US HAZARDS ASSESSMENT
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300
PM EDT JULY 02 2009
SYNOPSIS: A WEAK FLOW OF HUMID AIR FROM THE
GULF OF MEXICO IS FORECAST TO BRING SULTRY WEATHER FOR MUCH OF THE SOUTH EARLY
IN THE PERIOD, WHILE LOW PRESSURE AND COOL, DAMP WEATHER PERSISTS IN THE
NORTHEAST. LOW PRESSURE ASSOCIATED WITH A NEARLY-STATIONARY FRONT IS FORECAST
TO BRING HEAVY RAIN FROM THE CENTRAL STATES THROUGH THE SOUTHEAST. A LARGE AREA
OF UPPER-LEVEL HIGH PRESSURE IS FORECAST TO EXPAND OVER THE CENTER OF THE
COUNTRY TOWARD THE END OF NEXT WEEK, BRINGING MUCH ABOVE-NORMAL TEMPERATURES TO
THE CENTRAL PLAINS.
HAZARDS - MUCH ABOVE-NORMAL TEMPERATURES FOR THE
CENTRAL PLAINS JULY 9-13.
- HEAVY RAINS IN NEW ENGLAND JULY 5-8.
- ONGOING FLOODING FOR PARTS OF EASTERN SOUTH DAKOTA.
- HEAVY RAINS FOR THE TENNESSEE VALLEY JULY 5-7.
- SEVERE THUNDERSTORMS FROM ARKANSAS TO THE CAROLINAS JULY 5-6.
- PERSISTING DROUGHT ACROSS PARTS OF CALIFORNIA, NEVADA, NEW MEXICO, AND
TEXAS, BUT SOME IMPROVEMENT IN NORTHERN WISCONSIN.
DETAILED
SUMMARYFOR SUNDAY JULY 05 - TUESDAY JULY 07:
AN UPPER-LEVEL TROUGH IS FORECAST TO PERSIST OVER THE NORTHEAST, WHILE A
NEARLY-STATIONARY FRONT EXTENDS FROM TEXAS TO THE SOUTHEAST COAST. MORE RAIN IS
EXPECTED TO FALL ON GROUND THAT IS ALREADY SATURATED IN NEW ENGLAND. LOW
PRESSURE ON THE FRONT TO THE SOUTH IS FORECAST TO TRAVEL FROM ARKANSAS ON JULY
5 TO THE CAROLINAS ON JULY 7. THE LOW IS FORECAST TO BRING HEAVY RAINS FROM
MISSOURI AND ARKANSAS TO THE CAROLINAS, WITH THE POTENTIAL FOR SEVERE WEATHER
ON SUNDAY AND MONDAY FROM ARKANSAS THROUGH TENNESSEE, NORTHERN PARTS OF
MISSISSIPPI, ALABAMA, AND GEORGIA, AND INTO THE WESTERN CAROLINAS. SOUTH OF THE
FRONT, MAXIMUM HEAT INDICES ON SUNDAY ARE FORECAST TO REACH 105 DEGREES F FROM
TEXAS INTO GEORGIA. ON THE WEST COAST, A WEAKENING UPPER-LEVEL RIDGE WILL ALLOW
A COLD FRONT TO SUPPLY COOLER AIR TO THE PACIFIC STATES.
A RELATIVELY TRANQUIL WEATHER PATTERN PREVAILS IN ALASKA, AS A BERING SEA
LOW PRESSURE CENTER IS FORECAST TO TRACK NORTHWARD WHILE A COLD FRONT
DISSIPATES OVER THE INTERIOR.
FOR WEDNESDAY JULY 08 - SUNDAY
JULY 12: THE UPPER-LEVEL TROUGH IS EXPECTED TO BRING MORE RAIN TO SOGGY NEW
ENGLAND THROUGH JULY 8. THE NEARLY-STATIONARY FRONT ACROSS THE SOUTH IS
FORECAST TO DISSIPATE. THE UPPER LEVEL TROUGH IN THE NORTHWEST IS EXPECTED TO
BRING UNSEASONABLY COOL AIR TO THE WEST, WHILE SURFACE LOW PRESSURE AND A
SOUTHWARD-EXTENDED COLD FRONT SLOWLY EDGE EASTWARD ACROSS THE NORTHERN PLAINS,
BRINGING RAIN TO THE REGION. BY JULY 11, BENEFICIAL MOISTURE IS FORECAST FOR
THE UPPER MIDWEST, INCLUDING THE LONG-TERM DROUGHT AREA IN WISCONSIN. CANADIAN
HIGH PRESSURE IS FORECAST TO BRING COOL AIR TO THE MIDWEST EARLY IN THE PERIOD
AND THEN SLOWLY SHIFT EASTWARD.
UPPER-LEVEL HIGH PRESSURE IS FORECAST TO EXPAND ACROSS THE PLAINS DURING
THIS PERIOD, BRINGING ABNORMAL HEAT TO THE CENTRAL PLAINS AND PORTIONS OF THE
NORTHERN AND SOUTHERN PLAINS AS WELL. THE HEAT IS MAINLY A THREAT FROM NEBRASKA
SOUTHWARD TO OKLAHOMA STARTING AROUND JULY 9 AND CONTINUING FOR AT LEAST
SEVERAL DAYS. THERE CONTINUES TO BE UNUSUALLY GOOD AGREEMENT AMONG MODELS AND
GFS ENSEMBLE MEMBERS ON THE AMPLIFICATION OF THE PLAINS RIDGE. HOWEVER, THERE
IS DISAGREEMENT ON THE EASTWARD EXTENT OF THE RIDGE. IN A REVERSAL FROM EARLIER
FORECASTS, LAST NIGHT'S OPERATIONAL ECMWF MODEL SHOWS A STRONG RIDGE CENTERED
OVER THE CENTRAL PLAINS DOMINATING MUCH OF THE COUNTRY BY JULY 11 WHILE THE
MOST RECENT GFS SOLUTIONS ARE SOMEWHAT WEAKER. AS A RESULT, THERE IS SOME
UNCERTAINTY ABOUT THE NORTHWARD AND EASTWARD EXTENT OF THE ABNORMAL HEAT.
IN THE ALASKA REGION, WEAK LOWS ARE EXPECTED TO ROTATE AROUND HIGH PRESSURE
DOMINATING THE GULF OF ALASKA.
FOR MONDAY JULY 13 - THURSDAY
JULY 16: A MAJORITY OF MODELS SHOW A CONTINUATION OF THE UPPER-LEVEL
PATTERN FEATURING TROUGHING ALONG THE WEST AND EAST COASTS AND RIDGING IN THE
MIDDLE. THE ABNORMAL HEAT IN THE PLAINS IS EXPECTED TO PERSIST AT LEAST INTO
THE EARLY PART OF THIS PERIOD.
FORECASTER: DOUG LECOMTE
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