FXUS25 KWNC 182021
PMDDRO
US DROUGHT MONITOR DISCUSSION
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
830 AM EST THU 18 MAR 2010
NATIONAL DROUGHT SUMMARY MARCH 16, 2010 THE DISCUSSION IN
THE LOOKING AHEAD SECTION IS SIMPLY A DESCRIPTION OF WHAT
THE OFFICIAL NATIONAL GUIDANCE FROM THE NATIONAL WEATHER
SERVICE /NWS/ NATIONAL CENTERS FOR ENVIRONMENTAL PREDICTION
IS DEPICTING FOR CURRENT AREAS OF DRYNESS AND DROUGHT. THE
NWS FORECAST PRODUCTS UTILIZED INCLUDE THE HPC 5-DAY QPF
AND 5-DAY MEAN TEMPERATURE PROGS, THE 6-10 DAY OUTLOOKS
OF TEMPERATURE AND PRECIPITATION PROBABILITY, AND THE 8-14
DAY OUTLOOKS OF TEMPERATURE AND PRECIPITATION PROBABILITY,
VALID AS OF LATE WEDNESDAY AFTERNOON OF THE USDM RELEASE
WEEK. THE NWS FORECAST WEB PAGE USED FOR THIS SECTION IS:
HTTP://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/FORECASTS/. DURING THE
PAST 7 DAYS, DRYNESS GENERALLY DECREASED EAST OF THE MISSISSIPPI
RIVER IN ASSOCIATION WITH MULTIPLE LOW-PRESSURE SYSTEMS
THAT MOVED ACROSS THE REGION FROM MARCH 10-14. HEAVY RAINS
LINKED TO FLOODING WERE OBSERVED FROM THE OHIO RIVER VALLEY
TO NEW ENGLAND. OUT WEST, THE PATTERN OF CONTINUED DRY
CONDITIONS ACROSS THE NORTHERN ROCKIES CONTINUED. MOST OF THE
PRECIPITATION FROM THE LONE STORM SYSTEM THAT IMPACTED THE
NORTHWEST FELL WEST OF THE CASCADES. LIGHT RAINS PRECLUDED
ANY EXPANSION OF DRYNESS IN TEXAS BUT DID NOT AMOUNT TO ENOUGH
TO COMPLETELY ALLEVIATE LONGER TERM DRYNESS. EAST OF THE
MISSISSIPPI RIVER: MANY AREAS EAST OF THE MISSISSIPPI RIVER
VALLEY RECEIVED SOME PRECIPITATION OVER THE PAST WEEK, WITH SOME
AREAS RECORDING DEVASTATING FLOODING. NOTABLE AREAS RECEIVING
LITTLE TO NO PRECIPITATION WERE THE ALREADY PRESENT DROUGHT
AREAS IN THE UPPER MIDWEST AND OVER THE SOUTHERN INDIANA TO
CENTRAL KENTUCKY. THE ABNORMALLY DRY /D0/ AND MODERATE DROUGHT
/D1/ AREAS IN NORTHERN WISCONSIN WERE RESHAPED TO REFLECT THE
ISOLATED REPORTS OF GREATER THAN 1.0 INCH OF RAIN ACROSS FOREST,
MARINETTE, LANGLADE AND OCONTO COUNTIES. A SMALL ADJUSTMENT
WAS MADE IN THE IN VICINITY OF OCEANA AND MASON COUNTIES IN
MICHIGAN TO REFLECT RECENT PRECIPITATION AND BETTER ALIGN WITH
3- AND 6-MONTH STANDARDIZED PRECIPITATION INDEX /SPI/ VALUES.
