SWODY2
SPC AC 231732
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1232 PM CDT WED JUN 23 2010
VALID 241200Z - 251200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PORTIONS OF THE CENTRAL
APPALACHIANS TO NEW ENGLAND...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS ERN CO AND NERN NM...
...SYNOPSIS...
STRONGEST FLOW ALOFT WILL BE MAINTAINED FROM W-E ALONG THE NRN
EXTENT OF THE CONUS THROUGH THURSDAY. MODELS ARE IN AGREEMENT
SHOWING A PROGRESSIVE SHORTWAVE TROUGH WILL TRACK FROM THE LOWER
GREAT LAKES/MIDWEST REGION EWD THROUGH THE NERN STATES DURING THE
DAY THURSDAY...AND MOVE OFF THE NRN ATLANTIC COAST THURSDAY EVENING.
MEANWHILE...A CYCLONIC FLOW REGIME ALONG SRN EXTENT OF A DEEP
VORTEX CENTERED OVER HUDSON BAY/NRN QUEBEC WILL EXTEND FROM THE NRN
PLAINS TO THE MID ATLANTIC STATES. COLD FRONT ATTENDANT TO THE NEW
TROUGH WILL MOVE EWD THROUGH THE NERN AND MID ATLANTIC STATES DURING
DAY 2 AND SHOULD MOVE OFFSHORE THURSDAY EVENING. THE TRAILING
PORTION OF THIS BOUNDARY WILL MOVE SWD INTO THE TN VALLEY...MID
SOUTH AND ALONG THE RED RIVER VALLEY.
THE NEXT PACIFIC TROUGH IS EXPECTED TO MOVE FARTHER INLAND DURING
DAY 2. A MORE PROMINENT SHORTWAVE TROUGH...CURRENTLY LOCATED OFF
THE BRITISH COLUMBIA COAST...IS EXPECTED TO MOVE EWD ACROSS THE NRN
ROCKIES TO NRN HIGH PLAINS. THIS WILL RESULT IN AN UPPER RIDGE
SHIFTING EWD INTO THE NRN/CENTRAL PLAINS. A LEAD IMPULSE EXPECTED
TO BE TOPPING THE RIDGE OVER SRN SASKATCHEWAN AT 12Z THURSDAY IS
PROGGED TO TRACK SEWD WITHIN NWLY FLOW ALOFT ACROSS ND TO THE UPPER
GREAT LAKES REGION THURSDAY AFTERNOON.
...UPPER OH VALLEY/MID ATLANTIC STATES INTO NEW ENGLAND...
AT 12Z THURSDAY...TSTMS ARE EXPECTED TO BE ONGOING ALONG A COLD
FRONT FROM PARTS OF NRN NEW ENGLAND SWWD THROUGH WRN NY TO OH.
SURFACE HEATING WITHIN A MOISTENING PRE-FRONTAL AIR MASS IS EXPECTED
TO RESULT IN MODERATE INSTABILITY WITH MLCAPE 1500-2500 J/KG FROM
NEW ENGLAND SWWD INTO THE CENTRAL APPALACHIANS. STRONG FORCING FOR
ASCENT SPREADING EWD ACROSS THIS REGION WITH THE EWD MOVING TROUGH
AND FRONTAL CONVERGENCE WILL SUPPORT TSTM DEVELOPMENT THURSDAY
MORNING INTO THE AFTERNOON/EARLY EVENING. GIVEN DEGREE OF
INSTABILITY AND STRONG DEEP LAYER WLY WIND FIELDS ACCOMPANYING THE
TROUGH /60-65 KT AT 500 MB AND 50 KT AT 700 MB/...GREATEST SEVERE
WEATHER THREAT IS EXPECTED TO BE DAMAGING WINDS. MODELS SUGGEST THE
FAVORABLE ENVIRONMENT FOR SEVERE STORMS SHOULD EXTEND FARTHER SWWD
INTO PA/NRN MD/NJ THAN INDICATED BY INITIAL DAY 2 OUTLOOK.
THUS...THE SLIGHT RISK AREA HAS BEEN EXTENDED SWWD. HIGHEST
POTENTIAL FOR DAMAGING WINDS SHOULD EXTEND FROM PARTS OF PA/SRN
NY/NJ INTO SRN NEW ENGLAND WHERE INSTABILITY WILL BE GREATEST AND
STRONGEST WLY WINDS WILL BE FOCUSED. EFFECTIVE BULK SHEAR ACROSS
THIS SAME REGION WILL BE SUFFICIENT FOR SUPERCELLS...SO HAIL AND AN
ISOLATED TORNADO THREAT CANNOT BE RULED OUT.
