Prognostic Meteorological Discussion
Issued by NWS

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FXUS21 KWNC 261816
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 26 2016

SYNOPSIS: AT THE START OF THE PERIOD, A TROPICAL DISTURBANCE IS EXPECTED OVER
THE EASTERN GULF OF MEXICO. THIS SYSTEM IS CURRENTLY ANTICIPATED TO MOVE SLOWLY
NORTHWESTWARD THEN DRIFT NORTH/NORTHEASTWARD TOWARDS THE EASTERN GULF COAST AND
THE SOUTHEAST STATES. UPPER-LEVEL LOW PRESSURE IS ANTICIPATED OVER PARTS OF THE
SOUTHERN PLAINS AUG 29-30. UPPER-LEVEL HIGH PRESSURE IS PREDICTED OVER THE
WEST-CENTRAL U.S. FOR MUCH OF THE ASSESSMENT PERIOD. SURFACE LOW PRESSURE NEAR
THE ALASKA PANHANDLE EARLY IN THE PERIOD IS FORECAST TO BRING UNSETTLED WEATHER
TO THE REGION, WHILE LATER IN THE PERIOD SURFACE LOW PRESSURE IS EXPECTED OVER
THE ALEUTIANS. DURING WEEK-2, UPPER-LEVEL LOW PRESSURE IS ANTICIPATED OVER THE
WESTERN U.S. WHILE UPPER-LEVEL HIGH PRESSURE IS EXPECTED OVER THE CENTRAL PART
OF THE NATION.

HAZARDS

HEAVY RAIN FOR PARTS OF THE TENNESSEE VALLEY, SOUTHEAST AND MID-ATLANTIC,
MON-FRI, AUG 29-SEP 2.

HEAVY RAIN FOR PARTS OF SOUTHERN TEXAS, MON-TUE, AUG 29-AUG 30.

MUCH ABOVE NORMAL TEMPERATURES FOR PARTS OF THE NORTHERN ROCKIES AND NORTHERN
PLAINS, MON-TUE, AUG 29-30.

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

SLIGHT CHANCE OF MUCH ABOVE NORMAL TEMPERATURES FOR PARTS OF THE NORTHERN AND
CENTRAL PLAINS, UPPER AND MIDDLE MISSISSIPPI VALLEY, AND GREAT LAKES, SAT-SUN,
SEP 3-4.

MODERATE CHANCE OF MUCH ABOVE NORMAL TEMPERATURES FOR PARTS OF THE NORTHERN AND
CENTRAL PLAINS, AND UPPER MISSISSIPPI VALLEY, SAT, SEP 3.

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

DETAILED SUMMARY

FOR MONDAY AUGUST 29 - FRIDAY SEPTEMBER 02: EARLY IN THE PERIOD, A TROPICAL
DISTURBANCE IS FORECAST OVER THE EASTERN GULF OF MEXICO. THE DISTURBANCE IS
EXPECTED TO DRIFT NORTHWESTWARD THEN NORTH/NORTHEASTWARD TOWARDS THE EASTERN
GULF COAST BY SEP, 1, AND OVER THE SOUTHEAST SEP 2. THIS LEADS TO EXPECTED
HEAVY RAIN (IN EXCESS OF 1 INCH IN 24 HOURS) FOR PARTS OF THE TENNESSEE VALLEY,
SOUTHEAST AND MID-ATLANTIC AUG 29-SEP 2. THE EXACT TRACK AND STRENGTH OF THE
TROPICAL DISTURBANCE ARE HIGHLY UNCERTAIN AT THIS TIME AND ADDITIONAL IMPACTS
(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, ALTHOUGH THE HEAVIEST
RAIN IS CURRENTLY EXPECTED TO FALL TO THE EAST OF WHERE THE MOST SERIOUS
FLOODING IS OCCURRING. PLEASE CONSULT THE LATEST ADVISORIES FROM THE NATIONAL
HURRICANE CENTER AT HTTP://WWW.NHC.NOAA.GOV/.



A MID-LEVEL TROUGH IS FORECAST TO MOVE WESTWARD ACROSS SOUTHERN TEXAS. THIS
LEADS TO ANTICIPATED HEAVY RAIN (IN EXCESS OF 1 INCH IN 24 HOURS) FOR PARTS OF
SOUTHERN TEXAS AUG 29-30.



AN AMPLIFIED RIDGE OVER THE INTERIOR WESTERN CONUS LEADS TO A FORECAST FOR MUCH
ABOVE NORMAL TEMPERATURES (POSITIVE ANOMALIES OF 10-12 DEGREES F) FOR PARTS OF
THE NORTHERN ROCKIES AND NORTHERN PLAINS AUG 29-30.



MONSOONAL FLOW IS EXPECTED TO CAUSE LOCALLY HEAVY RAIN FOR PARTS OF THE
SOUTHWESTERN CONUS.



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



A TROPICAL SYSTEM EXPECTED TO DEVELOP OVER THE EASTERN PACIFIC MAY APPROACH
HAWAII LATE IN THIS PERIOD OR EARLY IN THE WEEK-2 PERIOD. PLEASE CONSULT THE
LATEST ADVISORIES FROM NHC AT HTTP://WWW.NHC.NOAA.GOV/ AND THE CENTRAL PACIFIC
HURRICANE CENTER AT HTTP://WWW.PRH.NOAA.GOV/CPHC/.

FOR SATURDAY SEPTEMBER 03 - FRIDAY SEPTEMBER 09: DURING WEEK-2 THE CIRCULATION
PATTERN IS EXPECTED TO FEATURE A TROUGH OVER THE WESTERN CONUS, A WEAK RIDGE
OVER THE CENTRAL STATES, AND A WEAK TROUGH JUST OFF THE MID-ATLANTIC COAST.
THIS CIRCULATION PATTERN FAVORS BELOW NORMAL TEMPERATURES OVER THE WESTERN
CONUS. ANOMALOUS SOUTHERLY FLOW LEADS TO A SLIGHT RISK OF MUCH ABOVE NORMAL
TEMPERATURES FOR PARTS OF THE NORTHERN AND CENTRAL PLAINS, UPPER AND MIDDLE
MISSISSIPPI VALLEY, AND GREAT LAKES SEP 3-4 AND A MODERATE RISK OF MUCH ABOVE
NORMAL TEMPERATURES FOR PARTS OF THE NORTHERN AND CENTRAL PLAINS, AND UPPER
MISSISSIPPI VALLEY SEP 3.



THE TROPICAL DISTURBANCE CURRENTLY NORTHEAST OF CUBA OF HAITI MAY BE IMPACTING
PARTS OF THE SOUTHEAST AND MID-ATLANTIC EARLY IN THE PERIOD BUT MODEL
UNCERTAINTY PRECLUDES THE SPECIFICATION OF HAZARD SHAPES AT THE CURRENT TIME.
THE ATLANTIC IS SHOWING INCREASED TROPICAL ACTIVITY AND THIS EVOLUTION WILL
NEED TO BE MONITORED. 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 SLIGHTLY TO 7.41 PERCENT FROM 7.71 PERCENT. IMPROVEMENTS WERE
REALIZED ACROSS CENTRAL TEXAS AND THE TENNESSEE VALLEY.

FORECASTER: RANDY SCHECHTER

$$




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