PRECIPITATION OVER THE PAST WEEK BYPASSED MOST OF WESTERN
KENTUCKY AND SOUTHERN INDIANA BUT RAINS ACROSS WESTERN AND
CENTRAL TENNESSEE RANGED FROM 0.5-2.5 INCHES. SOIL MOISTURE
VALUES FROM THE UNIVERSITY OF WASHINGTON MODELS SHOW THE DRIEST
SOILS /BELOW THE TENTH PERCENTILE/ OVER WESTERN AND CENTRAL
KENTUCKY, RESPONDING WELL TO THE RAINS ACROSS TENNESSEE. TEXAS:
THE AREAS OF ABNORMAL DRYNESS IN SOUTHERN AND WESTERN TEXAS
PERSISTED, WITH LITTLE PRECIPITATION REPORTED IN THESE REGIONS
DURING THE PAST 7 DAYS. THE WEST: PRECIPITATION ACROSS THE WEST
WAS SCATTERED IN COVERAGE AT BEST, WITH THE HIGHEST AMOUNTS
ALONG THE COASTS OF OREGON AND WASHINGTON /1.0 TO GREATER
THAN 5.0 INCHES/ AND IN THE SIERRA NEVADA /0.5-2.0 INCHES/.
MOST OF THE PRECIPITATION FELL OUTSIDE OF THE MODERATE AND
SEVERE DROUGHT AREAS, SO MOST OF THE CHANGES TO THE DROUGHT
MONITOR WERE SMALL IN SCALE. IN NORTHEAST WASHINGTON,
SOME ABNORMAL DRYNESS WAS ALLEVIATED DUE TO 1.0-2.2 INCHES OF
RAINFALL. ACROSS THE NORTHERN ROCKIES IN IDAHO AND MONTANA,
LOCAL INPUTS COMBINED WITH AVAILABLE NATIONAL LEVEL DATA TO
DRIVE SOME MODEST IMPROVEMENTS. THE AREA OF EXTREME DROUGHT
IN WESTERN MONTANA WAS TRIMMED BACK DUE TO REPORTS OF 0.5
1.0 INCH OF PRECIPITATION JUST EAST OF MONTANA-IDAHO BORDER.
IN WESTERN WYOMING, SEVERE DROUGHT COVERAGE WAS EXPANDED BASED
ON CONTINUED BELOW-AVERAGE SNOW WATER EQUIVALENCE MEASUREMENTS
/MANY SITES IN THE LOWEST 5 PERCENT ACCORDING TO THE NATURAL
RESOURCES CONSERVATION SERVICE/. BESIDES THE LOW WATER CONTENT,
PRECIPITATION CONTINUED TO BE BELOW NORMAL IN THE ALREADY DRY
AREAS, SO THAT PROMPTED AN INTENSIFICATION OF THE MOST SEVERE
DROUGHT, RATHER THAN AN OVERALL EXPANSION. SURFACE WATER SUPPLY
INDEX /SWSI/ AND SPI3 AND SPI6 VALUES INDICATED SEVERE DROUGHT
ACROSS NORTHWESTERN COLORADO, BUT LOCAL INFORMATION SUGGESTED
THAT CONDITIONS WERE NOT AS DRY AS THOSE TWO MEASUREMENTS
INDICATED. SOIL MOISTURE VALUES CPC INDICATE NEAR NORMAL
CONDITIONS AND RESERVOIRS ARE IN GOOD SHAPE, SO THE SNOWPACK
AND LOW DEMAND SEEM TO BE MITIGATING THE LACK OF PRECIPITATION.
MODERATE DROUGHT WAS INTRODUCE FROM GRAND TO MOFFAT COUNTIES
IN NORTHERN COLORADO TO REFLECT THE WORSENING CONDITIONS, BUT
HOLDING SHORT OF RELYING COMPLETELY ON MODELED DATA IN FAVOR
OF OBSERVATIONS. ACROSS THE SOUTHERN ROCKIES, IMPROVEMENTS
WERE MADE ACROSS SOUTHERN UTAH, BASED ON ABOVE-AVERAGE SNOWPACK
/110-150 PERCENT OF NORMAL/ AT SNOTEL SITES AND LOCAL INPUTS.
