922
FXUS21 KWNC 101813
PMDTHR
US HAZARDS ASSESSMENT
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EDT OCTOBER 10 2008
SYNOPSIS: EARLY IN THE ASSESSMENT PERIOD A WEAK COLD FRONT MOVES SOUTHWARD
ACROSS NEW ENGLAND, ALTHOUGH MOST OF THE EASTERN PART OF THE COUNTRY IS
DOMINATED BY HIGH PRESSURE. LOW PRESSURE, PARTIALLY ASSOCIATED WITH THE
REMNANTS OF HURRICANE NORBERT, MOVES FROM THE SOUTHERN PLAINS TO THE LOWER
MISSISSIPPI VALLEY. A COLD FRONT EXTENDS SOUTHWESTWARD FROM AN AREA OF LOW
PRESSURE OVER CENTRAL CANADA ACROSS THE UPPER AND MIDDLE MISSISSIPPI VALLEY TO
THE AREA OF LOW PRESSURE OVER THE SOUTHERN PLAINS. HIGH PRESSURE DOMINATES MOST
OF THE WESTERN CONUS ALTHOUGH A COLD FRONT MOVES ACROSS THE PACIFIC NORTHWEST
TO THE NORTHERN PLAINS. A PROLONGED STORMY PERIOD OCCURS FOR SOUTHERN ALASKA
AND THE ALASKAN PANHANDLE.
THE LOW OVER THE SOUTHERN PLAINS MOVES TO THE GREAT LAKES AND THEN NEW ENGLAND
AS ITS TRAILING COLD FRONT MOVES TO THE NORTHEAST STATES, MIDDLE ATLANTIC AND
OHIO VALLEY. THE SECOND COLD FRONT OVER THE NORTHERN PLAINS MOVES TO THE GREAT
LAKES, MIDDLE MISSISSIPPI VALLEY,CENTRAL PLAINS AND EXTENDS WESTWARD ACROSS THE
CENTRAL ROCKIES TO THE CENTRAL GREAT BASIN. BY MID-PERIOD THE FRONT OVER THE
GREAT LAKES AND CENTRAL CONUS MOVES TO NEW ENGLAND AND STRETCHES BACK WESTWARD
ACROSS THE OHIO VALLEY, MIDDLE MISSISSIPPI VALLEY TO THE SOUTHERN PLAINS. HIGH
PRESSURE DOMINATES MOST OF THE REST OF THE CONUS ALTHOUGH ANOTHER COLD FRONT
MOVES FROM THE EASTERN PACIFIC TO THE PACIFIC NORTHWEST. FOR THE LONGER RANGES,
A STORMY PATTERN IS EXPECTED TO CONTINUE OVER THE GULF OF ALASKA WHILE THE
CONUS IS MOSTLY DOMINATED BY A WEST TO EAST FLOW PATTERN.
HAZARDS
RIVER FLOODING FOR THE RED RIVER VALLEY OCT 13.
HEAVY RAIN FOR THE UPPER AND MIDDLE MISSISSIPPI VALLEY AND CENTRAL AND SOUTHERN
PLAINS OCT 13-14.
CRITICAL FIRE WEATHER FOR COASTAL CENTRAL AND SOUTHERN CALIFORNIA DUE TO
STRENGTHENING OFFSHORE WINDS OCT 13-14.
ONGOING RIVER FLOODING WILL CONTINUE ACROSS PORTIONS OF TEXAS ON THE RIO GRANDE
NEAR DEL RIO.
FLOODING DUE TO RAINFALL FROM THE REMNANTS OF HURRICANE NORBERT FOR
SOUTHWESTERN TEXAS OCT 13.
MUCH ABOVE NORMAL TEMPERATURES NEAR THE GREAT LAKES, OHIO VALLEY, MID-ATLANTIC
AND NORTHEAST OCT 13-14.
MUCH BELOW NORMAL TEMPERATURES FOR PARTS OF THE NORTHERN GREAT BASIN, THE
NORTHERN ROCKIES, AND NORTHERN PLAINS OCT 13.
HEAVY COASTAL RAINS AND INLAND SNOW FOR SOUTHERN ALASKA AND THE ALASKAN
PANHANDLE OCT 13-17.
