Prognostic Meteorological Discussion
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FXUS21 KWNC 151805
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SEPTEMBER 15 2014

SYNOPSIS: MAJOR HURRICANE ODILE MADE LANDFALL NEAR CABO SAN LUCAS, MEXICO ON
SUNDAY NIGHT. THE REMNANTS OF ODILE ARE EXPECTED TO TRACK NORTHEAST AND ENTER
THE SOUTHWEST LATER THIS WEEK. SURFACE HIGH PRESSURE, CENTERED OVER NEW ENGLAND
ON FRIDAY MORNING, IS FORECAST TO SHIFT OFFSHORE OF THE EAST COAST. A COLD
FRONT IS FORECAST TO PROGRESS FROM THE GREAT PLAINS ON FRIDAY TO THE EASTERN
U.S. BY EARLY NEXT WEEK. AN AREA OF UPPER-LEVEL LOW PRESSURE IS FORECAST TO
PERSIST ACROSS ALASKA DURING THE NEXT TWO WEEKS.

HAZARDS

FLASH FLOODING POSSIBLE FOR MUCH OF THE SOUTHWEST, THU-FRI, SEP 18-19.

HEAVY RAIN FOR PARTS OF PARTS OF THE SOUTHERN GREAT PLAINS AND OZARKS REGION,
SAT-SUN, SEP 20-21.

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

DETAILED SUMMARY

FOR THURSDAY SEPTEMBER 18 - MONDAY SEPTEMBER 22: ABNORMALLY HIGH MOISTURE,
ASSOCIATED WITH THE REMNANTS OF HURRICANE ODILE, IS FORECAST TO INTERACT WITH A
SHORTWAVE TROUGH AND RESULT IN HEAVY RAINFALL AND FLASH FLOODING ACROSS THE
SOUTHWEST ON THURSDAY AND FRIDAY. THE MOST LIKELY AREA FOR FLASH FLOODING IS
EXPECTED FROM ARIZONA EAST TO THE SOUTHWEST AND SOUTH CENTRAL MOUNTAINS OF NEW
MEXICO. THE 6Z GFS DETERMINISTIC MODEL INDICATES THAT PRECIPITABLE WATER VALUES
PEAK AT MORE THAN 2 INCHES ON WEDNESDAY BUT REMAIN HIGH FOR SEPTEMBER THROUGH
FRIDAY.



A COLD FRONT IS EXPECTED TO CROSS THE EAST-CENTRAL U.S. FROM FRIDAY THROUGH
SUNDAY. IT REMAINS UNCLEAR AT THIS TIME WHERE THE REMNANT MOISTURE ASSOCIATED
WITH ODILE BECOMES ENTRAINED WITHIN THE WESTERLY FLOW ALOFT. SINCE THE COLD
FRONT IS EXPECTED TO SLOW AND INTERACT WITH ABUNDANT GULF MOISTURE, A HEAVY
RAIN HAZARD IS POSTED FOR PARTS OF THE SOUTHERN GREAT PLAINS AND OZARKS REGION
DURING THE WEEKEND. SEVERE THUNDERSTORMS COULD DEVELOP ALONG AND AHEAD OF THE
COLD FRONT AS IT CROSSES THE GREAT PLAINS AND MISSISSIPPI VALLEY, BUT
UNCERTAINTY REGARDING TIMING PRECLUDES DESIGNATION OF A SEVERE WEATHER HAZARD
AT THIS TIME.



LONG PERIOD SWELLS ASSOCIATED WITH HURRICANE EDOUARD OVER THE ATLANTIC ARE
EXPECTED TO AFFECT THE SOUTHEAST COAST THIS WEEK. IN ADDITION, AN INCREASE IN
ONSHORE WINDS ARE FORECAST AS A SURFACE HIGH BUILDS NEAR NEW ENGLAND. THESE
ONSHORE WINDS ARE EXPECTED TO MAINTAIN ELEVATED SEAS AND THE THREAT OF RIP
CURRENTS FOR BEACHES ALONG THE SOUTHEAST COAST THROUGH THE WEEKEND.



AS A STRONG SURFACE HIGH BECOMES CENTERED OVER NEW ENGLAND ON FRIDAY MORNING,
WIDESPREAD FROST OR A LIGHT FREEZE ARE LIKELY PARTS OF NEW ENGLAND AND UPSTATE
NEW YORK. SINCE MINIMUM TEMPERATURES ARE FORECAST TO AVERAGE AROUND 8 DEGREES F
BELOW-NORMAL, A MUCH BELOW-NORMAL HAZARD IS NOT POSTED DUE TO NOT REACHING
ANOMALY THRESHOLDS.



AN UPPER-LEVEL RIDGE IS EXPECTED TO RESULT IN MAXIMUM TEMPERATURES AVERAGING
AROUND 12 DEGREES F ABOVE-NORMAL ACROSS THE INTERIOR PACIFIC NORTHWEST ON
SUNDAY AND MONDAY. SINCE MAXIMUM TEMPERATURES ARE FORECAST TO REMAIN BELOW 90
DEGREES F, A MUCH-ABOVE NORMAL TEMPERATURE HAZARD IS NOT DEEMED NECESSARY FOR
THIS REGION.



A MODERATELY STRONG SURFACE LOW (AROUND 980-HPA) IS FORECAST TO BE LOCATED OVER
THE NORTHERN GULF OF ALASKA ON THURSDAY. ALTHOUGH LOCALLY HEAVY PRECIPITATION
AND GUSTY WINDS ARE EXPECTED TO BE ASSOCIATED WITH THIS SURFACE LOW, THE
PRECIPITATION AMOUNTS AND WIND SPEEDS ARE EXPECTED TO REMAIN BELOW HAZARDS
CRITERIA AT THIS TIME.

FOR TUESDAY SEPTEMBER 23 - MONDAY SEPTEMBER 29: ENSEMBLE MEANS INDICATE A
TROUGH OVER ALASKA AND THE EASTERN U.S. WITH A RIDGE ACROSS THE WESTERN U.S.,
BUT THE 0Z/6Z GFS AND 0Z ECMWF ENSEMBLE MEANS DIFFER ON THE AMPLITUDE OF THE
LONGWAVE PATTERN.



A BROAD AREA OF LOW PRESSURE IS CURRENTLY LOCATED SEVERAL HUNDRED MILES SOUTH
OF ACAPULCO, MEXICO. AS OF 8AM EDT ON MONDAY, THE NATIONAL HURRICANE CENTER
STATES THAT THIS DISTURBANCE HAS A 70 PERCENT CHANCE OF TROPICAL CYCLONE
DEVELOPMENT DURING THE NEXT 5 DAYS. ANOTHER SURGE OF TROPICAL MOISTURE COULD
SPREAD NORTH INTO THE DESERT SOUTHWEST DURING WEEK-2 DEPENDING ON THE TRACK OF
THIS SYSTEM.



THE MOST RECENT U.S. DROUGHT MONITOR, RELEASED LAST THURSDAY, INDICATES THE
PERCENTAGE OF THE CONUS IN SEVERE TO EXCEPTIONAL DROUGHT DECREASING FROM THE
PREVIOUS WEEK`S (SEPTEMBER 4) 20.93 PERCENT TO 20.31 PERCENT. THIS IS ALSO DOWN
SUBSTANTIALLY FROM BOTH 2013 AND 2012 AT THIS TIME OF YEAR (32.40 AND 42.48
PERCENT, RESPECTIVELY).

FORECASTER: BRAD PUGH

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