249
FGUS71 KRNK 291319 CCA
ESFRNK
NCZ001>006-018>020-VAZ007-009>020-022>024-032>035-043>047-058-059-WVZ
042>045-051900-
HYDROLOGIC OUTLOOK
NATIONAL WEATHER SERVICE BLACKSBURG VA
915 AM EDT THU MAY 29 2008
..DROUGHT/WATER RESOURCES STATEMENT NUMBER 2008-11
..DROUGHT WORSENS IN NORTH CAROLINA
SUMMARY...
RAINFALL HAS BEEN GENERALLY DEFICIENT THE LAST TWO WEEKS...WORSENING
THE DROUGHT YET AGAIN PRIMARILY IN NORTH CAROLINA. THE DROUGHT BEGAN
A YEAR AGO WITH AN EXTREMELY DRY MAY 2007 AND WHAT LOOKS TO BE
ANOTHER DRIER THAN NORMAL MAY WILL ENSURE THAT IT CONTINUES FOR A
WHILE YET.
THE BLACKSBURG HSA COVERS 27 COUNTIES IN SOUTHWEST VIRGINIA...4 IN
EXTREME SOUTHEAST WEST VIRGINIA AND 9 IN NORTHWEST NORTH CAROLINA
AND INCLUDES PORTIONS OF THE FOLLOWING RIVER BASINS:
JAMES...ROANOKE...NEW...GREENBRIER...DAN...YADKIN...CLINCH AND
HOLSTON.
THE U.S. DROUGHT MONITOR (USDM)...
THE USDM ISSUED YESTERDAY AND REFLECTING CONDITIONS THROUGH 8 AM ON
MAY 27 SHOWS A RETURN OF D3 OR EXTREME DROUGHT TO THE FAR SOUTHERN
REACHES OF THE HSA. THIS INCLUDES PORTIONS OF ASHE...WILKES AND
YADKIN COUNTIES. SEVERE DROUGHT (D2) HAS ALSO BEEN EXPANDED
NORTHWARD TO COVER MOST OF THE NORTH CAROLINA COUNTIES IN
THE BLACKSBURG HSA. CONDITIONS IN VIRGINIA ARE UNCHANGED ON THE USDM
WITH D1...MODERATE DROUGHT...IN AND NEAR THE BLUE RIDGE MOUNTAINS
SOUTH OF ROANOKE AND A BROAD AREA OF D0 OR ABNORMALLY DRY CONDITIONS
OVER MUCH OF SOUTHWEST VIRGINIA. THE WEST VIRGINIA COUNTIES REMAIN
IN THE NORMAL OR WETTER CATEGORY.
IT SHOULD BE POINTED OUT THAT THE CATEGORIES ON THE DROUGHT
MONITOR ARE GENERALIZED AND THE LOCAL IMPACTS OF DROUGHT MAY BE MORE
OR LESS THAN WHAT IS DEPICTED ON THE MAP.
THE U.S. DROUGHT MONITOR IS A JOINT EFFORT OF THE U.S. DEPARTMENT OF
AGRICULTURE...THE NATIONAL DROUGHT MITIGATION CENTER...THE NATIONAL
WEATHER SERVICE AND THE NATIONAL CLIMATIC DATA CENTER. THE WEBSITE
FOR THE U.S. DROUGHT MONITOR IS HTTP://WWW.DROUGHT.UNL.EDU/DM.
THE CATEGORIES OF DROUGHT ARE EXPLAINED BELOW:
D0 IS THE LEAST INTENSE INDICATOR OF DROUGHT ON A SCALE THAT RANGES
FROM D0 THROUGH D4. IT IS BASICALLY A DROUGHT WATCH THAT INDICATES A
REGION GOING INTO OR COMING OUT OF DROUGHT.
D1 IS MODERATE DROUGHT...CONDITIONS THAT MAY BE ASSOCIATED WITH D1
INCLUDE SOME CROP DAMAGE...INCREASED FIRE RISK...FALLING RIVER...
STREAM...AND RESERVOIR LEVELS AND SOME WATER SHORTAGES.
D2 IS SEVERE DROUGHT...CROP OR PASTURE DAMAGE IS LIKELY. FIRE RISK IS
POTENTIALLY HIGH...ALONG WITH WATER SHORTAGES AND POSSIBLE WATER
RESTRICTIONS.
D3 IS EXTREME DROUGHT...MAJOR CROP AND PASTURE LOSSES AND WIDESPREAD
WATER SHORTAGES AND RESTRICTIONS.
D4 IS EXCEPTIONAL DROUGHT...WIDESPREAD CROP AND PASTURE LOSSES...
WATER SHORTAGES AND WATER EMERGENCIES. MAY BE THOUGHT OF AS THE
50-YEAR DROUGHT OR THE 2 PERCENT ANNUAL CHANCE OF OCCURRENCE.
THE CATEGORIES ARE BASED ON A NUMBER OF KEY INDICATORS: 1) PALMER
DROUGHT INDEX (PDSI) 2) CPC SOIL MOISTURE MODEL 3) USGS WEEKLY
STREAMFLOW PRECENTILES 4) THE STANDARDIZED PRECIPITATION INDEX AND
5) THE SATELLITE VEGETATION INDEX.