ADDITIONALLY, SWSI VALUES FOR THE MOAB AND VIRGIN RIVER BASINS
IN SOUTHERN UTAH INDICATE ABOVE-NORMAL WATER SUPPLIES, WITH
SWSI VALUES OF 1.74 AND 2.78 RESPECTIVELY. CONSISTENT WITH
IMPROVED CONDITIONS IN SOUTHERN UTAH, SOME IMPROVEMENTS WERE
MADE IN SOUTHERN NEVADA AS WELL. SPI6 AND SPI12 BOTH INDICATE
SEVER DROUGHT, BUT SPI VALUES AT OTHER TIMESCALES LESS THAN
1 YEAR SUPPORT ONLY MODERATE DROUGHT /D1/. MODELED SOIL
MOISTURE VALUES SHOW NEAR-NORMAL OR EVEN WETTER THAN NORMAL
CONDITIONS WITH MONTHLY PRECIPITATION BEING NEAR NORMAL.
MINOR IMPROVEMENTS WERE MADE ACROSS CENTRAL ARIZONA IN RESPONSE
TO THE WET WINTER. IN NORTHERN CALIFORNIA, MODERATE DROUGHT
CONDITIONS WERE REMOVED FROM MOST OF TEHAMA COUNTY, REFLECTING
POSITIVE SPI VALUES /MEASURED AT THREE MONTH INTERVALS OUT
TO 1 YEAR/, SOIL MOISTURE VALUES FROM MULTIPLE MODELS, AND A
LACK OF REPORTED IMPACTS. PRECIPITATION DEFICITS AT 30 AND
90 DAYS DO STILL EXISTS, SO THE AREA OF D1 WAS NOT REMOVED
COMPLETELY. ALONG THE EASTERN BORDER OF CALIFORNIA, THE AREA OF
EXTREME DROUGHT /D2/ WAS EXTENDED SOUTHWARD TO PLUMAS COUNTY,
SUPPORTED BY CLIMATE PREDICTION CENTER /CPC/ SOIL MOISTURE
VALUES AND RESERVOIR LEVELS AT OROVILLE RESERVOIR. WITH
STORAGE AT 57 PERCENT OF THEIR HISTORICAL AVERAGE FOR MARCH
16, OROVILLE RESERVOIR IS THE LEAST FULL, WHEN COMPARED TO
ITS HISTORICAL AVERAGE, OF ALL THE MAJOR RESERVOIRS ACCORDING
TO THE CALIFORNIA DEPARTMENT OF WATER RESOURCES. FINALLY,
PRECIPITATION AND SNOWPACK HAVE BEEN BELOW AVERAGE FOR A WHILE
ACROSS IDAHO, MONTANA, AND WESTERN WYOMING, AND HAVE DECLINED TO
SERIOUSLY LOW LEVELS RECENTLY. AS A RESULT, D1 AND D2 CONDITIONS
EXPANDED SIGNIFICANTLY ACROSS THESE REGIONS AND ADJACENT EASTERN
WASHINGTON AND OREGON. IN THE WESTERN HALF OF WYOMING, SNOWPACK
WATER CONTENT WAS GENERALLY BELOW 70 PERCENT OF AVERAGE FOR
THE DATE, AND SURFACE WATER SUPPLY INDICES /SWSIS/ WERE AMONG
THE LOWEST 5 TO 20 PERCENT OF EXPECTED VALUES FOR THIS TIME
OF YEAR. IN AREAS OF WESTERN WYOMING AND ADJACENT UTAH WHERE
SNOWPACK WATER CONTENT WAS BELOW 55 PERCENT OF NORMAL FOR THE
DATE, D2 WAS INTRODUCED. FARTHER NORTH, SIGNIFICANT D1 AND D2
EXPANSION TOOK PLACE ACROSS CENTRAL AND NORTHERN IDAHO AND,
TO A LESSER EXTENT, WESTERN WYOMING AS SEASONAL PRECIPITATION
TOTALS AND SNOWPACK WATER CONTENT CONTINUED TO DECLINE RELATIVE
TO AVERAGE CONDITIONS FOR EARLY MARCH. DURING THE LAST 60 DAYS,
LESS THAN HALF OF NORMAL PRECIPITATION FELL ON NORTHWESTERN
MONTANA AND ESSENTIALLY THE NORTHERN HALF OF IDAHO. HAWAII AND
ALASKA: THE WINDWARD /NORTHEAST/ FACING SLOPES OF HAWAII SAW
MINOR IMPROVEMENTS DUE TO FREQUENT TRADE WIND SHOWER ACTIVITY.
