100
FXUS25 KWNC 211230
PMDDRO
US DROUGHT MONITOR DISCUSSION
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
830 AM EST THU 21 MAY 2009
NATIONAL DROUGHT SUMMARY MAY 19, 2009 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 MAY
12-18, VERY WET AND STORMY CONDITIONS PREVAILED OVER THE EASTERN
HALF OF THE COUNTRY. A SLOW MOVING FRONTAL SYSTEM TRACKED
ACROSS THE CENTRAL STATES EARLY IN THE PERIOD AND THE EASTERN
STATES LATER IN THE PERIOD. THE HEAVIEST AMOUNTS OF RAIN FELL
FROM EASTERN OKLAHOMA NORTHEASTWARD TO THE OHIO RIVER VALLEY,
ON PARTS OF NEW YORK AND PENNSYLVANIA, AND ALSO ACROSS PARTS OF
THE SOUTHEAST. THE SOUTHERN END OF THE COLD FRONT BROUGHT SOME
PRECIPITATION /UP TO 2 INCHES/ ACROSS CENTRAL TEXAS, BRINGING
MODEST IMPROVEMENT TO THE REGION. LATE IN THE PERIOD, AN AREA
OF LOW PRESSURE ALOFT AND A STATIONARY FRONT BROUGHT AS MUCH
AS 5 TO 10 INCHES OF RAIN TO NORTHEAST FLORIDA, AND SIGNIFICANT
AMOUNTS ACROSS MOST OF THE STATE. OVER THE SOUTHWEST, LITTLE TO
NO PRECIPITATION AND UNSEASONABLY HOT TEMPERATURES DOMINATED
DURING THE PERIOD. WEEKLY AVERAGE TEMPERATURES RANGED FROM
6 TO 10 DEGREES F ABOVE NORMAL, WITH HIGHS IN THE TRIPLE
DIGITS AS FAR NORTH AS NORTHERN CALIFORNIA. NORTHEAST AND
MID-ATLANTIC, AND CAROLINAS: TWO TO FOUR INCHES OF RAIN
FELL ACROSS NORTHEAST PENNSYLVANIA AND SOUTHERN NEW YORK,
ALLEVIATING MOST OF THE D0 IN THE NORTHEAST. D0/H/ REMAINED
WHERE LOWER PRECIPITATION AMOUNTS WERE REPORTED /LESS THAN
AN INCH/, AND YEAR-TO-DATE PRECIPITATION AMOUNTS WERE 50 TO
75 PERCENT OF NORMAL. AVERAGE USGS STREAM FLOWS FOR LATEST
7, 14, AND 28 DAYS WERE STILL IN THE LOWER 25TH PERCENTILE
OVER NORTHWEST PENNSYLVANIA AND WESTERN NEW YORK. IN THE
CAROLINAS, ANOTHER WEEK OF MODERATE TO HEAVY /2-4 INCHES/
RAINFALL IN THE DROUGHT AREAS FURTHER DIMINISHED D0/H/ IN
WESTERN AND EASTERN NORTH CAROLINA, AND WESTERN SOUTH CAROLINA.
