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FXUS25 KWNC 261330
PMDDRO
US DROUGHT MONITOR DISCUSSION
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
830 AM EST WED 25 NOV 2009
NATIONAL DROUGHT SUMMARY NOVEMBER 24, 2009
THE NORTHEAST: MILD, UNSETTLED CONDITIONS PREVAILED, WITH
WEEKLY RAINFALL TOTALS EXCEEDING AN INCH FROM NORTHEASTERN
PENNSYLVANIA INTO CENTRAL MAINE. FOR THE SECOND STRAIGHT WEEK,
HOWEVER, RAIN BYPASSED WESTERN PENNSYLVANIAS D0 /ABNORMAL
DRYNESS/, WHERE 7-DAY AVERAGE STREAMFLOWS AND SOIL MOISTURE
LEVELS REMAINED BELOW THE 30TH PERCENTILE. CONSEQUENTLY,
THERE WERE NO CHANGES TO THE CURRENT DROUGHT DEPICTION IN
THE NORTHEAST.
THE MID-ATLANTIC AND SOUTHEAST: A PAIR OF UPPER-AIR LOWS
GENERATED ADDITIONAL RAINFALL ON THE HEELS OF LAST WEEKS
HEAVY DOWNPOURS, BRINGING FURTHER RELIEF FROM LINGERING
LONG-TERM DRYNESS /D0/ IN THE CAROLINAS. CONCERNS REGARDING
GROUNDWATER TABLES AND LONG-TERM PRECIPITATION DEFICITS /180-
AND 365-DAYS/ REMAIN, ESPECIALLY IN SOUTH-CENTRAL NORTH CAROLINA
AND NORTHEASTERN SOUTH CAROLINA. SHORT-TERM DRYNESS CONTINUED
IN CENTRAL AND SOUTHERN FLORIDA, WHERE MODERATE DROUGHT
/D1/ EXPANDED SLIGHTLY WESTWARD FROM THE EAST-CENTRAL COAST.
IN CONTRAST, POCKETS OF HEAVY RAIN /LOCALLY MORE THAN 3 INCHES/
IN NORTHERN FLORIDA PROVIDED RELIEF FROM ABNORMAL DRYNESS /D0/.
THE DELTA: SHOWERS RETURNED TO THE DELTA, EASING SHORT-TERM
/30-DAY/ DEFICITS NEAR THE MOUTH OF THE MISSISSIPPI RIVER.
DROUGHT IS NOT A CONCERN IN THE NORTHERN DELTA, WHERE FLOODING
AND FIELDWORK DELAYS HAVE BEEN PROMINENT.
TEXAS: HEAVY RAIN ACCOMPANIED A SLOW-MOVING STORM SYSTEM OVER
SOUTHERN AND EASTERN TEXAS, REDUCING DROUGHT INTENSITY AND
COVERAGE OVER THE SOUTHERN THIRD OF THE STATE.THREE INCHES OF
RAIN /OR MORE/ WAS OBSERVED FROM CORPUS CHRISTI TO GALVESTON
BAY, EXTENDING INLAND ALMOST TO SAN ANTONIO. MANY AREAS
SOUTH OF VICTORIA REPORTED OVER 5 INCHES OF RAIN /LOCALLY UP
TO 10 INCHES/, RESULTING IN 1- AND 2-CATEGORY IMPROVEMENTS IN
DROUGHT INTENSITY. HOWEVER, THE CORE D3 /EXTREME DROUGHT/
BETWEEN DEL RIO AND SAN ANTONIO RECEIVED SCATTERED, MOSTLY
LIGHT SHOWERS /LESS THAN HALF AN INCH/, WITH LITTLE CHANGE
MADE TO THIS AREA. DESPITE THE RECENT HEAVY RAIN, LONG-TERM
DEFICITS PERSIST, WITH 365-DAY DEPARTURES STILL GREATER THAN
10 INCHES ACROSS SOUTHERN-MOST PORTIONS OF TEXAS. MEANWHILE,
WESTERN AND NORTHERN TEXAS REMAINED UNFAVORABLY DRY; DROUGHT
COVERAGE /D0 AND D1/ INCREASED AROUND LUBBOCK, WHERE 90-DAY
PRECIPITATION DEFICITS HAVE CREPT ABOVE 3 INCHES /LESS THAN
40 PERCENT OF AVERAGE/.
CENTRAL AND NORTHERN PLAINS: DRY, WARMER-THAN-NORMAL WEATHER
CONTINUED DURING THE PAST WEEK. ABNORMALLY DRY /D0/ DESIGNATION
WAS INTRODUCED TO EASTERN MONTANA AND ADJACENT PORTIONS OF
NORTHERN COLORADO, WHERE 30- AND 90-DAY PRECIPITATION STOOD
AT APPROXIMATELY 20 AND 60 PERCENT OF NORMAL, RESPECTIVELY.
PRECIPITATION TOTALS REMAINED AT OR ABOVE AVERAGE OVER THE
CENTRAL GREAT PLAINS IN BOTH THE SHORT AND LONG TERM.
UPPER MIDWEST: A SMALL POCKET OF LOCALLY HEAVY SHOWERS /GREATER
THAN 1 INCH/ IN CENTRAL WISCONSIN PROVIDED ISOLATED RELIEF
TO LINGERING LONG-TERM DRYNESS /D0/, BUT MOST OTHER DROUGHT
AREAS IN THE UPPER MIDWEST WERE GENERALLY PRECIPITATION-FREE
DRY DURING THE PAST WEEK. FOR THE SECOND STRAIGHT WEEK,
TEMPERATURES AVERAGED MORE THAN 10 DEGREES F ABOVE NORMAL FROM
THE DAKOTAS INTO WISCONSIN.
