SPC AC 090553
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1253 AM CDT TUE JUN 09 2009
VALID 101200Z - 111200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER A LARGE PART OF THE SRN
PLNS NEWD TO THE OH VLY...
...SYNOPSIS...
A SPLIT FLOW REGIME WILL CONTINUE DURING THE MID-WEEK PD AND FEATURE
A SRN STREAM TROUGH ACROSS THE GRT BASIN/SWRN STATES AND A PROMINENT
NRN BRANCH UPR LOW ALONG THE NRN TIER OF THE COUNTRY. A LEAD
SHORTWAVE TROUGH EMANATING FROM THE FORMER FEATURE IS FCST TO MOVE
FROM THE MID-MS VLY INTO THE MIDWEST AS IT PHASES WITH THE NRN
STREAM UPR LOW. MEANWHILE...A STRONGER WAVE...CURRENTLY ROUNDING
THE BASE OF THE PAC UPR LOW...WILL QUICKLY MOVE INTO THE SRN PLNS BY
WEDNESDAY EVENING. RESULTANT BOUTS OF MODEST HEIGHT FALLS SPREADING
ENE ALONG A BAROCLINIC ZONE...RESIDING FROM THE SRN PLNS TO THE OH
VLY REGION...WILL BE IMPETUS FOR EPISODIC TSTM CLUSTERS.
...MIDWEST/MID-UPR OH VLY TO THE CNTRL APLCNS...
A CLUSTER OF TSTMS...PSBLY PRODUCING HAIL/GUSTY WINDS...WILL BE
ONGOING AT THE START OF THE PD OVER PORTIONS OF THE MID-MS
VLY/MIDWEST. CONVECTIVELY ENHANCED MID-LVL SPEED MAX ASSOCD WITH
THIS ACTIVITY IS THEN EXPECTED TO TRANSLATE TOWARD THE MID-ATLC
REGION BY WEDNESDAY NIGHT. CDFNT THAT SETTLES INTO THE OH VLY/CNTRL
APLCNS TODAY/TONIGHT WILL RETURN NWD INTO CNTRL OH/PA...WITH RAPID
RECOVERY OF LLVL MOISTURE LIKELY AHEAD OF REMNANT NOCTURNAL
CONVECTION. EXPECT THAT SFC-BASED STORMS WILL DEVELOP WEDNESDAY
AFTN OVER THE MIDWEST ALONG SRN FRINGE OF EARLY DAY ACTIVITY...AND
THEN MOVE EWD ACROSS THE CNTRL APLCNS DURING THE NIGHT. 40-50 KTS
OF WLY FLOW WILL BE FAVORABLE FOR SOME ORGANIZED
STORMS...PARTICULARLY WEST OF THE MOUNTAINS WHERE STRONGER LLVL
THETA-E AXIS WILL EXIST. DMGG WIND GUSTS AND PERHAPS A TORNADO OR
TWO WILL BE THE PRIMARY SVR RISKS.
...LWR OH VLY/OZARK PLATEAU SWWD INTO THE SRN PLNS...
MID-LVL SHORTWAVE RIDGING WILL BE SHORT-LIVED IN WAKE OF THE
DEPARTING UPR OH VLY DISTURBANCE. A COMPARATIVELY STRONGER IMPULSE
AND ASSOCD ASCENT ARE LIKELY TO ARRIVE OVER THE SRN PLNS BY
WEDNESDAY MID-AFTN AND SPREAD QUICKLY NEWD TOWARD THE OZARK
PLATEAU/LWR OH VLY DURING THE EVENING. AIR MASS ALONG/S OF THE
RETREATING FRONT WILL BECOME VERY UNSTABLE OWING TO MID-UPR 60S SFC
DEW POINTS AND STEEP LAPSE RATES. HEATING ALONE WILL PROBABLY NOT
BE SUFFICIENT FOR IGNITING STORMS GIVEN THE REBOUNDING CAP.
BUT...ADDED MOISTENING VIA LARGER SCALE ASCENT AND PERSISTENT MOIST
INFLOW/FRONTAL CONVERGENCE SHOULD AID IN GENERATING SFC-BASED STORMS
FROM SRN IL WWD ACROSS CNTRL/SRN MO AND ERN KS BY MID-AFTN.
ADDITIONAL STORMS WILL FORM SWWD ACROSS PORTIONS OF OK AND W TX NEAR
THE DRYLINE BY LATE AFTN...AND ESPECIALLY DURING THE EVENING/NIGHT.
THE ENTIRE REGION WILL RESIDE IN EFFECTIVE DEEP LAYER SHEAR
SUFFICIENT FOR SUPERCELLS...PARTICULARLY ALONG THE DRYLINE. FARTHER
TO THE N AND E...SOMEWHAT UNIDIRECTIONAL FLOW REGIME WILL FAVOR A
TRANSITION INTO BOWS/LEWPS...WHILE DISCRETE SUPERCELLS ARE LIKELY
FARTHER TO THE S. LARGE HAIL...DMGG WIND GUSTS AND PERHAPS A
TORNADO OR TWO CAN BE EXPECTED.
ACTIVITY ALONG THE E-W BAROCLINIC ZONE WILL DEVELOP INTO SVRL MCS/S
WEDNESDAY NIGHT...WITH A DMGG WIND THREAT PSBLY SPREADING THROUGHOUT
THE OH/LWR TN VLY BY 12Z THUR. MEANWHILE...PERSISTENT AND WEAK
CYCLONIC UPR FLOW AND A 25-30 KT WSWLY LLJ WILL BE FAVORABLE FOR THE
SRN PLNS STORM CLUSTERS TO EXHIBIT BACKBUILDING QUALITIES THROUGH
THE NIGHT WITH AT LEAST A LARGE HAIL THREAT.
..RACY.. 06/09/2009
CLICK TO GET WUUS02 PTSDY2 PRODUCT
NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
|