...ERN CO/NERN NM...
MODELS ARE IN GENERAL AGREEMENT THAT STORMS SHOULD DEVELOP OVER THE
HIGHER TERRAIN/CO FRONT RANGE SWD INTO NERN NM THURSDAY
AFTERNOON...WITH ACTIVITY MOVING EWD ONTO THE ADJACENT HIGH PLAINS
DURING THE LATE AFTERNOON/EARLY EVENING. MODERATE INSTABILITY AND
EFFECTIVE BULK SHEAR 30-40 KT WILL BE SUPPORTIVE OF SUPERCELLS WITH
PRIMARY THREATS FOR HAIL AND STRONG WIND GUSTS. THIS THREAT AREA
SHOULD BE PRIMARILY DIURNAL WITH ACTIVITY TENDING TO WEAKEN AFTER
DARK.
...TN VALLEY TO MID SOUTH...
MODELS REMAIN CONSISTENT SHOWING SHEAR PROFILES WEAKENING
CONSIDERABLY INTO THE TN VALLEY TO MID SOUTH ALONG TRAILING FRONT.
DESPITE THIS LIMITING FACTOR FOR A MORE ORGANIZED SEVERE WEATHER
THREAT...STRONG HEATING AND RICH BOUNDARY LAYER MOISTURE WILL RESULT
IN A MODERATELY TO VERY STRONGLY UNSTABLE AIR MASS. THIS COMBINED
WITH FRONTAL CONVERGENCE WILL BE ADEQUATE FOR ISOLATED STRONG TO
SEVERE STORMS...PRIMARILY DURING THE LATE AFTERNOON HOURS. PRIMARY
SEVERE THREAT SHOULD BE STRONG WIND GUSTS OWING IN PART TO EXPECTED
STEEP LOW LEVEL LAPSE RATES.
...NRN HIGH PLAINS EWD TO DAKOTAS/NRN MN...
A BAROCLINIC ZONE IS EXPECTED TO DEVELOP FROM NRN WI NWWD THROUGH
NRN MN...NRN ND TO SRN SASKATCHEWAN AND CENTRAL ALBERTA ON THURSDAY.
MODELS SUGGEST CONVECTION WILL DEVELOP ALONG THE EXTENT OF THIS
BOUNDARY AS A COUPLE OF IMPULSES IN NWLY FLOW TRACK ACROSS THE BOTH
THE CANADIAN AND U.S. PORTIONS OF THE FRONT. STRONGEST INSTABILITY
SHOULD REMAIN IN CANADA...THOUGH WEAK INSTABILITY AND STRONG NWLY
DEEP LAYER SHEAR VECTORS ACROSS PARTS OF NRN ND INTO NRN MN SUGGEST
AT LEAST A LOW PROBABILITY FOR SEVERE STORMS.
FARTHER WEST...HEIGHT FALLS ARE NOT EXPECTED TO OVERSPREAD WRN MT
UNTIL LATE IN THE PERIOD RESULTING IN MUCH OF THE NRN PLAINS TO
EXPERIENCE WEAK/NEUTRAL UVV WITHIN A SLOW RECOVERING WARM SECTOR.
THE LARGE SCALE PATTERN FAVORS A DEVELOPING LEE TROUGH WHICH SHOULD
BECOME ESTABLISHED LATE FROM CNTRL MT...SEWD ACROSS ERN WY INTO ERN
CO. LATEST MODELS SUGGEST A TSTMS MAY DEVELOP NEAR/EAST OF THE DRY
LINE/LEE TROUGH DUE PRIMARILY TO STRONG HEATING. OTHER ISOLATED
STORMS MAY ALSO DEVELOP WITHIN STRENGTHENING WARM ADVECTION ZONE
LATE ACROSS THE WRN DAKOTAS. MEAGER FORCING AND MARGINAL
INSTABILITY DO NOT APPEAR TO WARRANT MORE THAN LOW PROBABILITIES FOR
SEVERE DESPITE THE STEEP LAPSE RATE ENVIRONMENT.
..PETERS.. 06/23/2010
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