Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4
167
FXUS21 KWNC 301926
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 30 2016

SYNOPSIS: AT THE OUTSET OF THE FORECAST PERIOD MID-LEVEL LOW PRESSURE IS
EXPECTED ACROSS THE PACIFIC NORTHWEST AND NEW ENGLAND, WITH MID-LEVEL HIGH
PRESSURE ACROSS THE NORTHERN PLAINS.  IMPACTS FROM TROPICAL DEPRESSION 9 MAY
CONTINUE TO BE FELT FOR THE NORTHERN PORTION OF THE FLORIDA PENINSULA AND
COASTAL PORTIONS OF THE SOUTHEAST AT THE OUTSET OF THE FORECAST PERIOD.  A COLD
FRONT IS FORECAST TO PUSH EASTWARD FROM THE NORTHERN ROCKIES THROUGH THE
NORTHERN PLAINS DURING WEEK-1.  WEEK-2 IS FORECAST TO GENERALLY FEATURE
MID-LEVEL LOW PRESSURE ACROSS THE NORTHWESTERN CONUS WITH MID-LEVEL HIGH
PRESSURE ACROSS THE GREAT LAKES AND NEW ENGLAND.  A TROPICAL DISTURBANCE
CURRENTLY EXITING THE AFRICAN COAST MAY INFLUENCE THE EASTERN SEABOARD DURING
THE MIDDLE TO END OF WEEK-2.  HAWAII WILL POTENTIALLY BE IMPACTED BY HURRICANE
LESTER EARLY IN WEEK-1.  SURFACE LOW PRESSURE SYSTEMS ARE EXPECTED TO AFFECT
WESTERN AND SOUTHERN ALASKA THROUGHOUT THE FORECAST PERIOD.

HAZARDS

HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST AND THE MID-ATLANTIC, FRI, SEP 2.

FLOODING POSSIBLE ACROSS PORTIONS OF THE SOUTHEAST AND THE LOWER MISSISSIPPI
VALLEY.

HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL PLAINS, THE MIDDLE MISSISSIPPI
VALLEY, THE GREAT LAKES, THE UPPER MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS,
SUN-MON, SEP 4-SEP 5.

HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL PLAINS, THE MIDDLE MISSISSIPPI
VALLEY, THE GREAT LAKES, AND THE UPPER MISSISSIPPI VALLEY, TUE, SEP 6.

MUCH ABOVE NORMAL TEMPERATURES ACROSS PORTIONS OF THE NORTHERN PLAINS, FRI, SEP
2.

MUCH ABOVE NORMAL TEMPERATURES ACROSS PORTIONS OF THE GREAT LAKES, THE
MID-ATLANTIC, THE NORTHEAST, AND THE CENTRAL APPALACHIANS, TUE, SEP 6.

SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PORTIONS OF THE CENTRAL
PLAINS, THE CENTRAL GREAT BASIN, THE NORTHERN PLAINS, THE NORTHERN ROCKIES, THE
CENTRAL ROCKIES, AND THE NORTHERN GREAT BASIN, WED-FRI, SEP 7-SEP 9.

MODERATE RISK OF MUCH ABOVE-NORMAL TEMPERATURES FOR PORTIONS OF THE NORTHEAST,
WED-THU, SEP 7-SEP 8.

SLIGHT RISK OF MUCH ABOVE-NORMAL TEMPERATURES FOR PORTIONS OF THE GREAT LAKES,
THE MID-ATLANTIC, THE NORTHEAST, THE CENTRAL APPALACHIANS, AND THE OHIO VALLEY,
WED-SAT, SEP 7-SEP 10.

SEVERE DROUGHT ACROSS THE CENTRAL PLAINS, THE MID-ATLANTIC, THE LOWER
MISSISSIPPI VALLEY, THE CENTRAL GREAT BASIN, THE NORTHERN PLAINS, THE TENNESSEE
VALLEY, THE GREAT LAKES, THE SOUTHERN APPALACHIANS, HAWAII, THE NORTHERN
ROCKIES, THE NORTHEAST, CALIFORNIA, THE NORTHERN GREAT BASIN, THE SOUTHEAST,
THE CENTRAL APPALACHIANS, THE SOUTHERN PLAINS, AND THE SOUTHWEST.

