Prognostic Meteorological Discussion
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FXUS21 KWNC 271754
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JULY 27 2016

SYNOPSIS: AS THE FORECAST PERIOD BEGINS, A STATIONARY FRONT IS ANTICIPATED TO
EXTENDEAST FROM THE CENTRAL PLAINS THROUGH THE MID-ATLANTIC.  EXPECTATIONS ARE
FOR THIS BOUNDARY TO SLOWLY DROP SOUTHWARD THROUGHOUT WEEK-1.  MID-LEVEL HIGH
PRESSURE IS FORECAST TO DOMINATE THE WEST DURING WEEK-1.  THIS HIGH IS FORECAST
TO SHIFT EAST TO THE CENTRAL CONUS AND WEAKEN DURING WEEK-2.  A COLD FRONT IS
FORECAST TO PUSH SOUTH AND EAST ACROSS ALASKA EARLY IN WEEK-1, WITH ANOTHER
COLD FRONT POTENTIALLY IMPACTING NORTHERN ALASKA LATER IN WEEK-1.  MID-LEVEL
HIGH PRESSURE IS FORECAST TO BUILD ACROSS ALASKA DURING WEEK-2.

HAZARDS

MUCH ABOVE-NORMAL TEMPERATURES ACROSS PORTIONS OF THE CENTRAL GREAT BASIN, THE
NORTHERN PLAINS, THE NORTHERN ROCKIES, CALIFORNIA, THE NORTHERN GREAT BASIN,
AND THE SOUTHWEST, SAT, JUL 30.

HIGH WINDS ACROSS PORTIONS OF THE NORTH SLOPE OF ALASKA, MON-TUE, AUG 1-AUG 2.

HEAVY RAIN ACROSS PORTIONS OF INTERIOR ALASKA, SAT-SUN, JUL 30-JUL 31.

HEAVY RAIN ACROSS PORTIONS OF THE SOUTHEAST AND THE MID-ATLANTIC, SUN-TUE, JUL
31-AUG 2.

MODERATE RISK OF MUCH ABOVE-NORMAL TEMPERATURES FOR PORTIONS OF THE GREAT
LAKES, THU, AUG 4.

SLIGHT RISK OF MUCH ABOVE-NORMAL TEMPERATURES FOR PORTIONS OF THE NORTHEAST,
THE CENTRAL APPALACHIANS, THE MIDDLE MISSISSIPPI VALLEY, THE MID-ATLANTIC, THE
GREAT LAKES, AND THE OHIO VALLEY, THU-SAT, AUG 4-AUG 6.

SLIGHT RISK OF MUCH ABOVE-NORMAL TEMPERATURES FOR PORTIONS OF THE LOWER
MISSISSIPPI VALLEY, THE TENNESSEE VALLEY, THE MID-ATLANTIC, THE SOUTHERN
APPALACHIANS, THE SOUTHEAST, AND THE SOUTHERN PLAINS, THU-TUE, AUG 4-AUG 9.

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

DETAILED SUMMARY

FOR SATURDAY JULY 30 - WEDNESDAY AUGUST 03: ACROSS THE WEST, MUCH ABOVE-NORMAL
TEMPERATURES ARE EXPECTED FOR JULY 30, ASSOCIATED WITH 500-HPA RIDGING DESPITE
MODEST FORECAST HEIGHT ANOMALIES.  MAXIMUM TEMPERATURES COULD EXCEED 8-12
DEGREES F ABOVE-NORMAL HERE IN ADVANCE OF A WEAK COLD FRONT FORECAST TO DESCEND
FROM CANADA.  ELSEWHERE ACROSS THE WEST, MARGINAL CHANCES FOR DRY THUNDERSTORMS
ARE INDICATED BY THE STORM PREDICTION CENTER (SPC) FOR PORTIONS OF THE GREAT
BASIN ON JULY 30-31.  THE SPC IS ALSO ANTICIPATING MARGINAL FIRE WEATHER
CONDITIONS  JULY 30-AUGUST 1 ACROSS THE GREAT BASIN AND NORTHERN INTERMOUNTAIN
REGIONS TIED TO DRY LOW-LEVEL CONDITIONS, WARM TEMPERATURES, AND LOCALLY WINDY
AREAS COMBINED WITH THE PRESENCE OF DRY FUELS.  GIVEN THAT THE TWO
AFOREMENTIONED FIRE HAZARDS ARE PERCEIVED AS MARGINAL AT PRESENT, NO HAZARD IS
DEPICTED ON THE FORECAST MAP.



HEAVY RAINFALL (EXCEEDING 1" IN 24 HOURS) IS FORECAST FOR EASTERN PORTIONS OF
THE MID-ATLANTIC JULY 31-AUGUST 2 ASSOCIATED WITH A COLD FRONT SLOWLY PUSHING
SOUTH THROUGH THE REGION.  THE HEAVY RAIN THREAT SHOULD SHIFT SOUTHWARD ACROSS
THE AFOREMENTIONED REGION THROUGHOUT THE INDICATED PERIOD.



HEAVY RAINFALL IS ALSO FORECAST ACROSS PORTIONS OF WESTERN AND INTERIOR ALASKA
ON JULY 30-31 ASSOCIATED WITH A COLD FRONT EXPECTED TO BE PUSHING SOUTHEAST
ACROSS THE STATE.  WHILE RAINS FORECAST HERE MAY NOT MEET ALASKA`S HAZARDOUS
RAINFALL CRITERIA, ANTECEDENT WET CONDITIONS COULD YIELD FLOODING CONCERNS
RESULTING IN A HAZARD DEPICTION.  ANOTHER COLD FRONT IS FORECAST TO PUSH SOUTH
ACROSS THE NORTH SLOPE LATE IN WEEK-1, HOWEVER MODEL GUIDANCE SUGGESTS
ASSOCIATED RAINFALL TO BE BELOW HAZARDOUS CRITERIA.  HOWEVER, HIGH WINDS
(EXCEEDING 25 KNOTS) ARE FORECAST BEHIND THIS FRONTAL BOUNDARY FOR AUGUST 1-2
THAT COULD LEAD TO COASTAL EROSION AND OTHER HAZARDS.

