169
FXUS21 KWNC 062111
PMDTHR
US HAZARDS ASSESSMENT
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EST NOVEMBER 06 2009
SYNOPSIS: THE ASSESSMENT PERIOD IS EXPECTED TO FEATURE ACTIVE WEATHER ACROSS
THE GULF COAST, SOUTHEAST, PACIFIC NORTHWEST, AND PORTIONS OF ALASKA. A WEAK
LOW-PRESSURE SYSTEM IS EXPECTED TO TRAVERSE THE NORTHERN TIER OF THE COUNTRY
WITH AN ASSOCIATED COLD FRONT MOVING FROM THE GREAT PLAINS TO THE EASTERN
SEABOARD BY THE MIDDLE OF NEXT WEEK. LATE SEASON INFLUENCES OF A TROPICAL
NATURE COULD AFFECT THE SOUTHEAST. ANOTHER, MORE POTENT LOW-PRESSURE SYSTEM,
IS EXPECTED TO MOVE ONSHORE ACROSS THE PACIFIC NORTHWEST. DURING THE MIDDLE
PORTIONS OF THE ASSESSMENT PERIOD, THE PRIMARY AREA OF UNSETTLED WEATHER IS
EXPECTED TO SHIFT TO THE CENTRAL PORTIONS OF THE COUNTRY, AS A LOW-PRESSURE
SYSTEM DEVELOPS EAST OF THE CENTRAL ROCKIES AND MOVES NORTHEAST ACROSS THE
GREAT PLAINS. THE EASTERN THIRD OF THE COUNTRY SHOULD COME UNDER THE CALMING
INFLUENCE OF HIGH PRESSURE. THE FOCUS OF ACTIVE WEATHER ACROSS ALASKA IS
EXPECTED TO SHIFT FROM SOUTHEAST ALAKSA TO WESTERN ALASKA AND THE ALEUTIANS.
HAZARDS
ONGOING FLOODING FOR PARTS OF THE CENTRAL AND SOUTHERN MISSISSIPPI VALLEY, AS
WELL AS FOR EASTERN PORTIONS OF TEXAS.
HEAVY PRECIPITATION FOR THE PACIFIC NORTHWEST, NOV 9.
PERIODS OF HEAVY PRECIPITATION FOR SOUTHEAST ALASKA, NOV 9-10, 12-13.
HEAVY PRECIPITATION FOR PORTIONS OF THE SOUTHEAST, NOV 9-12.
HEAVY PRECIPITATION FOR WESTERN ALASKA, NOV 11-12.
SEVERE DROUGHT CONTINUES IN PARTS OF WISCONSIN, TEXAS, ARIZONA, NEW MEXICO,
CALIFORNIA, NEVADA, AND WASHINGTON. SOME RELIEF IS EXPECTED ACROSS WISCONSIN,
WASHINGTON, NORTHERN CALIFORNIA, AND SOUTH CAROLINA.
DETAILED SUMMARY
FOR MONDAY NOVEMBER 09 - WEDNESDAY NOVEMBER 11: A RIDGE OF HIGH PRESSURE IS
FORECAST ALONG THE EAST COAST. ON THE SOUTHERN FLANK OF THIS RIDGE, STRONG
EASTERLIES ACROSS MOST OF THE EAST COAST OF FLORIDA AND PORTIONS OF GEORGIA ARE
EXPECTED TO PERSIST THROUGH MONDAY, NOVEMBER 9. WINDS RANGING FROM 20-30 MPH
ARE POSSIBLE, WITH THE HIGHEST WINDS FURTHER SOUTH. THIS TYPE OF WEATHER
PATTERN IS ALSO ASSOCIATED WITH DANGEROUS RIP CURRENTS, MINOR COASTAL EROSION,
AND RED FLAG WARNINGS ACROSS FLORIDA. CONCERNED PARTIES SHOULD CONTACT THE
LOCAL WEATHER FORECAST OFFICE FOR MORE INFORMATION.
A SURGE OF TROPICAL MOISTURE, INTERACTING WITH THE COLD FRONT THAT IS EXPECTED
TO MOVE INTO THE SOUTHEAST, SHOULD PROVIDE SIGNIFICANT RAINFALL TO PORTIONS OF
THE SOUTHEAST. ADDITIONALLY, MOISTURE ASSOCIATED WITH TROPICAL STORM IDA
SHOULD PROVIDE A SECOND MOISTURE SURGE. CONSULT FORECAST PRODUCTS FROM THE
NATIONAL HURRICANE CENTER (WWW.NHC.NOAA.GOV) FOR MORE INFORMATION ON THE TRACK
AND INTENSITY OF TROPICAL STORM IDA.
HIGH PRESSURE TO THE NORTH SHOULD LIMIT THE NORTHWARD PROGRESSION OF THE
MOISTURE ACROSS THE SOUTHEAST, POTENTIALLY CAUSING FLOODING RAINS ACROSS
ALABAMA, GEORGIA, AND FLORIDA. CONTACT YOUR LOCAL WEATHER FORECAST OFFICE AND
HEED WARNINGS FROM LOCAL AUTHORITIES.