REPORTS FROM THE GEORGIA STATE CLIMATOLOGIST INDICATED THAT
LAKE LANIER WAS STILL 6 FEET BELOW NORMAL SUPPORTING D0/H/ IN
NORTHEAST GEORGIA. IN EASTERN NORTH CAROLINA AND THE SOUTHERN
APPALACHIANS, MEASURED PRECIPITATION WAS A FOOT BELOW NORMAL
FOR THE PAST 12 MONTHS, AND LONG-TERM BLENDS SUPPORTED THE
CONTINUATION OF THE DROUGHT. FLORIDA: AFTER A VERY DRY
SPRING, THE SOUTH FLORIDA WET SEASON BEGAN 9 DAYS EARLY, ON
MAY 11. WIDESPREAD SHOWERS AND THUNDERSTORMS COVERED MOST OF
THE STATE, BRINGING AT LEAST 1 INCH OF RAIN TO THE DROUGHT
AREA. ONE TO TWO CATEGORY IMPROVEMENTS WERE MADE FROM FORT
MYERS TO TAMPA TO THE I-4 CORRIDOR TO PALM COAST, WHERE 4 TO
LOCALLY 10 INCHES OF RAIN FELL. SOUTH OF LAKE OKEECHOBEE, 2
TO LOCALLY 6 INCHES OF RAIN REDUCED DROUGHT BY A CATEGORY. THE
KBDI GREATLY IMPROVED, DROPPING FROM 600-800 BEFORE THE ONSET
OF PRECIPITATION TO 100-300 ON MAY 19. AVERAGE STREAM FLOW
VALUES IMPROVED ACCORDINGLY. DESPITE THE RECENT WET WEATHER,
LOWER RAINFALL /1-2 INCHES/ DID NOT SIGNIFICANTLY MITIGATE
THE DROUGHT FROM LAKE OKEECHOBEE NORTHWARD TO BREVARD COUNTY,
AND D3 REMAINED. AS OF MAY 19, LAKE OKEECHOBEE WAS AT 10.6 FEET
/2.64 FEET BELOW NORMAL/, FINALLY RISING AFTER DROPPING SINCE
MID-SEPTEMBER 2008. HEAVY RAINS FELL AFTER THE 12 UTC MAY
19 DATA CUTOFF, AND FURTHER IMPROVEMENT WILL LIKELY BE SHOWN
NEXT WEEK. MIDWEST: LIGHT TO MODERATE RAINS FELL ON THE UPPER
MIDWEST, WITH THE HEAVIER AMOUNTS /BETWEEN 1.0 AND 1.5 INCHES/
OCCURRING IN EASTERN WISCONSIN, THE UPPER PENINSULA OF MICHIGAN,
AND NORTHERN LOWER MICHIGAN. THE RAINS WERE ENOUGH TO ALLEVIATE
ABNORMAL DRYNESS IN THOSE THREE AREAS, BUT FURTHER WEST,
LARGER DEFICIENCIES REMAINED. AT 30-, 60-, 90-, AND 180-DAYS,
PRECIPITATION WAS STILL LESS THAN 70 PERCENT OF NORMAL. WEEKLY
RAINFALL AMOUNTS WERE LESS THAN 0.5 INCHES AS THE 7-, 14-, AND
28-DAY AVERAGE STREAM FLOWS REMAINED IN THE LOWEST QUARTILE.
THE D2 REGION WAS SHIFTED SOUTHWESTWARD TO BETTER DEPICT THE
DRIEST AREA. THE PLAINS: ALTHOUGH AN INCH OF RAIN FELL ON
EXTREME EASTERN NEBRASKA, DRIER CONDITIONS TO THE WEST EXPANDED
THE INITIAL D0 AREA IN NEBRASKA INTO SOUTHEASTERN SOUTH DAKOTA
AND NORTH-CENTRAL KANSAS. YEAR-TO-DATE DEFICITS EXCEEDED 6
INCHES IN THIS REGION, ALTHOUGH LONG-TERM /SUBSOIL/ MOISTURE
SUPPLIES WERE ADEQUATE. IMPACTS WERE NEGLIGIBLE AS THE DRIER
TOP SOILS ALLOWED PRODUCERS TO MAKE EXCELLENT PLANTING PROGRESS.
TOWARD THE END OF THE WEEK, HOT WEATHER /HIGHS NEAR 100 DEGREES
F/ ACCOMPANIED THE DRYNESS, RAISING CONCERNS OF ADDITIONAL D0
IN THE WESTERN CORN BELT. IN THE SOUTHERN PLAINS, A COLD FRONT
PRODUCED SCATTERED SHOWERS AND THUNDERSTORMS, SOME LOCALLY
HEAVY, OVER SOUTHWESTERN OKLAHOMA AND THE EASTERN TWO-THIRDS
OF TEXAS, INCLUDING FAR SOUTHERN TEXAS. IN OKLAHOMA, ROGER
MILLS COUNTY FINALLY RECEIVED DECENT RAINS /1.26 INCHES/ AFTER
MISSING OUT THE PAST FEW WEEKS, IMPROVING CONDITIONS THERE. THE
SPI BLEND PRODUCTS FROM TEXAS A&M SUPPORTED MORE IMPROVEMENT
ALONG THE RED RIVER, SOUTH-CENTRAL TEXAS, AND THE BIG BEND AREA.
