Prognostic Meteorological Discussion
Issued by NWS

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FXUS21 KWNC 241811
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 24 2016

SYNOPSIS: AT THE START OF THE PERIOD, A TROPICAL DISTURBANCE IS EXPECTED TO BE
APPROACHING SOUTHERN FLORIDA. THIS SYSTEM IS CURRENTLY ANTICIPATED TO DRIFT
SLOWLY WESTWARD INTO THE EASTERN GULF OF MEXICO THEN DRIFT NORTHWARD TOWARDS
THE CENTRAL GULF COAST. SURFACE HIGH PRESSURE OVER MAINE ON AUG 28 IS FORECAST
TO MOVE EASTWARD INTO THE NORTH ATLANTIC. SURFACE LOW PRESSURE NEAR THE ALASKA
PANHANDLE EARLY IN THE PERIOD BRINGS UNSETTLED WEATHER TO THE REGION.

HAZARDS

HEAVY RAIN FOR PARTS OF SOUTHERN AND EASTERN FLORIDA, SAT-TUE, AUG 27-30.

HEAVY RAIN FOR PARTS OF THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST, MON-WED,
AUG 29-31.

MUCH ABOVE NORMAL TEMPERATURES FOR PARTS OF THE OHIO VALLEY, GREAT LAKES,
NORTHEAST, AND CENTRAL APPALACHIANS, SUN AUG 28.

FLOODING POSSIBLE, OCCURRING OR IMMINENT ACROSS PORTIONS OF THE GREAT LAKES,
SOUTHERN PLAINS, AND THE MISSISSIPPI VALLEY.

SEVERE DROUGHT ACROSS PARTS OF THE EASTERN U.S., GREAT PLAINS, NORTHERN
ROCKIES, GREAT BASIN, ARIZONA, CALIFORNIA, EASTERN OREGON, AND HAWAII.

DETAILED SUMMARY

FOR SATURDAY AUGUST 27 - WEDNESDAY AUGUST 31: EARLY IN THE PERIOD A TROPICAL
DISTURBANCE IS FORECAST TO APPROACH SOUTHERN FLORIDA. THE DISTURBANCE IS THEN
EXPECTED TO DRIFT WESTWARD INTO THE EASTERN GULF OF MEXICO BY AUG 29, THEN
NORTHWARD TOWARDS THE CENTRAL GULF COAST BY AUG 31. THIS LEADS TO HEAVY RAIN
(IN EXCESS OF 1 INCH IN 24 HOURS) FOR PARTS OF SOUTHERN AND EASTERN FLORIDA AUG
27-30, AND FOR PARTS OF THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST AUG 29-31.
THE EXACT TRACK AND STRENGTH OF THE TROPICAL DISTURBANCE ARE HIGHLY UNCERTAIN
AT THIS TIME AND ADDITIONAL IMPACTS (HEAVY RAIN, FLOODING, ISOLATED TORNADOES,
HIGH WINDS, SIGNIFICANT WAVES, BEACH EROSION ETC.) ARE POSSIBLE FOR PARTS OF
THE SOUTHEAST AND GULF COAST. IN ADDITION, PARTS OF LOUISIANA ARE CURRENTLY
EXPERIENCING FLOODING SO THAT ADDITIONAL HEAVY RAINFALL WOULD EXTEND AND
EXACERBATE FLOODING CONCERNS. PLEASE CONSULT THE LATEST ADVISORIES FROM THE
NATIONAL HURRICANE CENTER AT HTTP://WWW.NHC.NOAA.GOV/.



SOUTHERLY FLOW AROUND THE WEST SIDE OF HIGH PRESSURE CENTERED OVER THE
NORTHEAST LEADS TO MUCH ABOVE NORMAL TEMPERATURES (POSITIVE ANOMALIES OF 10-12
DEGREES F) FOR PARTS OF THE OHIO VALLEY, GREAT LAKES, NORTHEAST, AND CENTRAL
APPALACHIANS AUG 28.



AT THE START OF THE PERIOD A FRONTAL SYSTEM STRETCHING ACROSS MUCH OF THE
CENTRAL CONUS IS EXPECTED TO MOVE NORTHWARD AS A WARM FRONT. SHOWERS AND
THUNDERSTORMS ASSOCIATED WITH THIS SYSTEM ARE FORECAST TO MOVE NORTHEASTWARD
FROM THE SOUTHERN PLAINS ON AUG 27 TO THE UPPER MISSISSIPPI VALLEY ON AUG 28.
RAINFALL AMOUNTS MAY BE LOCALLY HEAVY OVER PORTIONS OF THESE REGIONS.



ANTECEDENT RAINFALL, IN COMBINATION WITH ADDITIONAL RAINFALL EXPECTED DURING
THE PERIOD LEADS TO FLOODING POSSIBLE, IMMINENT, OR OCCURRING ACROSS PORTIONS
OF THE GREAT LAKES, SOUTHERN PLAINS, AND THE MISSISSIPPI VALLEY.



DESPITE DRY FUELS OVER MUCH OF THE WESTERN CONUS, WIND SPEEDS ARE FORECAST TO
LESSEN SO THAT CRITICAL FIRE WEATHER CONDITIONS ARE NOT CURRENTLY ANTICIPATED
EARLY IN THE PERIOD. LATER IN THE PERIOD, MODEL UNCERTAINTY IS TOO LARGE TO
SPECIFY A HAZARD SHAPE.

FOR THURSDAY SEPTEMBER 01 - WEDNESDAY SEPTEMBER 07: DURING WEEK-2 THE
CIRCULATION PATTERN IS EXPECTED TO FEATURE A TROUGH OVER THE WESTERN CONUS AND
ZONAL FLOW ACROSS THE MUCH OF THE NORTH-CENTRAL PART OF THE NATION. THIS
CIRCULATION PATTERN FAVORS BELOW-NORMAL TEMPERATURES OVER THE WESTERN CONUS.



THE ATLANTIC IS SHOWING INCREASED TROPICAL ACTIVITY AND SOME MODELS INDICATE
THE POSSIBILITY OF TROPICAL SYSTEMS NEAR THE EAST COAST OF THE U.S. OR THE GULF
OF MEXICO EARLY IN WEEK-2. THE EXACT EVOLUTION OF ANY TROPICAL SYSTEM IS
EXTREMELY UNCERTAIN THIS FAR OUT SO PLEASE CONSULT THE LATEST ADVISORIES FROM
THE NATIONAL HURRICANE CENTER AT HTTP://WWW.NHC.NOAA.GOV/.





ACCORDING TO THE U.S. DROUGHT MONITOR, THE COVERAGE OF SEVERE OR GREATER
DROUGHT DECREASED TO 7.71 PERCENT FROM 8.20 PERCENT. IMPROVEMENTS WERE REALIZED
ACROSS THE GREAT LAKES, GREAT PLAINS, AND THE LOWER MISSISSIPPI VALLEY.

FORECASTER: RANDY SCHECHTER

$$




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