Prognostic Meteorological Discussion
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FXUS21 KWNC 301836
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SEPTEMBER 30 2014

SYNOPSIS: SURFACE LOW PRESSURE OVER THE NORTHERN GREAT LAKES IS FORECAST TO
MOVE INTO SOUTHERN CANADA AS ITS TRAILING COLD FRONT MOVES EASTWARD ACROSS THE
EAST-CENTRAL U.S. AND OFF THE EAST COAST. A SECOND AREA OF LOW PRESSURE IS
FORECAST TO FORM ON THE FRONT OVER THE MID-ATLANTIC AND MOVE TOWARDS NEW
ENGLAND. SURFACE LOW PRESSURE IS EXPECTED OVER THE GULF OF ALASKA AND
SOUTHEASTERN ALASKA AS ANOTHER AREA OF LOW PRESSURE APPROACHES THE ALEUTIANS.

HAZARDS

HIGH WINDS FOR PARTS OF THE NORTHERN PLAINS, UPPER MISSISSIPPI VALLEY, AND
GREAT LAKES, FRI-SAT, OCT 3-4.

HEAVY RAIN FOR PARTS OF THE NORTHEAST, FRI-SAT, OCT 3-4.

HEAVY RAIN FOR SOUTHERN PARTS OF THE ALASKA PANHANDLE, FRI, OCT 3.

FLOODING OCCURRING OR IMMINENT FOR PARTS OF WEST-CENTRAL FLORIDA.

SEVERE DROUGHT FOR THE CENTRAL AND SOUTHERN GREAT PLAINS, SOUTHWEST, SOUTHERN
GEORGIA, PACIFIC NORTHWEST, GREAT BASIN, AND CALIFORNIA.

DETAILED SUMMARY

FOR FRIDAY OCTOBER 03 - TUESDAY OCTOBER 07: STRONG SURFACE LOW PRESSURE OVER
THE NORTHERN GREAT LAKES IS FORECAST TO MOVE INTO SOUTHERN CANADA AS A SECOND
AREA OF LOW PRESSURE FORMS ON ITS TRAILING COLD FRONT. THIS IS EXPECTED TO
CAUSE HEAVY RAIN (IN EXCESS OF 1 INCH IN A 24-HOUR PERIOD) FOR PARTS OF THE
NORTHEAST FRI-SAT. THE TIGHT PRESSURE GRADIENT BEHIND THE DEPARTING AREA OF LOW
PRESSURE IS FORECAST TO LEAD TO HIGH WINDS (IN EXCESS OF 30 KNOTS) FOR PARTS OF
THE NORTHERN PLAINS, UPPER MISSISSIPPI VALLEY, AND GREAT LAKES FRI-SAT.



ANTECEDENT RAINFALL WILL CAUSE FLOODING FOR PARTS OF WEST-CENTRAL FLORIDA.



AN AREA OF DEEP LOW PRESSURE OVER THE GULF OF ALASKA FAVORS HEAVY RAIN (IN
EXCESS OF 2 INCHES IN A 24-HOUR PERIOD) FOR SOUTHERN PARTS OF THE ALASKA
PANHANDLE FRI. THIS AREA HAS RECENTLY HAD HEAVY RAINFALL SO MUDSLIDES ARE
POSSIBLE FOR THE REGION.



UPPER-LEVEL RIDGING IS PREDICTED FOR THE WEST COAST, WITH SURFACE HIGH PRESSURE
MOVING INTO THE FOUR CORNERS REGION.  THIS SETUP FAVORS STRONG DOWNSLOPE WINDS
FOR MOST OF CALIFORNIA.  THESE WINDS ARE FORECAST TO INCREASE THE DAYTIME
MAXIMUM TEMPERATURES INTO THE LOW 90S FOR INLAND PARTS OF SOUTH-CENTRAL
CALIFORNIA, WITH ISOLATED LOCALES SEEING HIGHER VALUES.  HOWEVER, THE FORECAST
TEMPERATURE ANOMALIES DO NOT WARRANT A HAZARD AT THIS TIME.  DESPITE THE
COMBINATION OF WARM TEMPERATURES, GUSTY WINDS, AND DRY SOILS, NO ENHANCED RISK
OF WILDFIRES IS INDICATED DUE TO UNCERTAINTY IN THE STRENGTH OF THESE
ANTICIPATED DOWNSLOPE WINDS.

FOR WEDNESDAY OCTOBER 08 - TUESDAY OCTOBER 14: A MODERATELY AMPLIFIED FLOW
PATTERN IS ANTICIPATED FOR MUCH OF THE CONUS DURING THE PERIOD. A TROUGH IS
PREDICTED OVER THE EAST-CENTRAL CONUS. DEEP LOW PRESSURE IS FORECAST TO
APPROACH THE ALEUTIANS AND WESTERN ALASKA EARLY IN THE PERIOD, BUT MODEL
UNCERTAINTY PRECLUDES THE SPECIFICATION OF HAZARD AREAS AT THE CURRENT TIME.



THE U.S. DROUGHT MONITOR, VALID ON SEPTEMBER 23, INDICATES THAT THE PERCENTAGE
OF THE CONUS IN SEVERE TO EXCEPTIONAL DROUGHT DECREASED TO BELOW 19 PERCENT.

FORECASTER: RANDY SCHECHTER

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