IN THE RED RIVER REGION /DONLEY TO MONTAGUE COUNTIES/ 1 TO 2
INCHES OF RAIN PROVIDED ADDITIONAL RELIEF FROM THE DROUGHT. IN
SOUTH-CENTRAL TEXAS /WEBB TO GONZALES COUNTIES/, A CONVECTIVE
LINE DROPPED 1.5 TO 3 INCHES OF RAIN, PROMPTING IMPROVEMENT
ACROSS THE FORMER D4 REGION. ONE TO 1.5 INCHES OF RAIN ALSO
EASED DROUGHT IN STARR AND ZAPATA COUNTIES /NEAR LAREDO/.
IN THE BIG BEND AREA /PECOS, BREWSTER, AND TERRELL COUNTIES/
1 TO 1.5 INCHES OF RAIN ALLEVIATED ABNORMAL DRYNESS THERE.
IN CONTRAST, A ONE-CATEGORY DEGRADATION WAS MADE IN THE
TEXAS PANHANDLE /PARMER TO GARZA COUNTIES/ AS DRY AND HOT
WEATHER OCCURRED DURING THE NORMALLY WETTEST TIME OF THE YEAR.
A REASSESSMENT OF SPI VALUES SUGGESTED A WESTWARD SHIFT IN THE
CORE D2-D3 AREA IN NORTH-CENTRAL TEXAS /CENTERED OVER HASKELL
AND STONEWALL COUNTIES/. THE WORST OF THE D4 AREA WAS CENTERED
OVER ARANSAS COUNTY WHERE THE ARANSAS COUNTY AIRPORT REPORTED
14 PERCENT OF NORMAL PRECIPITATION OVER THE PAST 9 MONTHS /3.43
INCHES VERSUS 25.07 INCHES NORMALLY/. SINCE MARCH 26 OF 2009,
THE AIRPORT ONLY MEASURED 0.03 INCHES OF RAIN, OR 0.7 PERCENT
OF NORMAL! SINCE OCTOBER 1, 2007, A TOTAL OF 19 MONTHS, NOT
COUNTING THIS MAY, ARANSAS COUNTY AIRPORT HAS REPORTED ONLY
4 MONTHS WITH AT LEAST 50 PERCENT OF NORMAL PRECIPITATION.
IN NEW MEXICO, CONTINUED HOT AND MOSTLY DRY WEATHER FURTHER
DETERIORATED CONDITIONS. HIGHS REACHED THE CENTURY MARK IN MANY
LOCATIONS, AND TEMPERATURES AVERAGED 4 TO 8 DEGREES F ABOVE
NORMAL. ACCORDING TO THE NRCS, PRECIPITATION WAS WELL BELOW
NORMAL SINCE JANUARY ACROSS THE SOUTHERN THIRD OF THE STATE.
AS OF MAY 17, 92 PERCENT OF THE STATES TOP SOIL MOISTURE,
62 PERCENT OF THE TOTAL WINTER WHEAT, AND 65 PERCENT OF THE
PASTURES AND RANGES WERE RATED POOR OR VERY POOR, RESPECTIVELY,
BY NASS/USDA. ACCORDINGLY, AN EXPANSION OF D1 AND D2 WAS
MADE IN SOUTHEASTERN NEW MEXICO. THE WEST: AN EXPANSION OF
THE D1/A/ WAS MADE IN ARIZONA, BASED ON SHORT-TERM BLENDS,
14-,30-, AND 60-DAY PRECIPITATION TOTALS, WHICH WERE 2,5, AND
25-50 PERCENT OF NORMAL, RESPECTIVELY. THE ARIZONA EXPANSION,
WHICH INCLUDED THE AREA BETWEEN PHOENIX AND FLAGSTAFF NORTH
TO THE COLORADO RIVER WAS ALSO BASED ON 90-, 180-, 360-DAY
PRECIPITATION DEFICITS /LESS THAN 25 PERCENT OF NORMAL AT 90
DAYS, LESS THAN 70 PERCENT OF NORMAL AT 6 AND 12 MONTHS/.
IN EASTERN UTAH /FERRON CREEK AND MOAB/, SWSI VALUES NEAR
-2.0 LED TO AN EXPANSION OF THE D0 AREA.
