Climate Prediction Center

US HAZARDS ASSESSMENT
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EDT MAY 08 2008

SYNOPSIS: THIS ASSESSMENT PERIOD WILL HAVE AN ACTIVE WEATHER PATTERN. A SURFACE LOW PRESSURE SYSTEM WILL DEVELOP OVER THE MIDDLE AND LOWER MISSISSIPPI VALLEY BRINGING RAIN TO MOST OF THE EASTERN HALF OF THE CONUS AS IT MOVES EASTWARD ACROSS THE CONUS. THERE IS A RELATIVELY BROAD AREA OF POSSIBLE SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHEAST AND MIDDLE ATLANTIC AS THIS LOW PRESSURE SYSTEM PASSES THROUGH THIS AREA. AS THIS STORM SYSTEM DEEPENS AND REACHES THE MIDDLE ATLANTIC AND NORTHEASTERN COAST, THESE REGIONS MAY EXPERIENCE HIGH WINDS WHICH COULD CAUSE TIDAL SURGES, COASTAL FLOODING, AND BEACH EROSION. ANOTHER SURFACE LOW PRESSURE SYSTEM MAY DEVELOP OVER THE CENTRAL PLAINS EARLY NEXT WEEK WHICH COULD PRODUCE MORE RAIN FOR THE EASTERN TWO THIRDS OF THE CONUS.

HAZARDS

SEVERE THUNDERSTORMS FROM THE TENNESSEE VALLEY EASTWARD INTO THE CAROLINAS AND SOUTHERN VIRGINIA ON SUNDAY MAY 11.
HEAVY RAIN OVER PARTS OF THE TENNESSEE VALLEY, OHIO VALLEY, MIDDLE ATLANTIC, SOUTHEAST, AND NORTHEAST MAY 11-MAY 12.
HIGH WINDS OVER THE MIDDLE ATLANTIC AND NORTHEAST COAST MAY 12-MAY 13.
ONGOING LOCALIZED RIVER FLOODING OVER THE MIDDLE AND LOWER MISSISSIPPI VALLEY.
SEVERE DROUGHT PERSISTS IN PARTS OF THE PLAINS, WESTERN US, WITH SOME RELIEF POSSIBLE IN THE SOUTHEAST.
ELEVATED WILDFIRE RISK MAY 12 AND MAY 13 ACROSS PARTS OF THE SOUTHWEST AND THE SOUTHERN PLAINS.

DETAILED SUMMARY

FOR SUNDAY MAY 11 - TUESDAY MAY 13: A SURFACE LOW PRESSURE SYSTEM WILL MOVE ACROSS THE OHIO VALLEY EARLY IN THIS PERIOD. A NEGATIVELY TILTED UPPER LEVEL SHORTWAVE, COMBINED WITH SUFFICIENT MOISTURE INFLOW AND INSTABILITY WILL PROVIDE CONDITIONS FOR POSSIBLE SEVERE THUNDERSTORMS ACROSS THE TENNESSEE VALLEY EASTWARD INTO THE CAROLINAS AND SOUTHERN VIRGINIA ON SUNDAY MAY 11. AS THE STORM SYSTEM MIGRATES INTO THE NORTHEAST, PARTS OF THE TENNESSEE VALLEY, OHIO VALLEY, MIDDLE ATLANTIC, SOUTHEAST, AND NORTHEAST COULD RECEIVE HEAVY RAIN MAY 11-MAY 12. AS THE LOW DEEPENS AND MOVES ONTO THE NORTHEAST/MID-ATLANTIC COAST, COASTAL REGIONS IN THOSE AREAS COULD EXPERIENCE HIGH WINDS. THESE HIGH WINDS AND STRONG LOW PRESSURE CAN LEAD TO TIDAL SURGES, COASTAL FLOODING, AND BEACH EROSION. RAIN PRODUCED FROM THIS SURFACE LOW PRESSURE SYSTEM WILL ALSO CONTINUE LOCALIZED RIVER FLOODING OVER PORTIONS OF THE MIDDLE AND LOWER MISSISSIPPI VALLEY. ANTICIPATED STRONG SOUTHWESTERLY WINDS AND LOW RELATIVE HUMIDITIES WILL LEAD TO CRITICAL WILDFIRE CONDITIONS ACROSS PARTS OF THE SOUTHWEST AND SOUTHERN PLAINS MAY 12-MAY 13. LONG TERM DROUGHT PERSISTS IN PARTS OF THE PLAINS, WESTERN US, WITH SOME RELIEF POSSIBLE IN THE SOUTHEAST.

FOR WEDNESDAY MAY 14 - SUNDAY MAY 18: MODELS DEPICT A DEEP UPPER LEVEL TROUGH DEVELOPING OVER THE EASTERN HALF OF THE CONUS OVER THE EARLIER PART OF THIS PERIOD, ALTHOUGH THERE ARE SIGNIFICANT TIMING AND INTENSITY DIFFERENCES. THIS SURFACE LOW PRESSURE SYSTEM COULD BRING RAIN TO THE EASTERN HALF OF THE CONUS AS IT MOVES THROUGH THE EASTERN CONUS. IN GENERAL, MODELS INDICATE AN AMPLIFIED PATTERN OF A TROUGH OVER THE EASTERN TWO THIRDS OF THE CONUS AND A RIDGE OVER THE WESTERN THIRD OF THE CONUS AND BELOW NORMAL HEIGHTS OVER ALASKA. BELOW NORMAL TEMPERATURES ARE FORECAST FOR THE EASTERN TWO THIRDS OF THE CONUS AND SOUTHERN COAST OF ALASKA, WHILE ABOVE NORMAL TEMPERATURES ARE EXPECTED OVER THE WESTERN THIRD OF THE CONUS AND NORTHERN ALASKA. THE WESTERN THIRD OF THE CONUS AND SOUTHERN ALASKA IS ANTICIPATED TO HAVE WETTER THAN NORMAL CONIDTIONS AND DRIER THAN NORMAL CONDITIONS ARE FORECAST FOR NORTHERN ALASKA AND THE WESTERN TWO THIRDS OF THE CONUS.

FOR MONDAY MAY 19 - THURSDAY MAY 22: THE 6Z GFS INDICATES A CONTINUED UPPER LEVEL PATTERN OF TROUGHING ACROSS THE EASTERN TWO THIRDS OF THE CONUS AND RIDGING ACROSS THE WESTERN THIRD OF THE CONUS. DUE TO THE INHERENT UNCERTAINTY FOR THIS PERIOD, NO HAZARDS CAN BE MADE AT THIS TIME.

FORECASTER: MELISSA OU

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