424
FXUS21 KWNC 121942
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EDT AUGUST 12 2013
SYNOPSIS: EARLY IN THE PERIOD, A FRONTAL SYSTEM IS EXPECTED TO SINK SOUTHWARD
OVER THE SOUTHEASTERN U.S. BY THURSDAY, BRINGING UNSETTLED WEATHER TO THIS
AREA. SURFACE HIGH PRESSURE IS EXPECTED TO DOMINATE MOST OF THE LOWER 48
STATES, EXCEPT FOR THE SOUTHEAST. AREAS OF SURFACE LOW PRESSURE ARE FORECAST
OVER MUCH OF ALASKA.
HAZARDS
HEAVY RAIN FOR PARTS OF THE SOUTHEAST, THU-SAT, AUG 15-17.
ENHANCED WILDFIRE RISK FOR PORTIONS OF EASTERN ALASKA, THU-SUN, AUG 15-18.
FLOODING FOR PARTS OF KANSAS AND MISSOURI, THU-FRI, AUG 15-16.
SEVERE DROUGHT FOR PARTS OF THE GREAT PLAINS, RIO GRANDE VALLEY, ROCKIES,
SOUTHWEST, GREAT BASIN, CALIFORNIA, ALASKA, AND HAWAII.
DETAILED SUMMARY
FOR THURSDAY AUGUST 15 - MONDAY AUGUST 19: A FRONTAL SYSTEM IS FORECAST TO
STALL ACROSS THE SOUTHEAST BY THURSDAY, BRINGING HEAVY RAIN TO PARTS OF THE
SOUTHEAST THURSDAY TO SATURDAY. MODELS INDICATE THE POTENTIAL FOR GREATER THAN
2 INCHES OF RAIN IN A 24-HOUR PERIOD IN SOME OF THESE AREAS. EXPECTED HEAVY
RAIN MAY SUPPORT LOCALIZED FLASH FLOODING IN SOME AREAS.
AN UPPER-LEVEL RIDGE IS PREDICTED TO CONTINUE ACROSS EASTERN ALASKA FOR MOST OF
THE PERIOD AND IS EXPECTED TO LEAD TO HOT, DRY WEATHER, POTENTIALLY ELEVATING
THE RISK FOR WILDFIRES ACROSS EASTERN ALASKA THURSDAY TO SUNDAY.
ANTECEDENT RAINFALL AND THE EXPECTATION OF ADDITIONAL HEAVY PRECIPITATION HAS
THE POTENTIAL TO LEAD TO FLOODING OVER PORTIONS OF THE CENTRAL PLAINS AND
MIDDLE MISSISSIPPI VALLEY.
SOME MODELS ARE INDICATING THE POTENTIAL FOR A SURFACE LOW TO DEVELOP OVER THE
BAY OF CAMPECHE TOWARDS THE END OF THE WEEK. HOWEVER, THERE ARE SIGNIFICANT
MODEL DIFFERENCES REGARDING THIS FEATURE. THE 6Z AND 12Z OPERATIONAL GFS
INDICATE THIS SURFACE LOW MAY TRACK TOWARDS THE GULF COAST STATES, WHEREAS THE
00Z OPERATIONAL ECMWF PREDICTS THE SURFACE LOW QUICKLY DISSIPATING AS IT TRACKS
WESTWARD TOWARDS MEXICO. CURRENTLY, WPC AND NHC ARE IN FAVOR OF THE ECMWF
SOLUTION, THEREFORE, NO ASSOCIATED HAZARDS ARE SPECIFIED AT THIS TIME.
THERE IS A LOW PROBABILITY (10%) OF A TROPICAL CYCLONE FORMING IN THE CENTRAL
PACIFIC WITHIN THE NEXT 48 HOURS WITH A LOW POTENTIAL FOR THIS CYCLONE TO
IMPACT HAWAII DURING THIS PERIOD, WITH THE MOST LIKELY IMPACTS BEING LOCALIZED
HEAVY RAIN AND HIGH SURF. DUE TO THE HIGH UNCERTAINTY ASSOCIATED WITH THE
EVOLUTION OF THIS STORM, AND THE POSSIBILITY FOR THE CYCLONE TO TRACK TOO FAR
SOUTH TO IMPACT HAWAII, NO SPECIFIC HAZARDS ARE DESIGNATED AT THIS TIME.
FOR TUESDAY AUGUST 20 - MONDAY AUGUST 26: IN GENERAL, MODELS INDICATE
NEAR-NORMAL MID-LEVEL (500-HPA) HEIGHTS DURING THIS PERIOD FOR MOST OF THE
CONUS, AND CENTRAL AND EASTERN ALASKA, WITH BELOW NORMAL HEIGHTS ACROSS THE
ALEUTIANS. NEAR TO ABOVE-NORMAL TEMPERATURES ARE PREDICTED ACROSS MUCH OF THE
NORTHERN TIER AND THE WESTERN HALF OF THE CONUS, SOUTHERN FLORIDA, AND ALASKA.
BELOW-NORMAL TEMPERATURES ARE FORECAST FOR PARTS OF THE CENTRAL PLAINS, MIDDLE
AND LOWER MISSISSIPPI VALLEYS, AND THE OHIO AND TENNESSEE VALLEYS. THERE ARE
ENHANCED CHANCES FOR ABOVE-MEDIAN PRECIPITATION ACROSS THE EASTERN THIRD OF THE
CONUS, PARTS OF THE CENTRAL AND SOUTHERN PLAINS, THE SOUTH COAST OF ALASKA,
ALEUTIANS, AND THE ALASKAN PANHANDLE. MEDIAN TO BELOW-MEDIAN PRECIPITATION IS
EXPECTED ELSEWHERE. CURRENTLY, THE ONLY ANTICIPATED HAZARD DURING THIS TIME
RANGE IS THE PERSISTENCE OF LONG-TERM DROUGHT.
FORECASTER: MELISSA OU
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