367
FXUS21 KWNC 212017
PMDTHR
US HAZARDS ASSESSMENT
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EST NOVEMBER 21 2008
SYNOPSIS: TEMPERATURES ARE EXPECTED TO BE COLDER THAN NORMAL ACROSS A LARGE
PORTION OF THE LOWER 48 STATES, AND WARMER THAN NORMAL OVER MOST OF ALASKA
DURING THIS PERIOD. DOWNWIND OF THE GREAT LAKES, SNOW SQUALLS WILL LIKELY
FOLLOW THE OCCASIONAL PASSAGE OF STORM SYSTEMS, AND THERE WILL BE AN
OPPORTUNITY FOR SIGNIFICANT SNOWFALL OVER INTERIOR NEW ENGLAND EARLY IN THE
ASSESSMENT PERIOD. THE WESTERN CONUS IS LIKELY TO EXPERIENCE AN OVERALL
INCREASE IN STORMINESS, ESPECIALLY ACROSS CALIFORNIA AND THE SOUTHWEST. IN
ALASKA, MOST OF THE STORM ACTIVITY IS EXPECTED TO BE ACROSS THE SOUTHERN
COASTAL AREAS DURING MUCH OF THIS PERIOD, WITH A TENDENCY FOR THE STORM TRACK
TO THEN SHIFT TOWARDS THE BERING SEA COAST.
HAZARDS
HEAVY PRECIPITATION FOR NEW ENGLAND, NOVEMBER 25-26.
HEAVY LAKE EFFECT SNOWS DOWNWIND OF THE GREAT LAKES, NOVEMBER 25-26.
CONTINUED SEVERE DROUGHT IN PARTS OF THE WEST, SOUTHERN TEXAS, NORTHERN
WISCONSIN, SOUTHEAST AND OHIO VALLEY, WITH SOME RELIEF IN CALIFORNIA.
DETAILED SUMMARY
FOR MONDAY NOVEMBER 24 - WEDNESDAY NOVEMBER 26: COLD TEMPERATURES WILL PREVAIL
ACROSS THE EAST DURING THIS PERIOD. CLOUDINESS IS LIKELY TO INCREASE ACROSS NEW
YORK AND NEW ENGLAND AS AN AREA OF LOW PRESSURE MOVES ACROSS THE GREAT LAKES
REGION AND REDEVELOPS OVER SOUTHERN NEW ENGLAND. THE COMBINATION OF THIS
DEVELOPING STORM AND A HIGH PRESSURE CENTER NEAR NEWFOUNDLAND WILL RESULT IN
STRENGTHENING SOUTHEASTERLY FLOW OF RELATIVELY MILD, MOIST AIR OFF THE
NORTHWEST ATLANTIC. PRECIPITATION ALONG THE NEW ENGLAND COAST MAY START AS
SNOW, BUT IT SHOULD CHANGE OVER TO RAIN QUICKLY. IT WOULD NOT BE UNREASONABLE
TO EXPECT 25 TO 35 KT WINDS NEAR THE COAST NORTH OF THE STORM CENTER,
ESPECIALLY IF A LOW-LEVEL JET FORMS. GFS AND ECMWF MODEL GUIDANCE SUGGESTS THAT
THIS EVENT WILL BE PRIMARILY A HEAVY RAIN EVENT FOR MOST AREAS, THOUGH IN THE
HIGHER ELEVATIONS OF FAR NORTHERN AND FAR WESTERN NEW ENGLAND PRECIPITATION
SHOULD REMAIN AS ALL SNOW. WITH THE STORM EXPECTED TO MEANDER ACROSS THE REGION
FOR SEVERAL DAYS, THIS IS LIKELY TO BE A SIGNIFICANT SNOWFALL EVENT FOR THESE
FAR INTERIOR AREAS. IN THE GREAT LAKES REGION, SNOW SQUALLS AND REDUCED
VISIBILITIES ARE LIKELY TO POSE A PROBLEM FOR DOWNWIND AREAS. IN THE WEST, AN
INCREASE IN PRECIPITATION IS ANTICIPATED. UP TO A THIRD OF AN INCH OF RAIN MAY
FALL ACROSS COASTAL AREAS OF SOUTHERN CALIFORNIA. ELSEWHERE, A TROUGH IN THE
WESTERLIES NEAR THE HAWAIIAN ISLANDS WILL CONTRIBUTE TO LOCALLY HEAVY RAINS
JUST PRIOR TO THIS PERIOD, POSSIBLY EXTENDING INTO MONDAY. BEYOND THAT, DRIER
CONDITIONS ARE EXPECTED AS THE USUAL TRADEWIND PATTERN BECOMES REESTABLISHED.
IN ALASKA, SOUTHERN COASTAL AREAS WILL BE INFLUENCED BY OCCASIONAL PACIFIC
CYCLONE ACTIVITY. ANCHORAGE CAN EXPECT SNOW DURING THIS PERIOD WITH HIGHS IN
THE 20'S, WHILE FAIRBANKS MAY GET LIGHT SNOW LATE IN THE PERIOD, WITH HIGH'S
ABOUT TEN DEGREES COLDER THAN ANCHORAGE.
FOR THURSDAY NOVEMBER 27 - MONDAY DECEMBER 01: THE GULF OF ALASKA STORM TRACK
IS FORECAST TO SHIFT TOWARDS THE SOUTHERN BERING SEA COAST DURING THIS PERIOD,
ENHANCING PRECIPITATION ACROSS THE EASTERN ALEUTIANS AND BRISTOL BAY REGION.
NEAR TO ABOVE MEDIAN PRECIPITATION IS FORECAST ACROSS THE SOUTHWESTERN AND
SOUTH-CENTRAL CONUS AS AN UPPER TROUGH MOVES ACROSS THAT AREA. AN AREA WHICH
NEEDS TO BE MONITORED DURING THIS PERIOD IS THE WESTERN AND CENTRAL GULF COAST
REGION. MODEL GUIDANCE INDICATES THAT MORE SIGNIFICANT GULF MOISTURE INFLOW MAY
BE AVAILABLE TO A FRONTAL SYSTEM APPROACHING THE AREA FROM THE WEST. IN
ADDITION, UPPER-LEVEL DYNAMICS SEEM TO BE MORE FAVORABLE FOR GENERATING STRONG
TO SEVERE THUNDERSTORMS. THERE IS TOO MUCH UNCERTAINTY AT THIS TIME TO
HIGHLIGHT THE REGION ON OUR COMPOSITE MAP, BUT THE SITUATION DOES BEAR
WATCHING. MOST OF THE CONTIGUOUS US CAN EXPECT SURFACE TEMPERATURES TO BE BELOW
NORMAL FOR THIS PERIOD.
FOR TUESDAY DECEMBER 02 - FRIDAY DECEMBER 05: NO SPECIFIC HAZARDS CAN BE
IDENTIFIED RELIABLY AT THIS RANGE, OTHER THAN THE LONG-TERM DROUGHT AREAS
DEPICTED ON OUR NATIONAL COMPOSITE MAP. DROUGHT IS EXPECTED TO PERSIST ACROSS
WISCONSIN, SOUTH-CENTRAL TEXAS, PARTS OF THE INTERIOR SOUTHEAST, AND INTERIOR
SOUTHERN CALIFORNIA.
FORECASTER: ANTHONY ARTUSA
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