DETAILED SUMMARY

FOR FRIDAY SEPTEMBER 02 - TUESDAY SEPTEMBER 06: AS THE FORECAST PERIOD BEGINS,
TROPICAL DEPRESSION 9 IS FORECAST TO HAVE CROSSED FLORIDA AND EMERGED BACK INTO
THE ATLANTIC OCEAN.  HEAVY RAINS (EXCEEDING 1" IN 24 HOURS) MAY LINGER OVER
COASTAL PORTIONS OF THE SOUTHEAST AND THE NORTHERN PORTION OF THE FLORIDA
PENINSULA ON SEPTEMBER 2.  BY THIS POINT IN TIME, IT IS ANTICIPATED THAT ANY
POTENTIAL HAZARDOUS WINDS OR EMBEDDED SEVERE WEATHER WITH THE SYSTEM WILL BE
OFFSHORE.  FLOODING IS POSSIBLE ACROSS PORTIONS OF FLORIDA DUE TO THE HEAVY
RAINS ASSOCIATED WITH TROPICAL DEPRESSION 9.  IT IS NOTED THAT THE 12Z GFS,
UKMET, AND CMC MODELS ALL FORECAST TROPICAL DEPRESSION 9 TO MAKE A SLIGHT LEFT
TURN BACK TOWARDS THE NORTHEAST TO VARYING DEGREES, WHILE 12Z EUROPEAN GUIDANCE
WAS UNAVAILABLE AT THE TIME OF THE FORECAST.  THE CURRENT FORECAST ASSOCIATED
WITH TROPICAL DEPRESSION 9 IS MAINTAINED IN LINE WITH THE NATIONAL HURRICANE
CENTER (NHC) GUIDANCE WHICH HAS BEEN MORE CLOSELY ALIGNED WITH THE EUROPEAN
MODEL OUTPUT.



ANOMALOUS 500-HPA RIDGING AT THE START OF THE FORECAST PERIOD BRINGS A CHANCE
FOR MUCH ABOVE NORMAL TEMPERATURES TO PORTIONS OF THE NORTHERN PLAINS ON
SEPTEMBER 2.  HERE MAXIMUM TEMPERATURES COULD EXCEED 12-16 DEGREES F ABOVE
NORMAL.  THIS WARMTH IS EXPECTED TO BE ENHANCED VIA SOUTHERLY FLOW AHEAD OF A
COLD FRONT FORECAST TO PUSH ACROSS THE NORTHERN TIER OF THE U.S. DURING WEEK-1.
 WITH THIS FRONT AND HEAVY RAIN THREAT IS FORECAST FOR SEPTEMBER 4-5 TO SHIFT
SOUTHWARD AND EASTWARD FROM THE UPPER MISSISSIPPI VALLEY THROUGH THE MIDWEST
AND CENTRAL PLAINS BY SEPTEMBER 6.  SOME EMBEDDED SEVERE WEATHER MAY EXIST
WITHIN THIS HIGHLIGHTED REGION, ALTHOUGH CONFIDENCE IS NOT HIGH ENOUGH TO
SPECIFY AN AREA AT THIS TIME.



A SECOND REGION OF MUCH ABOVE-NORMAL TEMPERATURES IS FORECAST ACROSS INTERIOR
PORTIONS OF THE MID-ATLANTIC AND NEW ENGLAND FOR SEPTEMBER 6 WHERE MAXIMUM
TEMPERATURES COULD EXCEED 12 DEGREES F ABOVE NORMAL.  THIS WARMTH MAY LINGER
INTO THE EARLY PORTION OF WEEK-2 ACROSS THE NORTHEAST.



ELSEWHERE, MARGINAL ENHANCEMENT OF FIRE WEATHER CONDITIONS ARE FORECAST FOR
PORTIONS OF THE GREAT BASIN AND NORTHERN AND CENTRAL ROCKIES ON SEPTEMBER 2.
BREEZY, DRY, AND WARM CONDITIONS ARE EXPECTED ALONG WITH THE PRESENCE OF DRY
FUELS, ALTHOUGH NOT SUFFICIENTLY ENOUGH TO WARRANT A HAZARD ON THE MAP.



HURRICANE LESTER IS FORECAST TO PASS NORTH OF THE HAWAIIAN ISLANDS ON SEPTEMBER
2-3.  ASSOCIATED HIGH WINDS AND HEAVY RAINS ARE POSSIBLE WITH ITS PASSAGE.
FORECAST GUIDANCE GENERALLY PREDICTS THE SYSTEM TO BE A WEAK HURRICANE OR
STRONG TROPICAL STORM AT THE TIME OF ITS CLOSEST APPROACH TO HAWAII.  FOR MORE
INFORMATION ON LESTER PLEASE VISIT THE NHC AT HTTP://WWW.NHC.NOAA.GOV OR
CENTRAL PACIFIC HURRICANE CENTER AT HTTP://WWW.PRH.NOAA.GOV/CPHC/



SURFACE LOW PRESSURE IS FORECAST ACROSS THE BERING SEA FOR MUCH OF WEEK-1, AND
IS EXPECTED TO BRING RAINS BELOW HAZARDOUS CRITERIA TO WESTERN AND SOUTHERN
PORTIONS OF THE STATE.  RAINFALL AMOUNTS IN THE VICINITY OF THE KENAI PENINSULA
ON SEPTEMBER 4 MAY APPROACH HAZARDS CRITERIA, HOWEVER DYNAMICAL MODEL
INCONSISTENCY REGARDING THE TIMING AND COVERAGE OF THIS PRECIPITATION PRECLUDES
A HAZARD FROM BEING IDENTIFIABLE AT PRESENT.

