Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2
000
FXUS21 KWNC 291838
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT JULY 29 2014

SYNOPSIS: A STRONG AREA OF UPPER-LEVEL LOW PRESSURE IS FORECAST TO PERSIST
ACROSS THE EASTERN U.S. THROUGH THE END OF JULY BEFORE IT BEGINS TO WEAKEN. AN
AREA OF UPPER-LEVEL HIGH PRESSURE IS EXPECTED TO REMAIN CENTERED OVER THE
WESTERN U.S. A SURFACE LOW IS EXPECTED TO CROSS MAINLAND ALASKA THIS WEEKEND.

HAZARDS

MUCH ABOVE-NORMAL TEMPERATURES FOR PARTS OF THE PACIFIC NORTHWEST AND NORTHERN
INTERMOUNTAIN WEST, FRI-TUE, AUG 1-AUG 5.

HEAVY RAIN FOR COASTAL AREAS OF THE SOUTHEAST, FRI-SUN, AUG 1-3.

FLASH FLOODING POSSIBLE FOR PARTS OF THE SOUTHWEST, FRI-SUN, AUG 1-3.

SEVERE DROUGHT FOR PARTS OF THE GREAT PLAINS, SOUTHWEST, PACIFIC NORTHWEST,
GREAT BASIN, AND CALIFORNIA.

DETAILED SUMMARY

FOR FRIDAY AUGUST 01 - TUESDAY AUGUST 05: FLASH FLOODING IS LIKELY TO REMAIN
THE MAJOR HAZARD ACROSS THE SOUTHWEST AS SOUTHEAST FLOW INCREASES MONSOON
MOISTURE AND RESULTS IN THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL THROUGH THE
WEEKEND. THE 6Z GFS MODEL INDICATES THAT THE POTENTIAL FOR PRECIPITABLE WATER
VALUES TO EXCEED 1 INCH ACROSS MUCH OF ARIZONA BY SUNDAY. BEYOND THE WEEKEND,
MODEL SOLUTIONS VARY ON WHETHER THE MID-LEVEL FLOW REMAINS SOUTHEASTERLY OR
BECOMES MORE WESTERLY ACROSS THE DESERT SOUTHWEST. IN ADDITION TO THE FLASH
FLOODING HAZARD, OUTFLOW FROM THUNDERSTORMS IS CAPABLE OF CAUSING BLOWING DUST
ACROSS SOUTHERN ARIZONA.



UNSEASONABLY LOW 500-HPA HEIGHTS, ENHANCED LOW-LEVEL CONVERGENCE ALONG A
STATIONARY FRONT, AND ABUNDANT MOISTURE ARE EXPECTED TO RESULT IN HEAVY
RAINFALL ACROSS COASTAL AREAS OF THE SOUTHEAST FROM FRIDAY THROUGH AT LEAST
SUNDAY.



MAXIMUM TEMPERATURES ARE FORECAST TO AVERAGE AROUND 10 DEGREES F BELOW-NORMAL
ACROSS THE SOUTHERN GREAT PLAINS FROM FRIDAY THROUGH MONDAY. MEANWHILE, THE
AMPLIFIED RIDGE OVER THE WESTERN U.S. IS LIKELY TO MAINTAIN MUCH ABOVE-NORMAL
TEMPERATURES THROUGH AT LEAST TUESDAY ACROSS THE INTERIOR PACIFIC NORTHWEST AND
NORTHERN INTERMOUNTAIN WEST. NUMEROUS WILDFIRES CONTINUE TO BURN ACROSS THESE
AREAS ALONG WITH CALIFORNIA, NEVADA, AND UTAH. CURRENTLY, THE LARGEST WILDFIRE
WITH NEARLY 400,000 ACRES BURNED IS LOCATED IN SOUTHEAST OREGON. A FEW DRY
THUNDERSTORMS COULD IGNITE ADDITIONAL WILDFIRES ACROSS THE NORTHERN GREAT BASIN
AND PACIFIC NORTHWEST.



THE COVERAGE OF SHOWERS IS EXPECTED TO INCREASE ACROSS MAINLAND ALASKA BY EARLY
NEXT WEEK, BUT PRECIPITATION AMOUNTS ARE LIKELY TO REMAIN BELOW HAZARDS
CRITERIA.

FOR WEDNESDAY AUGUST 06 - TUESDAY AUGUST 12: SPREAD AMONGST THE 0Z GFS ENSEMBLE
MEMBERS INCREASES REGARDING THE AMPLITUDE OF THE RIDGE (TROUGH) OVER THE
WESTERN (EASTERN) U.S. DURING WEEK-2. A SLIGHT RISK OF ABOVE-NORMAL
TEMPERATURES FOR PARTS OF THE PACIFIC NORTHWEST ON AUGUST 6 AND 7 IS POSTED ON
THE PROBABILISTIC WEEK-2 HAZARDS OUTLOOK. THIS WEEK-2 HAZARD AREA IS BASED ON
THE POTENTIAL THAT THE UPPER-LEVEL RIDGE MAY NOT WEAKEN AS QUICKLY AS FORECAST
BY THE MODELS. ALSO, THE SLIGHT RISK IS CONSISTENT WITH INCREASING SPREAD AMONG
THE 0Z GFS ENSEMBLE MEMBERS.



AS OF 2PM EDT ON TUESDAY, A TROPICAL WAVE IS LOCATED NEAR 10N/40W. THIS WELL
ORGANIZED TROPICAL WAVE SHOULD BE MONITORED AS IT TRACKS INTO THE CENTRAL
ATLANTIC.



BASED ON THE LATEST DROUGHT MONITOR VALID ON JULY 22, SEVERE TO EXCEPTIONAL
DROUGHT CONTINUED TO DECREASE AND NOW COVERS 23.9 PERCENT OF THE CONTINENTAL
U.S.

FORECASTER: BRAD PUGH

$$



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