FURTHER NORTH, ON THE EASTERN FLANK OF THE HIGH PRESSURE THAT IS FORECAST TO
BUILD IN BEHIND THE COLD FRONT, WINDY CONDITIONS ARE LIKELY ACROSS THE
NORTHEAST WEDNESDAY NOVEMBER 11.
ACROSS THE PACIFIC NORTHWEST, A POTENT LOW-PRESSURE SYSTEM IS FORECAST TO MOVE
ONSHORE IN BRITISH COLUMBIA DURING THE DAY ON NOVEMBER 9. RAINFALL AMOUNTS
COULD EXCEED 3 INCHES ACROSS SOME PARTS OF WASHINGTON AND OREGON, BEFORE THE
RAINS ABATE DURING THE DAY ON NOVEMBER 10.
MULTIPLE STORM SYSTEMS ARE FORECAST TO IMPACT ALASKA WITH A STRONG COLD FRONT
FORECAST TO MOVE ACROSS WESTERN ALASKA AND THE ALEUTIANS NOVEMBER 10. BEHIND
THAT COLD FRONT, WIND SPEEDS BETWEEN 30 AND 40 MPH ARE POSSIBLE IN ISOLATED
PLACES, WITH MOST WIND SPEEDS NOT MEETING HAZARD CRITERIA. A SECOND
LOW-PRESSURE SYSTEM IS FORECAST TO DEVELOP ON THE WESTERN END OF THAT COLD
FRONT, BRINGING SIGNIFICANT PRECIPITATION AND BLOWING SNOW ACROSS WESTERN
ALASKA THROUGH NOVEMBER 12.
FOR THURSDAY NOVEMBER 12 - MONDAY NOVEMBER 16: A SHORTWAVE IS FORECAST TO MOVE
SOUTHWARD ALONG THE PACIFIC COAST DURING THE MIDDLE OF NEXT WEEK. UNCERTAINTY
ABOUT THE STRENGTH OF SURFACE REFLECTION OF THAT SHORTWAVE IS HIGH, AS THE 12Z
ECMWF SOLUTION DEPICTS A 1006MB LOW JUST WEST OF PUGET SOUND WHILE THE 12Z GFS
SOLUTION DEPICTS RIDGING, AND A MUCH WEAKER SHORTWAVE. PRECIPITATION AMOUNTS
INDICATED IN THE MODEL SOLUTIONS VARY GREATLY AS A RESULT OF THE VARIANCE IN
STRUCTURE, THEREFORE NO HAZARD IS DEPICTED DUE TO HIGH UNCERTAINTY IN THE
TIMING OF THE FEATURES.
BOTH MODELS DO COME INTO BETTER AGREEMENT ON THE DEVELOPMENT OF A LOW-PRESSURE
SYSTEM ACROSS THE CENTRAL ROCKIES DURING THE MIDDLE OF NEXT WEEK. BOTH MODELS
INDICATE THAT THE LOW-PRESSURE SYSTEM SHOULD MOVE INTO THE CENTRAL GREAT
PLAINS, BUT VARY WIDELY ON THE AMOUNT OF PRECIPITATION. GIVEN THE LOCATION OF
THE LOW-PRESSURE SYSTEM AND WIND DIRECTION, SIGNIFICANT OROGRAPHIC ENHANCEMENT
OF PRECIPITATION IS LIKELY ACROSS WYOMING , IDAHO AND NORTHERN COLORADO, BUT A
BROADER HAZARD CANNOT BE DEPICTED DUE TO UNCERTAINTY IN THE FORECAST.
THE SECOND LOW-PRESSURE SYSTEM MOVING ACROSS ALASKA IS EXPECTED TO MOVE INTO
THE GULF OF ALASKA LATE NEXT WEEK, AND SHOULD BRING ANOTHER ROUND OF HEAVY
PRECIPITATION TO SOUTHEAST ALASKA AND THE ALASKAN PANHANDLE.
FOR TUESDAY NOVEMBER 17 - FRIDAY NOVEMBER 20: A STRONG TROUGH IS FORECAST TO
EXTEND FROM CENTRAL ALASKA TO THE EASTERN PACIFIC WITH RIDGING PRESENT FROM THE
FOUR CORNERS REGION TO THE GREAT LAKES. THIS PATTERN IS EXPECTED TO SUPPORT
WET CONDITIONS ACROSS SOUTHEASTERN ALASKA, THE WEST COAST AND FROM THE SOUTHERN
PLAINS TO THE MID-ATLANTIC. WARMER THAN AVERAGE CONDITIONS ARE EXPECTED ACROSS
THE NORTHERN TIER OF THE COUNTRY.
SEVERE DROUGHT IS EXPECTED TO PERSIST ACROSS CALIFORNIA, NEVADA, ARIZONA, AND
NEW MEXICO. SOME DROUGHT RELIEF IS EXPECTED ACROSS WISCONSIN, TEXAS, NORTHERN
CALIFORNIA, AND SOUTH CAROLINA.
FORECASTER: MATT ROSENCRANS
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