Prognostic Meteorological Discussion
Issued by NWS

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FXUS21 KWNC 281856
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JULY 28 2016

SYNOPSIS: DURING WEEK-1, TWO FRONTAL BOUNDARIES ARE ANTICIPATED TO IMPACT THE
LOWER 48 STATES:  A COLD FRONT DROPPING SOUTH ACROSS THE EASTERN HALF OF THE
COUNTRY AND ANOTHER COLD FRONT PUSHING EASTWARD FROM THE PACIFIC NORTHWEST TO
THE NORTHERN PLAINS.  LOW-LEVEL HIGH PRESSURE IS EXPECTED TO DOMINATE SOUTHERN
PORTIONS OF THE U.S. THROUGHOUT WEEK-1.  FOR WEEK-2 MID-LEVEL LOW PRESSURE IS
EXPECTED BUILD ACROSS THE NORTHEAST WITH MID-LEVEL HIGH PRESSURE IN CONTROL
FURTHER WEST.  TWO COLD FRONTS ARE FORECAST TO INFLUENCE ALASKA DURING WEEK-1,
IMPACTING THE INTERIOR AND NORTHERN PORTIONS OF THE STATE.  DURING WEEK-2
ALASKA IS FAVORED TO EXPERIENCE MID-LEVEL HIGH PRESSURE.

HAZARDS

HEAVY RAIN ACROSS EASTERN PORTIONS OF THE MID-ATLANTIC AND CAROLINAS, SUN-MON,
JUL 31-AUG 1.

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

HIGH WINDS ACROSS PORTIONS OF THE NORTH SLOPE OF ALASKA, SUN-MON, JUL 31-AUG 1.

SLIGHT RISK OF MUCH ABOVE-NORMAL TEMPERATURES FOR PORTIONS OF THE GREAT LAKES,
THE MID-ATLANTIC, AND THE NORTHEAST, FRI, AUG 5.

SLIGHT RISK OF MUCH ABOVE-NORMAL TEMPERATURES FOR PORTIONS OF THE LOWER
MISSISSIPPI VALLEY, THE CAROLINAS, THE SOUTHERN APPALACHIANS, THE SOUTHEAST,
AND THE SOUTHERN PLAINS, FRI-MON, AUG 5-AUG 8.

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

DETAILED SUMMARY

FOR SUNDAY JULY 31 - THURSDAY AUGUST 04: HEAVY RAINFALL (EXCEEDING 1" IN 24
HOURS) IS FORECAST FOR SOUTHEASTERN VIRGINIA AND THE EASTERN CAROLINAS ON JULY
31 AND AUGUST 1 ASSOCIATED WITH A COLD FRONT EXPECTED TO SLOWLY DESCEND THROUGH
THE REGION.  THE REGION OF RAINFALL INDICATED ON THE MAP IS ANTICIPATED TO
SHIFT TOWARDS COASTAL REGIONS FOR THE SECOND DAY OF THE EVENT.



ANOTHER AREA OF HEAVY RAINFALL ASSOCIATED WITH A COLD FRONT IS FORECAST FOR
PORTIONS IMMEDIATELY WEST AND NORTH OF THE ALASKA RANGE ON JULY 31.  ANTECEDENT
WET CONDITIONS COULD LEAD TO FLOODING CONCERNS, SUPPORTING THE HAZARD
DELINEATION ON THE FORECAST MAP DESPITE RAINFALL AMOUNTS GENERALLY BEING BELOW
REGIONAL HAZARD LEVELS (2" IN 24 HOURS), BUT ARE SUPPORTED VIA COORDINATION
WITH NWS ALASKA REGION AND ALASKA-PACIFIC RIVER FORECAST CENTER.  FLOOD WATCHES
HAVE BEEN ISSUED FOR THE SEWARD PENINSULA AND WESTERN INTERIOR OF ALASKA THAT
CURRENTLY END PRIOR TO DAY 3, BUT MAY BE EXTENDED INTO THE FORECAST PERIOD.  A
SECOND COLD FRONT IS FORECAST TO PUSH THROUGH THE NORTH SLOPE OF ALASKA ON JULY
31-AUGUST 1, AND WHILE NOT FORECAST TO BRING SUBSTANTIAL RAINFALL, MAY YIELD
POSSIBLE HIGH WINDS (EXCEEDING 25 KNOTS) IN ADVANCE OF, AND IMMEDIATELY BEHIND,
THE FRONTAL PASSAGE.



WHILE NOT DISPLAYED ON THE FORECAST MAP, MARGINAL FIRE WEATHER CONCERNS ARE
FORECAST BY THE STORM PREDICTION CENTER ACROSS PORTIONS OF THE WEST EARLY IN
WEEK-1.  THEY SUGGEST DRY THUNDERSTORM CHANCES ARE ELEVATED FOR PORTIONS OF THE
GREAT BASIN AND CENTRAL ROCKIES ON JULY 31.  PRESENCE OF DRY FUELS IS ALSO
ANTICIPATED ALONG WITH LOW RELATIVE HUMIDITY, WARM TEMPERATURES, AND SOMEWHAT
WINDY CONDITIONS FOR PARTS OF THE GREAT BASIN, NORTHERN INTERMOUNTAIN REGION,
AND NORTHERN ROCKIES FOR JULY 31-AUGUST 2.

