Prognostic Meteorological Discussion
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FXUS21 KWNC 211940
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 21 2014

SYNOPSIS: SURFACE HIGH PRESSURE OVER SOUTHEASTERN CANADA IS FORECAST TO KEEP
NEW ENGLAND COOL AND DRY DURING THE FIRST HALF OF THIS PERIOD.  A COLD FRONT IS
EXPECTED TO STRETCH FROM THE MID-ATLANTIC COAST TO THE CENTRAL PLAINS AND IS
PREDICTED TO BE THE FOCUS FOR PRECIPITATION.  SOUTH OF THIS FRONT, TEMPERATURES
ARE FORECAST TO BE ABOVE NORMAL WITH DAILY HIGHS WELL INTO THE 90S.

HAZARDS

MUCH ABOVE NORMAL TEMPERATURES FOR PARTS OF THE CENTRAL AND SOUTHERN PLAINS,
SUN-WED, AUG 24-27.

HEAVY RAIN FOR PARTS OF THE CENTRAL PLAINS AND GREAT LAKES, TUE-WED, AUG 26-27.

HEAVY RAIN FOR SOUTHERN FLORIDA, TUE-WED, AUG 26-27.

EXCESSIVE HEAT FOR PARTS OF THE MID-MISSISSIPPI VALLEY, SUN-WED, AUG 24-27.

EXCESSIVE HEAT FOR PARTS OF THE SOUTHEAST, SUN-MON, AUG 24-25.

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

DETAILED SUMMARY

FOR SUNDAY AUGUST 24 - THURSDAY AUGUST 28: A STRONG UPPER-LEVEL SHORTWAVE IS
FORECAST TO ROTATE AROUND THE BASE OF AN UPPER-LEVEL TROUGH THAT IS TO BE
CENTERED OVER THE NORTHWEST.  THE ASSOCIATED SURFACE COLD FRONT IS PREDICTED TO
BE THE FOCUS FOR HEAVY RAIN FROM PARTS OF THE CENTRAL PLAINS TO THE GREAT LAKES
ON THE 26TH AND 27TH WITH SOME LIGHT SNOW FOR THE TALLEST MOUNTAIN PEAKS IN THE
MOUNTAINS OF WYOMING NEAR YELLOWSTONE PARK.  IN ADDITION, LOCALIZED SEVERE
WEATHER IS POSSIBLE ACROSS THE CENTRAL PLAINS.



SOUTH OF THIS TROUGH, AN UPPER-LEVEL RIDGE IS EXPECTED TO DOMINATE THE WEATHER
DURING THIS PERIOD.  MUCH ABOVE NORMAL TEMPERATURES ARE FORECAST FOR PARTS OF
OKLAHOMA AND KANSAS WITH DAILY HIGH TEMPERATURE ANOMALIES OF AT LEAST 12
DEGREES F LIKELY.  THIS WOULD MEAN THE ACTUAL TEMPERATURES WOULD REACH CLOSE TO
100 DEGREES.  IN ADDITION, TWO AREAS ARE EXPECTED TO SEE A PERIOD OF EXCESSIVE
HEAT IN WHICH THE HEAT INDICES ARE EXPECTED TO BE FROM 105 TO 110 DEGREES.
THESE AREAS ARE THE PARTS OF THE SOUTHEAST AND NORTHERN FLORIDA AS WELL AS THE
MID-MISSISSIPPI VALLEY. BECAUSE THIS SUMMER HAS BEEN RELATIVELY COOL AND WE ARE
NEAR THE END OF THE SEASON, A HAZARD FOR EACH AREA WAS PLACED ON THE MAP.



THE TROPICAL EASTERN PACIFIC IS PREDICTED TO REMAIN VERY ACTIVE DURING THIS
PERIOD.  TROPICAL STORMS KARINA AND LOWELL ARE EXPECTED TO COME TOGETHER AND
ROTATE AROUND EACH OTHER IN WHAT IS KNOWN AS THE FUJIWHARA EFFECT.  HOWEVER,
THEY ARE FORECAST TO DO SO WELL OUT TO SEA AND NOT AFFECT LAND.  HOWEVER,
ANOTHER DISTURBANCE CURRENTLY OFF THE CENTRAL AMERICAN COAST IS PREDICTED BY
MOST NUMERICAL MODELS TO DEVELOP INTO A STRONG HURRICANE AND MOVE PARALLEL TO
THE BAJA CALIFORNIA COASTLINE.  IT IS UNCERTAIN AS TO WHETHER THIS SYSTEM WILL
DIRECTLY IMPACT THE UNITED STATES, BUT AS OF NOW, THE MOST LIKELY AFFECT WOULD
BE AN INCREASE IN THE INFLUX OF TROPICAL MOISTURE INTO THE WESTERN STATES.



IN THE TROPICAL ATLANTIC, AS OF 2PM EDT ON THURSDAY, THE NATIONAL HURRICANE
CENTER IS PREDICTING A 70% CHANCE OF A CURRENT DISTURBANCE FORMING INTO A
TROPICAL SYSTEM DURING THE NEXT FIVE DAYS.  TODAY`S NUMERICAL MODELS HAVE TAKEN
THIS FEATURE FARTHER TO THE NORTH THAN IN YESTERDAY`S RUNS, MEANING THAT THE
FORECAST TRACK WITH THE GREATEST PROBABILITY OF OCCURRING HAS THE SYSTEM MOVE
NORTH PARALLEL TO THE EASTERN FLORIDA COAST BEFORE CONTINUING NORTH AND EAST.
THIS TRACK WOULD MEAN THE SYSTEM WOULD DELIVER ITS GREATEST IMPACT ON BERMUDA.





FOR FRIDAY AUGUST 29 - THURSDAY SEPTEMBER 04: BEHIND THE COLD FRONT MOVING
THROUGH THE MIDDLE OF THE COUNTRY, COLD AIR COMING DOWN FROM CANADA COULD
CONTRIBUTE TO THE COLDEST MORNING IN MANY MONTHS ON AUG 29.  THE GEFS
REFORECAST TOOL PREDICTS A 10-20% CHANCE OF LOCATIONS FROM THE DAKOTAS TO
KANSAS SEEING MINIMUM TEMPERATURES BELOW FREEZING.  THE FORECAST CHANCE FOR
THIS OCCURRING DOES NOT MEET CRITERIA FOR INCLUSION ON THE PROBABILISTIC
HAZARDS MAP, BUT THIS POSSIBILITY SHOULD CONTINUE TO BE FOLLOWED AS IT WOULD BE
THE FIRST FREEZE OF THE SEASON ACROSS THESE LOCATIONS.



THE MOST RECENT U.S. DROUGHT MONITOR, RELEASED ON AUGUST 21, SHOWS THE
PERCENTAGE OF CONUS IN SEVERE DROUGHT DECREASING VERY SLIGHTLY FROM 22.03% TO
21.62%.

FORECASTER: KENNETH PELMAN

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