Prognostic Meteorological Discussion
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1
000
FXUS21 KWNC 311922
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 31 2016

SYNOPSIS: AS THE FORECAST PERIOD BEGINS, MID-LEVEL HIGH PRESSURE IS EXPECTED
ACROSS THE GREAT LAKES WITH MID-LEVEL LOW PRESSURE OVER THE PACIFIC NORTHWEST.
WHAT IS PRESENTLY TROPICAL STORM HERMINE IS ANTICIPATED TO BE ALONG THE EASTERN
SEABOARD EARLY IN THE FORECAST PERIOD.  A COLD FRONT IS FORECAST TO BECOME
STATIONARY OVER FLORIDA EARLY IN WEEK-1.  A SLOW MOVING COLD FRONT IS FORECAST
TO PUSH EASTWARD THROUGH THE NORTHERN PLAINS THROUGH THE WESTERN GREAT LAKES
THROUGHOUT WEEK-1.  DURING WEEK-2, EXPECTATIONS ARE FOR THE MID-LEVEL PATTERN
TO GENERALLY CONTINUE, WHILE A TROPICAL DISTURBANCE MAY APPROACH THE SOUTHEAST.
 HURRICANE LESTER IS FORECAST TO PASS NORTH OF HAWAII DURING WEEK-1.  WESTERN
AND SOUTHERN ALASKA ARE EXPECTED TO BE AFFECTED BY PERIODIC SURFACE LOW
PRESSURE SYSTEMS DURING WEEK-1 AND 2.

HAZARDS

HEAVY RAIN ACROSS PORTIONS OF THE MID-ATLANTIC, SAT, SEP 3.

HEAVY RAIN ACROSS PORTIONS OF THE MID-ATLANTIC AND THE NORTHEAST, SUN, SEP 4.

HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL PLAINS, THE SOUTHEAST, THE UPPER
MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS, SAT-SUN, SEP 3-SEP 4.

HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL PLAINS, THE MIDDLE MISSISSIPPI
VALLEY, THE GREAT LAKES, THE UPPER MISSISSIPPI VALLEY, AND THE NORTHERN PLAINS,
MON-TUE, SEP 5-SEP 6.

HEAVY RAIN ACROSS PORTIONS OF THE MIDDLE MISSISSIPPI VALLEY, THE GREAT LAKES,
AND THE UPPER MISSISSIPPI VALLEY, WED, SEP 7.

FLOODING POSSIBLE ACROSS PORTIONS OF THE SOUTHEAST.

FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY.

HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST, THE MID-ATLANTIC, AND THE LOWER
MISSISSIPPI VALLEY, THU-SUN, SEP 8-SEP 11.

HIGH WINDS ACROSS PORTIONS OF THE MID-ATLANTIC, SAT, SEP 3.

MUCH ABOVE NORMAL TEMPERATURES ACROSS PORTIONS OF THE GREAT LAKES, THE
MID-ATLANTIC, THE NORTHEAST, THE CENTRAL APPALACHIANS, AND THE OHIO VALLEY,
TUE-WED, SEP 6-SEP 7.

SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PORTIONS OF THE CENTRAL
PLAINS, THE CENTRAL ROCKIES, THE CENTRAL GREAT BASIN, THE NORTHERN PLAINS, THE
NORTHERN ROCKIES, THE SOUTHERN ROCKIES, THE NORTHERN GREAT BASIN, AND THE
SOUTHWEST, THU-SAT, SEP 8-SEP 10.

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,
THU-SUN, SEP 8-SEP 11.

MODERATE RISK OF MUCH ABOVE-NORMAL TEMPERATURES FOR PORTIONS OF THE NORTHEAST
AND THE GREAT LAKES, THU-FRI, SEP 8-SEP 9.

