SWODY2
SPC AC 230550
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1250 AM CDT MON JUL 23 2007
VALID 241200Z - 251200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
THE BULK OF THE NORTHEASTERN PACIFIC TROUGH APPEARS TO BE IN THE
PROCESS OF LIFTING TOWARD THE BRITISH COLUMBIA/PACIFIC NORTHWEST
COAST...MUCH AS HAS BEEN INDICATED BY THE MODELS THE PAST FEW DAYS.
THE SYSTEM IS FORECAST TO PROGRESS ACROSS THE CANADIAN ROCKIES
TODAY...BEFORE CONTINUING EAST NORTHEASTWARD TOWARD HUDSON BAY
THROUGH LATE TUESDAY NIGHT/EARLY WEDNESDAY. THIS WILL BEGIN TO
FLATTEN THE CENTRAL CANADIAN RIDGE AXIS...WHICH EXTENDS TO THE NORTH
OF AN UPPER HIGH CENTER OVER THE NORTH CENTRAL HIGH PLAINS.
AND...SOME FURTHER WEAKENING OF THE WARM CORE HIGH MAY ENSUE.
BUT...IN GENERAL...A STRONG RIDGE IS EXPECTED TO PERSIST FROM THE
FOUR CORNERS STATES THROUGH THE NORTHERN PLAINS...THROUGH THIS
FORECAST PERIOD.
FARTHER EAST...MODELS CONTINUE TO INDICATE THAT A WESTERN ATLANTIC
MID-LEVEL RIDGE WILL EXPAND WESTWARD THROUGH THE WESTERN CARIBBEAN
..FLORIDA PENINSULA...AND EASTERN GULF OF MEXICO. AND...THE WEAK
EASTERN STATES CLOSED LOW WILL REMAIN CUT-OFF FROM THE POLAR
WESTERLIES...BETWEEN THE TWO RIDGES...PERHAPS SLOWLY SHIFTING
NORTHWESTWARD THROUGH PARTS OF THE MID ATLANTIC STATES/LOWER GREAT
LAKES AND OHIO VALLEY.
..CENTRAL PLAINS...
MODELS ARE SUGGESTIVE THAT AN IMPULSE...LIKELY TO CONTRIBUTE TO
STRENGTHENING NORTHEASTERLY MID/UPPER FLOW ACROSS THE MID MISSOURI
VALLEY TODAY...WILL CONTINUE SOUTHWESTWARD AROUND THE SOUTHEASTERN
PERIPHERY OF THE UPPER RIDGE TUESDAY/TUESDAY NIGHT. THIS COULD
ENHANCE FLOW FIELDS A BIT ACROSS PARTS OF THE CENTRAL/SOUTHERN
PLAINS. BUT...IN GENERAL...WINDS/DEEP LAYER SHEAR PROBABLY WILL
REMAIN WEAK. HOWEVER...A MODERATE TO STRONGLY UNSTABLE BOUNDARY
LAYER...WITH MIXED LAYER CAPE OF 2000-3000 J/KG...AND UNSATURATED
THERMODYNAMIC PROFILES...MAY BE SUPPORTIVE OF A FEW STRONG/ISOLATED
SEVERE STORMS AS INHIBITION WEAKENS IN PEAK AFTERNOON HEATING.
LOCALIZED STRONG WIND GUSTS ARE EXPECTED TO BE THE PRIMARY SEVERE
THREAT...BUT SOME MARGINALLY SEVERE HAIL MAY BE POSSIBLE.
..SOUTHEAST STATES...
ALTHOUGH A GRADUAL WARMING ALOFT IS STILL FORECAST TO COMMENCE
TUESDAY...INHIBITION IS EXPECTED TO REMAIN WEAK ENOUGH TO ALLOW
CONSIDERABLE CONVECTIVE DEVELOPMENT ALONG A WEAK/WEAKENING SURFACE
FRONT AND SEA BREEZES ACROSS PARTS OF THE GULF COAST STATES.
CONVERGING BOUNDARIES ACROSS THE CENTRAL PENINSULA INTO NORTHERN
FLORIDA DURING THE PEAK HEATING HOURS MAY PROVIDE A FOCUS FOR THE
MOST VIGOROUS STORMS...WITHIN A THERMODYNAMIC ENVIRONMENT THAT
SHOULD STILL BE CONDUCIVE FOR LOCALIZED DOWNBURSTS...PERHAPS SOME
HAIL.
..INTERMOUNTAIN WEST INTO THE LEE OF THE MONTANA ROCKIES...
TROPICAL MOISTURE PLUME AND FORCING ASSOCIATED WITH IMPULSES
MIGRATING ALONG/NEAR THE WESTERN PERIPHERY OF THE MID/UPPER RIDGE
ARE EXPECTED TO CONTRIBUTE TO NUMEROUS THUNDERSTORMS ACROSS THE
INTERMOUNTAIN WEST AND PARTS OF THE ROCKIES. MODELS ARE SUGGESTIVE
THAT ONE OF THESE IMPULSES WILL CONTRIBUTE TO CONVECTIVE DEVELOPMENT
ACROSS THE MOUNTAINS OF WESTERN MONTANA BY LATE TUESDAY
AFTERNOON/EVE. AND...SOME OF THESE STORMS ARE EXPECTED TO
EVENTUALLY DEVELOP NORTHEASTWARD INTO CENTRAL MONTANA TUESDAY
EVENING...AS THE BOUNDARY LAYER MOISTENS/DESTABILIZES IN THE WAKE OF
A COLD FRONT ASSOCIATED WITH THE VIGOROUS CANADIAN SHORT WAVE
TROUGH. DEEP LAYER SHEAR BENEATH WEAK TO MODERATE WEST
SOUTHWESTERLY MID-LEVEL FLOW MAY BE SUFFICIENT FOR SOME HAIL IN
STRONGER STORMS...ALONG WITH THE POTENTIAL FOR GUSTY WINDS IN SUB
CLOUD AIR WITH SIZABLE TEMPERATURE/DEW POINT SPREADS.
OTHERWISE...ENOUGH HEATING IS EXPECTED THROUGH THE INTERMOUNTAIN
WEST TO SUPPORT THE DEVELOPMENT OF A DEEPLY MIXED BOUNDARY LAYER
FAVORABLE FOR LOCALIZED DOWNBURSTS.
.KERR.. 07/23/2007
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