Prognostic Meteorological Discussion
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FXUS21 KWNC 031953
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 03 2015

SYNOPSIS: A FRONTAL SYSTEM IS FORECAST TO MOVE EASTWARD ACROSS THE NORTHERN
CONUS DURING THE 3-7 DAY OUTLOOK PERIOD, WEAKENING AS IT APPROACHES NEW
ENGLAND. A COLD FRONT IS PREDICTED TO MOVE DEEP INTO THE SOUTHEAST, AND
GRADUALLY BECOME STATIONARY. THESE TWO SYSTEMS ARE EXPECTED TO BE THE MAIN
PRODUCERS OF PRECIPITATION DURING THE 3-7 DAY PERIOD ACROSS THE CONTIGUOUS U.S.
TROPICAL STORM GUILLERMO, CURRENTLY LOCATED OVER THE EAST-CENTRAL TROPICAL
PACIFIC OCEAN, IS FORECAST TO PASS CLOSE TO, PERHAPS JUST NORTH OF, THE
HAWAIIAN ISLANDS AT THE BEGINNING OF THE OUTLOOK PERIOD. A FAIRLY LARGE LOW
PRESSURE SYSTEM IS ANTICIPATED TO AFFECT SOUTHWESTERN AND SOUTHERN ALASKA.

HAZARDS

HEAVY RAIN FOR THE OHIO AND TENNESSEE VALLEYS, MID-ATLANTIC REGION, AND
SOUTHERN NEW ENGLAND, THU-FRI, AUG 6-7.

HEAVY RAIN FOR PORTIONS OF KANSAS AND MISSOURI, THU-FRI, AUG 6-7.

PERIODS OF HEAVY RAIN ACROSS MUCH OF THE DAKOTAS AND MINNESOTA, THU-SUN, AUG
6-9.

HEAVY RAIN FOR IOWA AND ILLINOIS, SAT-SUN, AUG 8-9.

HEAVY RAIN FOR NORTHERN FLORIDA AND SOUTHERN GEORGIA, SAT-SUN, AUG 8-9.

SEVERE DROUGHT FOR PARTS OF THE WESTERN THIRD OF THE CONUS, SOUTHERN GEORGIA,
SOUTHERN FLORIDA, NORTH CAROLINA AND HAWAII.

SLIGHT CHANCE OF MUCH ABOVE-NORMAL TEMPERATURES ACROSS THE SOUTHERN PLAINS AND
LOWER MISSISSIPPI VALLEY, TUE-THU, AUG 11-13.

DETAILED SUMMARY

FOR THURSDAY AUGUST 06 - MONDAY AUGUST 10: AS A LOW PRESSURE CENTER MOVES
ACROSS THE MID-ATLANTIC REGION AND OFF THE NORTHEAST COAST, THE TRAILING COLD
FRONT IS FORECAST TO MOVE INTO THE DEEP SOUTH, BEFORE BECOMING STATIONARY.
SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS MUCH OF THIS REGION, THOUGH THE
BEST CHANCES FOR HEAVY RAIN (1-2 INCHES) EXTEND FROM EASTERN SECTIONS OF BOTH
KENTUCKY AND TENNESSEE GENERALLY NORTHEASTWARD TO INCLUDE MUCH OF THE
MID-ATLANTIC AND SOUTHERN NEW ENGLAND. ANOTHER AREA THAT IS ANTICIPATED TO
RECEIVE COMPARABLE RAINFALL AMOUNTS IS NORTHEASTERN KANSAS AND WESTERN
MISSOURI. SEVERAL DAYS LATER, RELATIVELY SMALL-SCALE AREAS OF HEAVY RAIN ARE
ANTICIPATED OVER PORTIONS OF THE MIDWEST, AND NORTHERN FLORIDA AND SOUTHERN
GEORGIA. PERIODS OF HEAVY RAIN ARE FORECAST FOR THE DAKOTAS AND MINNESOTA
DURING MOST OF THIS PERIOD, THOUGH THIS IS LARGELY DUE TO AN APPROACHING
FRONTAL SYSTEM FROM THE NORTHERN ROCKIES. AT THE PRESENT TIME, NO AREAS OF
SEVERE WEATHER ARE HIGHLIGHTED, FOR ANY OF THE REGION GENERALLY ENCOMPASSING
THE NORTHERN AND CENTRAL PLAINS, THE MIDDLE MISSISSIPPI VALLEY, AND THE
TENNESSEE/OHIO VALLEYS. THE MAIN REASON FOR THIS IS THE EXPECTATION OF OUTFLOW
BOUNDARIES ASSOCIATED WITH OVERNIGHT THUNDERSTORM CLUSTERS (MCS`S), AND THEIR
TENDENCY TO STABILIZE THE BOUNDARY LAYER THE FOLLOWING AFTERNOON. THESE OUTFLOW
BOUNDARIES MAKE IT VERY CHALLENGING TO PINPOINT WHERE SUBSEQUENT CONVECTION MAY
DEVELOP.