SEVERE DROUGHT WILL CONTINUE FOR PARTS OF THE WESTERN US, SOUTHEAST, NORTHERN
PLAINS, SOUTHERN PLAINS AND UPPER MISSISSIPPI VALLEY WITH SOME RELIEF LIKELY
OVER PARTS OF THE NORTHERN AND SOUTHERN PLAINS, AND THE UPPER MISSISSIPPI
VALLEY.
DETAILED SUMMARY
FOR MONDAY OCTOBER 13 - WEDNESDAY OCTOBER 15: A WARM FRONT MOVES NORTHWARD
ACROSS THE GREAT LAKES. THIS LEADS TO MUCH ABOVE NORMAL TEMPERATURES FOR THE
GREAT LAKES, OHIO VALLEY, MID-ATLANTIC AND NORTHEAST. THE WARM FRONT EXTENDS
NORTHWESTWARD TO A LOW OVER CENTRAL CANADA.
ANTECEDENT PRECIPITATION ASSOCIATED WITH THIS AREA OF LOW PRESSURE CAUSES
FLOODING OVER THE RED RIVER VALLEY. THE TRAILING COLD FRONT BEHIND THE LOW, IN
COMBINATION WITH MOISTURE SPREADING NORTHWARD (IN ASSOCIATION WITH THE REMANTS
OF HURRICANE NORBERT), BRINGS HEAVY PRECIPITATION TO THE UPPER AND MIDDLE
MISSISSIPPI VALLEY AND CENTRAL AND SOUTHERN PLAINS. THIS MAY CAUSE FLOODING
OVER SOUTHWEST TEXAS. THE RAINFALL ALSO OFFERS SOME RELIEF TO THE DROUGHT AREAS
OF THE NORTHERN AND SOUTHERN PLAINS AND UPPER MISSISSIPPI VALLEY. NORTHERLY
FLOW BEHIND THE COLD FRONT LEADS TO AN AREA OF MUCH BELOW NORMAL TEMPERATURES
FOR PARTS OF THE NORTHERN GREAT BASIN, THE NORTHERN ROCKIES, AND NORTHERN
PLAINS.
HIGH PRESSURE DOMINATES MUCH OF THE WESTERN CONUS AND WILL GENERATE OFFSHORE
FLOW OVER CALIFORNIA. THIS LEADS TO THE THREAT OF CRITICAL FIRE WEATHER
CONDITIONS OVER COASTAL CENTRAL AND SOUTHERN CALIFORNIA. A STORMY PATTERN IS
EXPECTED FOR SOUTHERN ALASKA LEADING TO COASTAL HEAVY RAIN AND INLAND HEAVY
SNOW OVER SOUTHERN ALASKA AND THE ALASKAN PANHANDLE. RIVER FLOODING IS LIKELY
ALONG PORTIONS OF THE RIO GRANDE NEAR DEL RIO AND JOHNSON RANCH DUE TO
SURCHARGE RELEASES FROM LAKE AMISTAD. DROUGHT IS ONGOING OVER THE SOUTHEAST AND
OVER CALIFORNIA AND NEVADA.
FOR THURSDAY OCTOBER 16 - MONDAY OCTOBER 20: TWO COLD FRONTS SWEEP ACROSS THE
NORTHEAST STATES BUT LIMITED MOISTURE IS AVAILABLE TO PRODUCE MUCH IN THE WAY
OF PRECIPITATION. HIGH PRESSURE DOMINATES MOST OF THE WESTERN CONUS WHILE A
STORMY PATTERN CONTINUES OVER SOUTHERN ALASKA AND THE ALASKAN PANHANDLE.
FIVE-DAY MEAN FORECASTS INDICATE A MOSTLY ZONAL FLOW PATTERN ACROSS THE CONUS.
FOR TUESDAY OCTOBER 21 - FRIDAY OCTOBER 24: UPPER LEVEL TROUGHS ARE FORECAST
OVER THE NORTHEASTERN PART OF THE COUNTRY AND THE GULF OF ALASKA WHILE A RIDGE
IS PROGGED OVER THE WEST-CENTRAL CONUS. THE LACK OF PREDICTABILITY AT THIS TIME
RANGE PRECLUDES THE FORECAST OF SPECIFIC HAZARDS.
FORECASTER: RANDY SCHECHTER
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