FOR FRIDAY AUGUST 05 - THURSDAY AUGUST 11: THE 500-HPA PATTERN AT THE BEGINNING
OF WEEK-2 IS FORECAST TO FEATURE RIDGING ACROSS THE CENTRAL CONUS, WITH THE
GREATEST POSITIVE HEIGHT ANOMALIES ACROSS THE GREAT LAKES.  AS THE WEEK
PROGRESSES, DYNAMICAL MODEL ENSEMBLE GUIDANCE SUPPORTS 500-HPA TROUGHING
BUILDING ACROSS THE NORTHEAST AND MODEST AMPLIFICATION A RIDGE FOCUSED OVER THE
ROCKIES AND CENTRAL CONUS.



TWO AREAS ARE HIGHLIGHTED FOR A SLIGHT RISK OF MUCH ABOVE-NORMAL TEMPERATURES
DURING WEEK-2.  THE FIRST REGION IS FOR PORTIONS OF THE NORTHEAST AND NEW
ENGLAND ON AUGUST 5TH, WHERE THE GEFS PROBABILISTIC EXTREMES TOOL INDICATES AT
LEAST A 20% CHANCE OF EXCEEDING THE 85TH PERCENTILE OF CLIMATOLOGICAL MAXIMUM
TEMPERATURES.  THE SECOND AREA IS ADJACENT TO THE GULF OF MEXICO AND UP THE
EASTERN SEABOARD THROUGH THE CAROLINAS FOR AUGUST 5-8.  THE GEFS PROBABILISTIC
EXTREME GUIDANCE SUPPORTS SIMILAR CIRCUMSTANCES FOR THIS WARMTH RELATIVE TO THE
FORMER REGION.  GEFS, EUROPEAN ENSEMBLE, AND NAEFS GUIDANCE ALSO INDICATE THIS
PORTION OF THE SOUTHEAST AS THE MOST LIKELY CONUS AREA TO EXPERIENCE
ABOVE-NORMAL TEMPERATURES DURING THE 6-10 DAY PERIOD.



TWO EASTERLY WAVES NEAR 10N-20W AND 12N-35W BEAR CONTINUED MONITORING FOR
TROPICAL CYCLOGENESIS THROUGHOUT THE TWO WEEK FORECAST PERIOD.  CURRENTLY THE
NATIONAL HURRICANE CENTER (NHC) GIVES THESE SYSTEMS A 40% AND 30% CHANCE
RESPECTIVELY OF FORMING A TROPICAL CYCLONE THROUGH AUGUST 2.  GEFS GUIDANCE HAS
DIFFICULTY TODAY TRACKING THESE SYSTEMS BEYOND THE LESSER ANTILLES, HOWEVER
SOME CFS MEMBERS TRACK THE MORE EASTERN DISTURBANCE THROUGH HISPANIOLA IN
WEEK-2.  DYNAMICAL MODEL GUIDANCE HAS TRENDED WEAKER RELATIVE TO YESTERDAY IN
REGARDS TO THE EASTERNMOST SYSTEM`S FORECAST INTENSITY, WITH UNFAVORABLE
ENVIRONMENTAL CONDITIONS EXPECTED ACROSS THE CENTRAL TROPICAL ATLANTIC.  EVEN
IF THESE SYSTEMS DO NOT IMPACT U.S. INTERESTS AS TROPICAL CYCLONES, THEY MAY
STILL BRING HEAVY RAIN TO PUERTO RICO.  ADDITIONAL INFORMATION ON THESE SYSTEMS
ARE AVAILABLE THROUGH THE NHC (HTTP://WWW.NHC.NOAA.GOV) OR GLOBAL TROPICAL
HAZARDS OUTLOOK
(HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/PRECIP/CWLINK/GHAZARDS/INDEX.PHP).



ACCORDING TO THE U.S. DROUGHT MONITOR (USDM), RELEASED ON JULY 28, SEVERE, OR
GREATER INTENSITY DROUGHT COVERS 5.97 PERCENT OF THE U.S. DROUGHT MONITOR AREAS
(INCLUDING ALASKA, HAWAII, AND PUERTO RICO).  THIS IS A NEARLY THREE-TENTHS OF
A PERCENT INCREASE COMPARED TO THE PRIOR WEEK.  THIS INCREASE IS DUE TO AN
EXPANSION OF SHORT-TERM SEVERE DROUGHT ACROSS THE EASTERN CONUS, PRIMARILY
ACROSS THE LOWER-MISSISSIPPI VALLEY.

FORECASTER: DANIEL HARNOS

$$




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