ACCORDING TO THE USDA FOREST SERVICE, THERE ARE NEARLY 2 DOZEN LARGE WILDFIRES
IN PROGRESS ACROSS THE WEST COAST STATES, WITH THE GREATEST CONCENTRATION OF
WILDFIRES IN CALIFORNIA. FIRES IN THE NORTHWEST AREA OF CALIFORNIA (GENERALLY
NEAR OR IN THE COASTAL MOUNTAINS) HAVE BURNED ANYWHERE FROM 3000 TO 54000
ACRES, AS OF TODAY. THESE WILDFIRES APPEAR TO BE RELATED TO STRONGER WINDS
ASSOCIATED WITH A 500-HPA TROUGH NEAR THE COAST, AND THE PRESENCE OF DRY
VEGETATIVE FUELS IN THIS REGION.



AS OF 5AM HAWAIIAN TIME, TROPICAL STORM GUILLERMO WAS LOCATED ABOUT 630 MILES
EAST-SOUTHEAST OF HILO, HI, MOVING SLOWLY TOWARD THE HAWAIIAN ARCHIPELAGO. IT
IS A STRONG TROPICAL STORM, WITH MAXIMUM SUSTAINED WINDS OF 70 MPH. DYNAMICAL
MODEL GUIDANCE PREDICTS GUILLERMO WILL PASS CLOSE TO THE ISLANDS JUST PRIOR TO,
AND DURING THE FIRST TWO DAYS OF, THE BEGINNING OF THIS PERIOD. THE OFFICIAL
TRACK, ISSUED BY THE CENTRAL PACIFIC HURRICANE CENTER (CPHC) IN HONOLULU, HAS
GUILLERMO PASSING JUST NORTH OF HAWAII AS A STILL-POTENT TROPICAL STORM.
RESIDENTS ACROSS THE 50TH STATE ARE ENCOURAGED TO OBTAIN THE VERY LATEST
INFORMATION ON THIS STORM BY CONSULTING LOCAL NEWS MEDIA, AND/OR THE CPHC AT:
HTTP://WWW.PRH.NOAA.GOV/HNL/CPHC/.



A FAIRLY LARGE LOW PRESSURE SYSTEM IS PREDICTED TO MOVE EASTWARD ACROSS THE
SOUTHERN COAST OF ALASKA DURING THIS PERIOD, BRINGING CLOUDS AND PRECIPITATION.
HOWEVER, AT THIS TIME, NO WEATHER-RELATED HAZARDS ARE EXPECTED WITH THIS SYSTEM.

FOR TUESDAY AUGUST 11 - MONDAY AUGUST 17: BY THE END OF THE 3-7 DAY PERIOD, AND
INTO AT LEAST THE FIRST HALF OF WEEK-2, THE HIGHEST 500-HPA HEIGHTS ASSOCIATED
WITH THE SUBTROPICAL RIDGE ARE FORECAST TO SHIFT FROM THE SOUTHWEST INTO THE
SOUTHERN GREAT PLAINS REGION. THIS FAVORS A SLIGHT RISK OF MUCH ABOVE-NORMAL
TEMPERATURES ACROSS THE SOUTH-CENTRAL CONUS. MID-TROPOSPHERIC TROUGHS ARE
ANTICIPATED NEAR THE PACIFIC COAST, AND THE ATLANTIC COAST STATES.



THE LATEST WEEKLY U.S. DROUGHT MONITOR MAP, RELEASED ON JULY 30TH, SHOWS A
SLIGHT INCREASE IN THE COVERAGE OF SEVERE TO EXCEPTIONAL DROUGHT (D2 TO D4)
ACROSS THE CONTIGUOUS U.S., FROM 16.74 PERCENT TO 17.17 PERCENT. ACCORDING TO
AHPS, RAINFALL HAS BEEN BELOW-NORMAL DURING THE PAST TWO WEEKS FOR MOST AREAS
EAST OF THE MISSISSIPPI RIVER, THOUGH WITH ONE SIGNIFICANT EXCEPTION. FOR MOST
OF THE NORTHWEST QUARTER OF THE FLORIDA PENINSULA, RAINFALL AMOUNTS HAVE RANGED
FROM 5-8 INCHES ABOVE NORMAL, AND EVEN HIGHER IN SOME LOCALIZED AREAS. THIS IS
ASSOCIATED WITH A WEAK AREA OF LOW PRESSURE OVER NORTHERN FLORIDA. IN CONTRAST,
SOUTHERN FLORIDA IS RUNNING A 1-3 INCH RAINFALL DEFICIT DURING THE LAST 14 DAYS.

FORECASTER: ANTHONY ARTUSA

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