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 SATURDAY SEPTEMBER 03 - WEDNESDAY SEPTEMBER 07: AS THE FORECAST PERIOD
BEGINS, WHAT IS PRESENTLY TROPICAL STORM HERMINE IS EXPECTED TO BE IN THE
VICINITY OF THE MID-ATLANTIC.  THE NATIONAL HURRICANE CENTER (NHC) HAS SHIFTED
THEIR 5-DAY FORECAST TRACK WESTWARD RELATIVE TO YESTERDAY, SUCH THAT LONG
ISLAND AND SOUTHERN NEW ENGLAND NOW LIE WITHIN THE CONE OF UNCERTAINTY AS OF 2
PM EDT ON AUGUST 31.  WHILE THE NHC HAS SHIFTED THEIR FORECAST TRACK WESTWARD,
12Z DYNAMICAL MODEL GUIDANCE IS GENERALLY EVEN FURTHER WEST, RESULTING IN A
HEAVY RAIN HAZARD (EXCEEDING 1" IN 24 HOURS) FORECAST ACROSS PORTIONS OF THE
MID-ATLANTIC FOR SEPTEMBER 3.  ON SEPTEMBER 4, THE HEAVY RAIN HAZARD IS
EXPECTED TO SHIFT NORTHWARD COVERING DOWNSTATE NEW YORK AND SOUTHERN NEW
ENGLAND.  BOTH OF THESE REGIONS ARE HIGHLIGHTED IN LINE WITH THE 12Z GEFS
OUTPUT.  HIGH WINDS (EXCEEDING 35 MPH) ARE FORECAST ON SEPTEMBER 3 FROM EASTERN
NORTH CAROLINA NORTHWARD THROUGH CENTRAL NEW JERSEY.  12Z DYNAMICAL MODEL
GUIDANCE GENERALLY KEEPS THE STRONGEST WINDS OFFSHORE ON SEPTEMBER 4.  FOR THE
LATEST GUIDANCE ON THIS SYSTEM PLEASE REFERENCE YOUR LOCAL NATIONAL WEATHER
SERVICE OFFICE OR THE NHC AT HTTP://WWW.NHC.NOAA.GOV.



FURTHER SOUTH, A STATIONARY BOUNDARY IS FORECAST TO BE DRAPED ACROSS FLORIDA ON
SEPTEMBER 3-4.  A RICH PLUME OF MOISTURE OFF THE GULF OF MEXICO ASSOCIATED WITH
THIS FEATURE IS EXPECTED TO SUPPORT A HEAVY RAIN HAZARD FOR THE AFOREMENTIONED
DATES ACROSS ROUGHLY THE NORTHERN THIRD OF THE FLORIDA PENINSULA.  ANTECEDENT
RAINFALL FROM TROPICAL DEPRESSION 9 COULD YIELD POSSIBLE FLOODING IN THE
VICINITY OF TAMPA BAY THAT MAY BE EXACERBATED BY RAINS WITH THIS STALLED
BOUNDARY.



AHEAD OF THE MID-LEVEL TROUGH EXPECTED TO BE SLOWLY PROGRESSING ACROSS THE
WEST, HEAVY RAINS ARE FORECAST.  THE HEAVY RAIN THREAT IS EXPECTED TO SHIFT
EASTWARD FROM THE NORTHERN AND CENTRAL PLAINS ON SEPTEMBER 3-4, TO THE UPPER
MISSISSIPPI VALLEY ON SEPTEMBER 5-6, AND THE WESTERN GREAT LAKES ON SEPTEMBER
7.  SEVERE WEATHER CHANCES COULD BE ELEVATED WITH THE PASSAGE OF THIS SYSTEM,
BUT MODEL UNCERTAINTY LIMITS THE INTRODUCTION OF A HAZARD ON THE MAP.



FURTHER WEST, A MARGINALLY ELEVATED FIRE WEATHER RISK EXISTS FOR SEPTEMBER 3-4
ACROSS PORTIONS OF THE GREAT BASIN, NORTHERN AND CENTRAL ROCKIES, AND NORTHERN
INTERMOUNTAIN REGION.  ALTHOUGH NOT HIGHLIGHTED ON THE MAP, DRY FUELS ARE
EXPECTED TO BE PRESENT IN CONJUNCTION WITH BREEZY AND DRY CONDITIONS.



THE NHC FORECAST BRINGS HURRICANE LESTER JUST NORTH OF THE HAWAIIAN ISLANDS ON
SEPTEMBER 4.  HIGH WINDS AND HEAVY RAINS ARE POSSIBLE WITH THE SYSTEM`S
PASSAGE.  FOR MORE INFORMATION, INTERESTED PARTIES ARE REFERRED TO THEIR LOCAL
FORECAST OFFICE, THE NHC, OR CENTRAL PACIFIC HURRICANE CENTER AT
HTTP://WWW.PRH.NOAA.GOV/CPHC/.



