Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
Columbus, OH...Oklahoma City, OK...Cincinnati, OH...Amarillo, TX...Springfield, MA...
SPC AC 121307
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0807 AM CDT FRI JUN 12 2015
VALID 121300Z - 131200Z
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS LOWER GREAT LAKES
REGION TO WRN NEW ENGLAND...
...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS SRN PLAINS...
...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING GREAT LAKES/NEW
ENGLAND SLGT RISK...
...THERE IS A MRGL RISK OF SVR TSTMS SURROUNDING SRN PLAINS SLGT
RISK AND INTO SRN CO/NERN NM...
...THERE IS A MRGL RISK OF SVR TSTMS NWRN ND AND EXTREME NERN MT...
...SUMMARY...
AREAS OF ORGANIZED SEVERE THUNDERSTORMS ARE POSSIBLE TODAY FROM
PARTS OF ILLINOIS TO WESTERN NEW ENGLAND...AND OVER SOME OF WESTERN
OKLAHOMA AND WEST AND NORTHWEST TEXAS. ISOLATED SEVERE STORMS MAY
OCCUR THIS AFTERNOON INTO EARLY EVENING OVER WESTERN NORTH DAKOTA
AND NEARBY PARTS OF EXTREME EASTERN MONTANA.
...SYNOPSIS...
MID/UPPER-LEVEL PATTERN WILL BE CHARACTERIZED BY SPLIT FLOW...WITH
NRN-STREAM BELT REMAINING OVER NWRN CONUS AND S-CENTRAL/SERN CANADA.
WEAK SHORTWAVE TROUGH NOW LOCATED OVER PORTIONS WI/IL IS EXPECTED
TO TURN EWD ACROSS LOWER MI AND SWRN ONT...PHASING/MERGING WITH
ANOTHER SHORTWAVE TROUGH INITIALLY LOCATED OVER NRN ONT.
RESULTANT/COMBINED PERTURBATION SHOULD CROSS LOWER GREAT LAKES AND
REACH NRN NEW ENGLAND AROUND 06Z. MEANWHILE...MID/UPPER-LEVEL
HEIGHT FALLS ARE FCST OVER NRN ROCKIES AND NRN HIGH PLAINS THROUGH
PERIOD...AS BROAD/COMPLEX CYCLONE SLOWLY EVOLVES AND SHIFTS EWD
ACROSS MUCH OF AB/SK.
MESSY AREA OF MID/UPPER-LEVEL TROUGHING...WITH SEVERAL EMBEDDED
SHORTWAVE PERTURBATIONS AND RELATED VORTICITY MAXIMA...IS EVIDENT IN
MOISTURE-CHANNEL IMAGERY FROM CENTRAL/SRN ROCKIES WSWWD ACROSS SRN
PORTIONS NV/CA. LEADING PERTURBATION OVER NRN NM/SRN CO IS EXPECTED
TO MOVE EWD TO WRN KS...TX PANHANDLE...AND ERN NM BY 00Z. THIS
FEATURE SHOULD MOVE GENERALLY EWD TO ERN KS...WRN OK AND PERHAPS NW
TX BY END OF PERIOD...ITS SRN EXTENT PERHAPS INFLUENCED BY
CONVECTIVE ENHANCEMENT.
AT SFC...11Z ANALYSIS SHOWED PRIMARY FRONTAL-WAVE LOW OVER ERN IA.
WAVY...QUASISTATIONARY AND OCCASIONALLY CONVECTIVELY MODULATED FRONT
EXTENDED EWD ACROSS SWRN LOWER MI TO NERN PA AND OFFSHORE NYC AREA.
COLD FRONT WAS DRAWN FROM ERN IA SWWD ACROSS NWRN MO TO E-CENTRAL
KS. FARTHER SW ACROSS SRN HIGH PLAINS...COLD FRONT HAS BEEN
OBSCURED BY EXTENSIVE CONVECTIVE COLD POOL THAT COVERS MUCH OF SRN
KS...N-CENTRAL TO WRN OK...TX PANHANDLE AND NERN NM. MAIN SFC LOW
IS FCST TO MOVE GENERALLY EWD WITHIN SFC FRONTAL ZONE TO NEW ENGLAND
BY 12Z...WHILE TRAILING PORTION OF FRONT BECOMES QUASISTATIONARY
AFTER LOW PASSAGE ACROSS OH...INDIANA...IL AND NRN MO. SEPARATE
COLD FRONT...PRECEDING NRN-STREAM CYCLONE OVER WRN CANADA...WILL
SHIFT EWD ACROSS CENTRAL/ERN MT TO WRN ND.
