES.
...LOWER GREAT LAKES TO THE MIDWEST...
BASE OF THE AFOREMENTIONED UPPER TROUGH/50 KTS OF 500 MB FLOW WILL
SKIRT ACROSS THE REGION SATURDAY AFTERNOON AMID A VERY MOIST AIR
MASS. HEATING AND ASCENT SHOULD BE SUFFICIENT FOR A FEW
THUNDERSTORMS ALONG THE ATTENDANT COLD FRONT/PRE-FRONTAL TROUGH FROM
THE LOWER GREAT LAKES SWWD INTO AT LEAST IND/IL. RELATIVELY COOL
MID-LEVELS AND MODESTLY FAST FLOW MAY YIELD A FEW SEVERE STORMS
CAPABLE OF HAIL/HIGH WINDS. MODELS ARE IN DISAGREEMENT ON THE ERN
EXTENT OF THE SEVERE THREAT...WITH THE MORE WESTERN SOLUTIONS OF THE
NAM/ECMWF PREFERRED.
...MT...
SWLY MID-LEVEL FLOW OF 40-45 KTS WILL CONTINUE ACROSS THE
INTERMOUNTAIN W AS THE PACIFIC NW UPPER LOW EDGES EWD. RELATIVELY
COOL TEMPERATURES ALOFT...HEATING ALONG THE TERRAIN AND MODEST
PRECIPITABLE WATER VALUES WILL CONTRIBUTE TO A ROUND OF
STRONG-SEVERE STORMS SATURDAY AFTN/EVENING. SUPERCELLS WILL BE
POSSIBLE WITH LARGE HAIL AND HIGH WINDS THE PRIMARY THREATS.
...TN VLY/SCNTRL GULF COAST...
POTENTIAL VORTICITY TAIL/MID-LEVEL COLD POCKET /H5 TEMPS AROUND
MINUS 10C/ WILL SETTLE SWD ALONG ERN EDGE OF THE UPPER HIGH AND WILL
INVIGORATE MULTICELL STORM CLUSTERS SATURDAY AFTERNOON/EVENING.
DEEP LAYER NLY FLOW AND FAVORABLE THERMODYNAMICS COULD LEAD TO AT
LEAST A COUPLE OF DAMAGING MICROBURSTS. THREATS SHOULD DIMINISH
AFTER DARK.
...CNTRL PLAINS...
AREA WILL REMAIN ALONG NRN EDGE OF THE RETREATING UPPER HIGH WITH
AIR MASS STRONGLY HEATING. CAPPING CONCERNS LEAD TO A LOW
CONFIDENCE FORECAST...ALTHOUGH HEATING ALONE ALONG THE LEE
TROUGH/DRYLINE MAY BE SUFFICIENT FOR AT LEAST ISOLD SFC-BASED STORMS
DURING THE LATE AFTN/EVE. SUPERCELLS COULD RESULT WITH LARGE
HAIL...TRANSITIONING INTO ELEVATED STORM CLUSTERS OVER PARTS OF
NEB/IA SATURDAY NIGHT. GIVEN THE OVERALL UNCERTAINTY...A SLIGHT
RISK IS NOT WARRANTED AT THIS TIME.
..RACY.. 06/17/2010
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z
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