A SURFACE LOW IS FORECAST TO SHIFT FROM THE BERING SEA INTO THE WESTERN ALASKA
COASTLINE DURING WEEK-1.  LATE IN THE WEEK, PERSISTENT ONSHORE FLOW IS FAVORED
ACROSS SOUTHEASTERN ALASKA AND THE ALASKAN PANHANDLE THAT COULD BRING RAINS
THAT APPROACH HAZARDOUS CRITERIA.  ENSEMBLE GUIDANCE HAS BEEN INCONSISTENT IN
THE TIMING AND LOCATION OF THIS PRECIPITATION, AND THUS NO HAZARD IS ISOLATED
ON THE FORECAST MAP.

FOR THURSDAY SEPTEMBER 08 - WEDNESDAY SEPTEMBER 14: DURING WEEK-2, POSITIVE
500-HPA HEIGHT ANOMALIES ARE FAVORED OVER THE GREAT LAKES AND NORTHEAST WITH
TROUGHING INITIALLY ANTICIPATED THROUGH THE NORTHERN ROCKIES.  ENSEMBLE
GUIDANCE SUGGESTS THE FLOW TO DEAMPLIFY OVER THE COURSE OF WEEK-2, WITH A
GENERAL TENDENCY FOR WEAK RIDGING THROUGHOUT THE NORTHERN CONUS.



WITH THE POSITIVE 500-HPA HEIGHT ANOMALIES FORECAST FOR THE NORTHEASTERN CONUS,
ELEVATED CHANCES OF MUCH ABOVE-NORMAL TEMPERATURES ARE FORECAST.  A SLIGHT RISK
OF MUCH ABOVE-NORMAL TEMPERATURES IS FORECAST FOR SEPTEMBER 8-11 FOR PORTIONS
OF THE EASTERN GREAT LAKES, MID-ATLANTIC, AND NORTHEAST.  WITHIN THIS AREA, A
MODERATE RISK OF MUCH ABOVE NORMAL TEMPERATURES IS POSSIBLE FOR UPSTATE NEW
YORK AND NORTHERN NEW ENGLAND ON SEPTEMBER 8-9 WHEN THE FORECAST 500-HPA HEIGHT
ANOMALIES ARE EXPECTED TO BE STRONGEST.  FURTHER WEST, WITH 500-HPA TROUGHING
FAVORED EARLY IN THE WEEK A SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES IS
FORECAST FOR SEPTEMBER 8-10 CENTERED ON THE CENTRAL ROCKIES AND GREAT BASIN.



THE NHC CONTINUES TO MONITOR AN EASTERLY WAVE THAT PASSED CAPE VERDE IN THE
PAST 24 HOURS, CURRENTLY GIVING THIS SYSTEM A 30% CHANCE OF DEVELOPING OVER THE
NEXT 5 DAYS AS IT IS FORECAST TO APPROACH THE LESSER ANTILLES (AS OF 2 PM EDT
ON AUGUST 31).  THIS DISTURBANCE IS TIED INTO A DEEP PLUME OF MOISTURE
EXTENDING OFF THE INTERTROPICAL CONVERGENCE ZONE.  ENSEMBLE AND OPERATIONAL
DYNAMICAL MODEL GUIDANCE HAS GENERALLY BEEN CONSISTENT FOR MULTIPLE RUNS WITH
HAVING THIS SYSTEM APPROACH THE SOUTHEAST DURING WEEK-2.  WHILE NO PREDICTION
IS MADE HERE REGARDING THE DISTURBANCE`S INTENSITY AS IT POTENTIALLY APPROACHES
THE U.S., THE DEEP MOISTURE THE SYSTEM IS EXPECTED TO BE EMBEDDED WITHIN WOULD
PROVIDE FOR ACCOMPANYING HEAVY RAINS IN THE VICINITY OF ITS TRACK.  GIVEN THE
DIVERGING MODEL SOLUTIONS IN BOTH TIME AND SPACE, A BROAD REGION OF HEAVY RAIN
IS FORECAST EXTENDING FROM LOUISIANA THROUGH THE OUTER BANKS FOR SEPTEMBER
8-11.  THIS SYSTEM WILL CONTINUE TO BE MONITORED IN AN EFFORT TO NARROW DOWN
THE POTENTIALLY IMPACTED AREAS AND TIME FRAME.



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.