...GREAT LAKES STATES...WRN NEW ENGLAND...
SCATTERED TSTMS ARE FCST TO DEVELOP THIS AFTN INVOF FRONTAL
ZONE...AHEAD OF SFC LOW AND ALONG/AHEAD OF OUTFLOW BOUNDARY FROM
ANTECEDENT/ONGOING CONVECTION OVER IL. SEVERAL AREAS OF RELATIVELY
MAXIMIZED SVR POTENTIAL ARE POSSIBLE...HOWEVER THESE WILL DEPEND ON
MESOSCALE PROCESSES YET TO DEVELOP. DAMAGING GUSTS AND LARGE HAIL
ARE PRIMARY CONCERNS...BEFORE ACTIVITY WEAKENS LATE THIS EVENING.
...SRN PLAINS...
MAIN FEATURES OF INTEREST FOR THIS AREA WILL BE OUTFLOW BOUNDARY
DELINEATING SRN RIM OF AFOREMENTIONED COLD POOL...AND DRYLINE THAT
SHOULD MIX EWD OFF HIGHER TERRAIN OF SRN NM AND FAR W TX. OUTFLOW
BOUNDARY HAS PASSED LBB AND CVS...BUT IS DECELERATING AND SHALLOW
OVER THIS AREA BASED ON RADAR TRENDS...LBB VWP AND SFC OBS. THIS
BOUNDARY SHOULD RETREAT NWD SOMEWHAT THROUGH AFTN...PERHAPS AS FAR N
AS BETWEEN PVW-AMA BUT MORE PROBABLY INTO PVW-LBB AREA AND POINTS E
AND W FROM THERE. BY 21Z...DRYLINE SHOULD CROSS PARTS OF N-S
SEGMENT OF TX/NM BORDER...S OF OUTFLOW BOUNDARY...WITH INTERSECTION
OVER S PLAINS REGION. THESE BOUNDARIES WILL ACT AS PRIMARY FOCI FOR
AFTN CONVECTIVE INITIATION...SOME OF WHICH MAY ASSUME SUPERCELLULAR
CHARACTERISTICS GIVEN
1. SMALL BELT OF ENHANCED MIDLEVEL FLOW AND DEEP SHEAR S/SE OF
MID/UPPER-LEVEL PERTURBATION AND
2. ENHANCED LOW-LEVEL VORTICITY/LIFT...BACKED FLOW AND RELATED SRH
MAX ALL LIKELY INVOF OUTFLOW BOUNDARY.
LARGE HAIL AND DAMAGING GUSTS ARE EXPECTED FROM SUPERCELLS...AND A
TORNADO OR TWO MAY OCCUR ESPECIALLY WITH ANY SUSTAINED AND
RELATIVELY DISCRETE STORM THAT MAY LATCH ONTO REMNANT OUTFLOW
BOUNDARY FOR AN HOUR OR TWO OF ITS MATURE PHASE. UPSCALE
EVOLUTION/GROWTH OF CONVECTION IS EXPECTED LATE AFTN AND EVENING
ALONG AND S OF BOUNDARY WITH ATTENDANT SVR-GUST/HAIL RISK.
RESULTANT QLCS SHOULD WEAKEN LATE EVENING OR OVERNIGHT IN SRN OK AND
N-CENTRAL/W-CENTRAL TX.
...NRN HIGH PLAINS...
AFOREMENTIONED HEIGHT FALLS ALOFT WILL START TO INFLUENCE THIS AREA
AROUND OR SHORTLY BEFORE SFC FROPA...AS WILL RELATED INCREASE IN
GRADIENT FLOW ALOFT AND IN DEEP SHEAR. HOWEVER...WITH STRONGEST
LARGE-SCALE ASCENT AND FRONTOGENETIC FORCING EACH REMAINING N OF
INTERNATIONAL BORDER...CONVERGENCE WILL BE LIMITED INVOF SFC COLD
FRONT. GIVEN THOSE FACTORS...AND LACK OF SUBSTANTIAL LOW-LEVEL
MOISTURE...MRGL SVR PROBABILITIES HAVE BEEN SHIFTED CLOSER TO
BORDER...AND SVR THREAT ON CONUS SIDE APPEARS VERY CONDITIONAL ATTM.
ANY SUSTAINED TSTMS THAT FORM WILL OFFER THREAT OF DAMAGING GUSTS
AND LARGE HAIL MAINLY LATE AFTN INTO EARLY EVENING.
..EDWARDS/COHEN.. 06/12/2015
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
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