THE WEST: LOCALLY HEAVY RAIN AND MOUNTAIN SNOW IN NORTHERN
CALIFORNIA AS WELL AS WESTERN PORTIONS OF WASHINGTON AND
OREGON PROVIDED FURTHER RELIEF FROM HYDROLOGICAL DROUGHT.
THE ADDITIONAL RECHARGE TO MOUNTAIN SNOWPACKS IN NORTHERN
PORTIONS OF THE WEST WAS IN SHARP CONTRAST TO WORSENING
DROUGHT ACROSS THE SOUTHERN HALF OF THE REGION. PRECIPITATION
DEPARTURES, ALREADY ENHANCED BY A WEAK AND ERRATIC MONSOON,
HAVE INCREASED AS PACIFIC STORMS TRACK PRIMARILY ACROSS THE
NORTHWEST. EXPANSION OF DROUGHT FROM THE SOUTHERN GREAT BASIN
TO THE MEXICO BORDER WAS BASED ON NUMEROUS INPUTS, INCLUDING,
BUT NOT LIMITED TO: UPDATED SOIL MOISTURE PERCENTILES /NLDAS/,
WHICH ARE IN THE LOWEST 5TH PERCENTILE IN SOUTHEAST NEVADA AND
NORTHERN ARIZONA; SNOW WATER EQUIVALENT, WHICH IS LESS THAN
50 PERCENT OF NORMAL OVER MUCH OF THE REGION; STANDARDIZED
PRECIPITATION INDICES /SPI/, WHICH FOR THE CURRENT WATER YEAR
/SINCE OCTOBER 1/ ARE BELOW -1.5 /D3/ IN ARIZONA AND SOUTHERN
UTAH AND ARE YEAR-TO-DATE BELOW -1.5 FOR MOST OF THE SOUTHWEST.
THE SITUATION ACROSS THE SOUTHWEST AND FOUR CORNERS REGION
WILL CONTINUE TO BE MONITORED, WITH ADDITIONAL CHANGES TO THE
DROUGHT DESIGNATION LIKELY IF THE DRY WEATHER PATTERN PERSISTS
INTO THE WINTER.
HAWAII, ALASKA AND PUERTO RICO: SHOWERS WERE OBSERVED IN
HAWAIIS UPSLOPE LOCALES, ALTHOUGH MOST DROUGHT AREAS REMAINED
DRY. DRY, BITTERLY COLD CONDITIONS WERE OBSERVED IN ALASKA,
WITH NO CHANGE MADE TO THE CURRENT D0 AREA. IN PUERTO RICO,
ANOTHER ROUND OF MODERATE TO HEAVY RAIN /1-4 INCHES, LOCALLY
MORE/ PROVIDED ADDITIONAL RECHARGE TO STREAMFLOWS ACROSS WESTERN
AND NORTHERN PORTIONS OF THE ISLAND, WHILE THE SOUTHEASTERN
QUARTER OF PUERTO RICO IS STILL BEING MONITORED FOR POCKETS OF
DEVELOPING DRYNESS. LOOKING AHEAD: A STRONG UPPER-AIR LOW WILL
GENERATE RAIN AND SNOW ACROSS THE CENTRAL AND EASTERN CORN BELT,
WITH PRECIPITATION FROM THIS FEATURE REACHING THE MID-ATLANTIC
AND NORTHEAST BY FRIDAY MORNING. OVER THE WEEKEND, THIS SYSTEM
WILL INTENSIFY OVER THE NORTHEAST, ACCOMPANIED BY STRONG, GUSTY
WINDS AND PERIODS OF SNOW. FARTHER SOUTH, FAVORABLE SHOWERS
OVER FLORIDA WILL GIVE WAY TO DRIER WEATHER BY THE WEEKEND,
WHILE HIGH PRESSURE MAINTAINS SUNNY SKIES FROM THE DELTA INTO
THE FOUR CORNERS AND SOUTHWEST. IN CONTRAST, RAIN AND SNOW WILL
RETURN TO THE NORTHWESTERN QUARTER OF THE NATION BY WEEKS END.
THE GREAT PLAINS WILL REMAIN MOSTLY DRY, ALTHOUGH SOME SNOW MAY
SPILL INTO NORTHERN PORTIONS OF THE REGION OVER THE WEEKEND.
THE CPC 6-10 DAY FORECAST /NOVEMBER 30 DECEMBER 4/ CALLS FOR
BELOW-NORMAL TEMPERATURES OVER MOST OF THE CONTIGUOUS U.S., WITH
NEAR- TO ABOVE-NORMAL TEMPERATURES CONFINED TO THE WEST COAST
AND ALASKA. ABOVE-NORMAL PRECIPITATION IS ANTICIPATED ACROSS
THE EASTERN QUARTER OF THE NATION, WHILE DRIER-THAN-NORMAL
CONDITIONS ARE LIKELY IN THE NORTHWEST. AUTHOR: ERIC
LUEBEHUSEN, UNITED STATES DEPARTMENT OF AGRICULTURE.
DROUGHT INTENSITY CATEGORIES...
D0 ABNORMALLY DRY...
D1 MODERATE DROUGHT...
D2 SEVERE DROUGHT...
D3 EXTREME DROUGHT...
D4 EXCEPTIONAL DROUGHT
DROUGHT TYPES...
USED ONLY WHEN IMPACTS DIFFER...
A AGRICULTURAL...
H HYDROLOGIC.
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