ABNORMAL DRYNESS WAS REMOVED FROM THE EAST AND NORTHEAST
SLOPES OF THE BIG ISLAND AND THE NORTHEAST SLOPES OF OAHU.
SEVERE DROUGHT /D2/ WAS SHIFTED FROM NORTHEAST KAUAI TO THE
SOUTHEAST PORTION OF THE ISLAND. RAINFALL ELSEWHERE WAS
WELCOME, BUT DID LITTLE TO IMPACT THE DROUGHT CONDITIONS.
IN ALASKA, THE WEST SIDE OF THE SUSITNA BASIN HAS RECEIVED
APPROXIMATELY 80 PERCENT OF AVERAGE SNOWFALL, THE TOK SNOW
COURSE RECEIVED 90 PERCENT OF AVERAGE, AND THE 40 MILE SNOW
COURSES AND PORCUPINE BASIN SNOW COURSES WERE 88 AND 87 PERCENT
OF AVERAGE, RESPECTIVELY. DRYNESS DID CONTINUE FOR PORTIONS OF
THE STATE, WITH THE RED DOG MINE PRECIPITATION GAUGE CATCHING
ONLY 39 PERCENT OF AVERAGE SINCE OCT. 1. THE GULF COAST AND
SOUTHEAST WERE DRY IN FEBRUARY, BUT HAVE RECEIVED SIGNIFICANT
PRECIPITATION THE FIRST 2 WEEKS OF MARCH. THEY HAVE RECEIVED
AVERAGE OR MORE FOR THE MONTH. ADDITIONAL, BETTLES AND HOMER
REPORTED ABOVE-NORMAL PRECIPITATION, SO THE AREA OF ABNORMAL
DRYNESS WAS TRIMMED ON THE NORTH AND SOUTH, WHILE EXPANDING
WESTWARD. LOOKING AHEAD: MODERATE TO ISOLATED POCKETS OF HEAVY
PRECIPITATION ARE ANTICIPATED FROM MARCH 17-22, 2010 ACROSS
PORTIONS OF THE NORTHERN AND CENTRAL ROCKIES, GREAT PLAINS,
UPPER MIDWEST, GREAT LAKES, AND SOUTHEAST. LIGHT PRECIPITATION
IS FORECAST FOR MOST OF THE COUNTRY EAST OF THE ROCKIES,
WITH MOST OF THE PRECIPITATION FORECAST TO FALL OUTSIDE OF
THE CURRENTLY DEPICTED DROUGHT AREAS. FOR THE ENSUING 5 DAYS
/MARCH 23-27, 2010/, THE ODDS FAVOR DRIER THAN NORMAL CONDITIONS
ACROSS MUCH OF THE CONTIGUOUS 48 STATES. WETTER THAN NORMAL
CONDITIONS ARE FAVORED ALONG THE GULF COAST, EASTERN SEABOARD
AND LOWER GREAT LAKES. SOUTHERN ALASKA SHOULD CONTINUE TO BE
WET, AT ODDS WITH THE INTERIOR AND NORTHERN PORTIONS OF THE
LARGEST STATE, WHICH SHOULD BE DRIER THAN AVERAGE.
AUTHOR: MATTHEW ROSENCRANS, NOAA/NWS/NCEP/CLIMATE PREDICTION
CENTER.
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.
$$