A SMALL REDUCTION OF THE D1 AREA IN SOUTHWESTERN IDAHO WAS
BASED ON THE SHORT- AND LONG-TERM DROUGHT BLENDS, AND WATER
YEAR-TO-DATE BASIN AVERAGE PRECIPITATION WHICH STOOD AT
110 PERCENT OF NORMAL. STREAM FLOWS ARE GENERALLY NEAR TO
SLIGHTLY ABOVE NORMAL IN THIS REGION. THE REST OF THE WEST
RECEIVED LITTLE IF ANY PRECIPITATION, BUT SINCE THAT IS NOT
UNUSUAL FOR THIS TIME OF THE YEAR, NO CHANGES WERE INDICATED.
HAWAII AND ALASKA: IN KAUAI, A LATE-SEASON COLD FRONT DROPPED
BETWEEN 0.25 AND 1.00 INCH OF RAIN ON SOME SPOTS, BUT NOTHING
ALONG THE SOUTHWEST /LEEWARD/ SIDE. AVERAGE STREAM FLOWS OUT
THROUGH 28 DAYS WERE IN THE LOWEST DECILE. ADDITIONALLY, A USDA
REPORT FROM THE ISLAND INDICATED THAT PASTURE CONDITIONS WERE
STARTING TO DRY OUT EARLIER THAN NORMAL FOR THIS TIME OF YEAR,
PROMPTING THE INTRODUCTION OF D0 THROUGHOUT KAUAI.ELSEWHERE,
LIGHT SCATTERED WINDWARD SHOWERS MAINTAINED CONDITIONS.
IN ALASKA, LIGHT SHOWERS /LESS THAN 0.5 INCH OF RAIN/ ON TOP OF
30- AND 90-DAY OBSERVED PRECIPITATION DEFICITS AT SITKA /3.3/7.0
INCHES/, JUNEAU /1.9/3.6 INCHES/, AND YAKUTAT /8.5/21.5 INCHES/
DID LITTLE TO ALLEVIATE ABNORMAL DRYNESS THROUGHOUT THE ALASKAN
PANHANDLE. THE EXCEPTION WAS NEAR KETCHIKAN, WHERE 1-3 INCHES OF
RAIN FELL. LOOKING AHEAD: DURING THE NEXT 5 DAYS /MAY 21-25/
A STATIONARY FRONT AND AN UPPER LOW WILL BRING HEAVY RAINS TO
PARTS OF FLORIDA. THIS LOW IS FORECAST TO MOVE WESTWARD INTO THE
GULF, ALLOWING FLORIDA TO DRY OUT WHILE SOAKING THE CENTRAL GULF
COAST BY THE WEEKEND. A PAIR OF COLD FRONTS WILL TRACK ACROSS
THE NORTHERN TIER OF STATES, PRODUCING LIGHT TO MODERATE RAINS,
WITH POSSIBLY 2-4 INCHES FROM WYOMING TO SOUTH DAKOTA. IN THE
FOUR CORNERS REGION, SCATTERED SHOWERS AND STORMS WILL MOVE
INTO THE AREA AND INCREASE IN INTENSITY AND COVERAGE. WARM AND
DRY CONDITIONS ARE FORECAST FOR THE PACIFIC COAST STATES.
THE CLIMATE PREDICTION CENTER 6-10 DAY FORECAST /MAY 26-30/
CALLS FOR ABOVE-NORMAL PRECIPITATION OVER THE GULF AND ATLANTIC
COASTAL STATES /INCLUDING FLORIDA/, AND FROM WESTERN TEXAS AND
NEW MEXICO NORTHWARD THROUGH COLORADO. SUBNORMAL PRECIPITATION
IS EXPECTED ACROSS THE NORTHWEST, GREAT BASIN, NORTHERN PLAINS
AND UPPER MIDWEST. WARMER THAN USUAL WEATHER IS FORECAST FOR
THE WESTERN THIRD OF THE NATION, WHILE SUBNORMAL READINGS ARE
PREDICTED FOR THE CENTRAL AND SOUTHEASTERN U.S.
AUTHORS: MATTHEW ROSENCRANS, DAVID MISKUS, AND ANTHONY ARTUSA,
CPC/NCEP/NWS/NOAA.
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.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page