FOR WEDNESDAY SEPTEMBER 07 - TUESDAY SEPTEMBER 13: DURING WEEK-2, ANOMALOUS
500-HPA RIDGING IS GENERALLY FAVORED ACROSS THE NORTHEAST WITH ANOMALOUS
TROUGHING ACROSS THE NORTHERN ROCKIES.  THE AREA IMPACTED BY THIS RIDGE IS
FAVORED FOR MUCH ABOVE-NORMAL TEMPERATURES EARLY IN WEEK-2.  THE GEFS
PROBABILISTIC EXTREMES TOOL INDICATES A BROAD REGION ACROSS THE MID-ATLANTIC
AND NORTHEAST WITH AT LEAST A 20% CHANCE OF EXCEEDING THE 85TH PERCENTILE OF
CLIMATOLOGICAL MAXIMUM TEMPERATURES YIELDING A SLIGHT RISK OF MUCH ABOVE-NORMAL
TEMPERATURES FOR SEPTEMBER 7-10.  AN EMBEDDED MODERATE RISK OF MUCH
ABOVE-NORMAL TEMPERATURES FOR SEPTEMBER 7-8 IS FORECAST FOR NEW ENGLAND AND
PORTIONS OF THE MID-ATLANTIC WHERE THE TOOL IDENTIFIES A 40% CHANCE OF
EXCEEDING THE 85TH PERCENTILE OF CLIMATOLOGICAL MAXIMUM TEMPERATURES.



WITH TROUGHING FAVORED OUT WEST, A SLIGHT RISK OF MUCH BELOW-NORMAL
TEMPERATURES IS FORECAST FOR SEPTEMBER 7-9 ACROSS PORTIONS OF THE NORTHERN AND
CENTRAL ROCKIES, GREAT BASIN, AND NORTHERN INTERMOUNTAIN REGIONS.  HERE THE
GEFS INDICATES A BETTER THAN 20% CHANCE OF THIS AREA EXPERIENCING MINIMUM
TEMPERATURES BELOW THE 15TH CLIMATOLOGICAL PERCENTILE VALUE.  THE HIGHLIGHTED
AREA ALSO FOCUSES ON LOCATIONS THAT COULD SEE MINIMUM TEMPERATURES DIP BELOW 40
DEGREES F.



THE EASTERLY WAVE EXITING THE AFRICAN COAST NEAR THE TIME OF THIS FORECAST
BEING MADE (AL92L) BEARS MONITORING FOR U.S. IMPACTS DURING THE MIDDLE TO END
OF WEEK-2.  GEFS GUIDANCE HAS SUPPORTED A TRACK FOR THIS SYSTEM OF JUST NORTH
OF THE GREATER ANTILLES IN WEEK-2 FOR THE PAST FEW DAYS.  TODAY`S 0Z
OPERATIONAL ECMWF GUIDANCE SIMILARLY DEPICTS A DISTURBANCE IN ITS LAST FRAME
JUST NORTH OF THE BAHAMAS AT 0Z ON SEPTEMBER 9.  THE 0Z GEFS HINTED AT THIS
SYSTEM APPROACHING THE SOUTHEASTERN COASTLINE FOR SEPTEMBER 9-11, WHILE THE 12Z
GEFS GENERALLY SHOWS THE SYSTEM RECURVING EARLIER AND POTENTIALLY LIMITING U.S.
IMPACTS, DESPITE SOME MEMBERS BRINGING THE DISTURBANCE INTO THE GULF OF MEXICO.
 AS WITH YESTERDAY, STRONG CONSIDERATION WAS GIVEN TO A HEAVY RAINFALL HAZARD
WITH THIS SYSTEM, BUT GIVEN PREDICTABILITY LIMITATIONS AND THE SUBSTANTIAL
FORECAST LEAD TIME, NO RELATED HAZARD IS FORECAST.  THE NHC CURRENTLY GIVES
AL92L A 40% CHANCE OF UNDERGOING TROPICAL CYCLOGENESIS OVER THE NEXT 5 DAYS AS
OF 2 PM EDT ON AUGUST 30, AND INTERESTED PARTIES ARE REFERRED TO THE NHC FOR
FURTHER INFORMATION.



ACCORDING TO THE U.S. DROUGHT MONITOR ISSUED ON AUGUST 25, 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: DANIEL HARNOS

$$




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.