FOR THURSDAY AUGUST 04 - WEDNESDAY AUGUST 10: AT THE OUTSET OF WEEK-2,
LOW-AMPLITUDE FLOW IS FAVORED ACROSS THE CONUS BY DYNAMICAL MODEL GUIDANCE,
WITH A 591 DM RIDGE FORECAST ACROSS SOUTHERN PLAINS.  POSITIVE 500-HPA HEIGHT
ANOMALIES ARE FORECAST TO BE MOST PRONOUNCED ON AUGUST 4 ACROSS THE GREAT LAKES
BY BOTH THE GEFS AND ECMWF ENSEMBLE GUIDANCE.  HERE THE GEFS PROBABILISTIC
EXTREMES TOOL SUPPORT A 40% CHANCE OF EXCEEDING THE 85TH PERCENTILE OF
CLIMATOLOGICAL MAXIMUM TEMPERATURES FOR PORTIONS OF WESTERN NEW YORK
SURROUNDING LAKE ONTARIO, RESULTING IN A MODERATE RISK OF MUCH ABOVE-NORMAL
TEMPERATURES BEING FORECAST.  A SLIGHT RISK OF MUCH ABOVE-NORMAL TEMPERATURES
IS FORECAST FOR A BROADER REGION EXTENDING FROM THE MIDDLE-MISSISSIPPI VALLEY
THROUGH NEW ENGLAND FOR AUGUST 4-6.  BEYOND THIS POINT TROUGHING IS FORECAST TO
BUILD SOUTHWARD ACROSS NEW ENGLAND BY THE GEFS AND ECMWF ENSEMBLES THROUGH THE
REMAINDER OF WEEK-2.



THE OTHER REGION TARGETED FOR ENHANCED POTENTIAL OF MUCH ABOVE-NORMAL
TEMPERATURES IS PARTS OF THE SOUTHEAST AND SOUTHERN PLAINS FOR AUGUST 4-9.
HERE THE GEFS PROBABILISTIC EXTREMES TOOL GIVES A GREATER THAN 20% CHANCE OF
EXCEEDING THE 85TH PERCENTILE OF CLIMATOLOGICAL MAXIMUM TEMPERATURES DESPITE NO
ROBUST 500-HPA HEIGHT ANOMALIES IN THE ENSEMBLE MEAN.  REFORECAST GUIDANCE FROM
THE GEFS, ECMWF ENSEMBLES, AND NAEFS FOR WEEK-2 ALL HIGHLIGHT THIS REGION AS
THE MOST LIKELY CONUS AREA TO EXPERIENCE ABOVE-NORMAL TEMPERATURES DURING
WEEK-2.



NUMERICAL GUIDANCE SUGGESTS ATLANTIC TROPICAL CYCLONE ACTIVITY MAY INCREASE
OVER THE COMING TWO WEEKS, IN LINE WITH CLIMATOLOGY.  AN AFRICAN EASTERLY WAVE
IS FORECAST TO ENTER THE ATLANTIC PRIOR TO THE FORECAST PERIOD, WITH THE
NATIONAL HURRICANE CENTER (NHC) CURRENTLY GIVING IT A 20% CHANCE OF UNDERGOING
TROPICAL CYCLOGENESIS THROUGH AUGUST 1ST.  GEFS TROPICAL CYCLONE TRACKING
GUIDANCE HINTS AT THE SYSTEM POTENTIALLY DEVELOPING LATE IN WEEK-1 OR DURING
WEEK-2 AND POSSIBLY BEING IN THE VICINITY OF HISPANIOLA BY THE END OF THE
FORECAST PERIOD.  SOME CFS MEMBERS DEVELOP THE SYSTEM, BUT FAVOR A RECURVING
TRACK FOR THE POTENTIAL SYSTEM AROUND THE BASE OF THE SUBTROPICAL RIDGE THROUGH
THE CENTRAL ATLANTIC.  WHILE MAINLAND IMPACTS FROM THIS DISTURBANCE WOULD
LIKELY BE BEYOND THE FORECAST PERIOD, PUERTO RICO COULD BE IMPACTED IF SOME OF
THE GEFS SOLUTIONS WERE TO MATERIALIZE.  INTERESTED PARTIES CAN FIND SUBSEQUENT
GUIDANCE RELATING TO THIS SYSTEM VIA THE GLOBAL TROPICAL HAZARDS OUTLOOK
(HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/PRECIP/CWLINK/GHAZARDS/INDEX.PHP) AND
NHC OUTLOOKS (HTTP://WWW.NHC.NOAA.GOV/).



ACCORDING TO THE U.S. DROUGHT MONITOR (USDM), RELEASED ON JULY 21, SEVERE, OR
GREATER INTENSITY, DROUGHT COVERS 5.68 PERCENT OF THE U.S. DROUGHT MONITOR
AREAS (INCLUDING ALASKA, HAWAII, AND PUERTO RICO), AN INCREASE OF A HALF
PERCENT SINCE THE PREVIOUS WEEK. THIS INCREASE IS DUE TO AN EXPANSION OF
SHORT-TERM SEVERE DROUGHT EAST OF THE ROCKIES.

FORECASTER: DANIEL HARNOS

$$



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