RECENT PRECIPITATION...
THE FIRST HALF OF MAY HAD NEAR TO ABOVE NORMAL RAINFALL DUE TO
EVENTS ON MAY 8-9 AND MAY 11-12. THE SECOND HALF OF MAY HAS BEEN
MUCH DRIER ACROSS THE AREA WITH THE RESULT THAT OVERALL MAY RAINFALL
WILL LIKELY BE BELOW NORMAL...ESPECIALLY IN THE WORST DROUGHT AREAS
OF NORTHWEST NORTH CAROLINA. MANY LOCATIONS IN THAT REGION HAVE HAD
LESS THAN HALF OF NORMAL MAY RAINFALL. FINAL MAY NUMBERS WILL BE
AVAILABLE IN THE NEXT DROUGHT STATEMENT.
LONGER TERM PRECIPITATION...(FROM NWS COOPERATIVE NETWORK)
MONTH OR SEASON PRECIPITATION NORMAL % OF NORMAL
APRIL 2008 4.95 3.72 133
MARCH 2008 3.42 4.14 83
WINTER 07-08 (DEC-FEB) 7.19 9.99 72
FALL 2007 (SEP-NOV) 8.49 10.51 81
SUMMER 2007 (JUN-AUG) 9.42 11.79 80
PALMER DROUGHT SEVERITY INDEX (PDSI)...
THE PALMER INDEX IS CALCULATED WEEKLY AND INDICATES THE RELATIVE
DRYNESS OR WETNESS AFFECTING AN AREA. THERE ARE SEVEN PDSI
CATEGORIES DEFINING WET AND DRY CONDITIONS AS SHOWN IN THE TABLE
BELOW:
-4.0 OR LESS - EXTREME DROUGHT
-3.0 TO -3.9 - SEVERE DROUGHT
-2.0 TO -2.9 - MODERATE DROUGHT
-1.9 TO +1.9 - NEAR NORMAL
+2.0 TO +2.9 - UNUSUAL MOIST SPELL
+3.0 TO +3.9 - VERY MOIST SPELL
+4.0 OR ABOVE - EXTREMELY MOIST
THE TABLE BELOW SHOWS THE MAY 24 2008 PDSI FOR THE SIX CLIMATE ZONES
WHICH COVER THE BLACKSBURG HSA. DROUGHT CONTINUES TO WORSEN IN THE
NORTH CAROLINA MOUNTAINS AND REMAINS WELL INTO THE SEVERE CATEGORY.
MODERATE DROUGHT EXISTS OVER THE SOUTHWEST VIRGINIA MOUNTAINS.
STATE CLIMATE ZONE PDSI PRECIP NEEDED
TO BRING PDSI TO -0.5
NC N. MOUNTAINS -3.38 9.06
NC N. PIEDMONT -1.19 2.61
VA W. PIEDMONT 0.01
VA CENT. MTNS. 0.88
VA SW MOUNTAINS -2.25 5.03
WV SOUTHERN 0.60
FOR DETAILS ON THE PDSI SEE THE CLIMATE PREDICTION CENTER WEBSITE:
HTTP://WWW.CPC.NCEP.NOAA.GOV
SOIL MOISTURE...
THE NWS CLIMATE PREDICTION CENTER SOIL MOISTURE MODEL IS
USED TO ESTIMATE SOIL MOISTURE IN THE TOP 4 TO 5 FEET USING RECENT
OBSERVED DATA VERSUS LONG-TERM NORMALS. LITTLE OR NO DEFICIT EXISTS
OVER SOUTHEAST WEST VIRGINIA AND WESTERN VIRGINIA WHILE NORTHWEST
NORTH CAROLINA CONTINUES TO RUN DEFICITS OF 1 TO 3 INCHES.
SEE HTTP://WWW.CPC.NCEP.NOAA.GOV/SOLIMST/W.SHTML FOR THE LATEST
SOIL MOISTURE MAPS FOR THE UNITED STATES.
RIVERS AND STREAMFLOW...
DUE TO THE VARIABILITY OF DAILY STREAMFLOWS LIMITING THEIR UTILITY
AS A DROUGHT ANALYSIS TOOL A NEW TABLE IS PRESENTED THIS WEEK. THIS
TABLE SHOWS 7-DAY AVERAGE STREAMFLOW PERCENTILE CLASSES FROM RIVER
BASINS IN THE UNITED STATES GEOLOGICAL SURVEY (USGS) NETWORK. THE
TABLE SHOWS THAT SEVERE HYDROLOGIC DROUGHT EXISTS IN MOST OF THE NEW
RIVER BASIN IN NORTH CAROLINA AND VIRGINIA AND IN THE YADKIN-PEE DEE
IN NORTH CAROLINA. BASINS NOT SHOWN IN THIS TABLE HAVE 7-DAY FLOWS
ABOVE THE 25TH PERCENTILE.
RIVER BASIN PERCENTILE HYDROLOGIC DROUGHT
CLASS CATEGORY
NEW (VA/NC) <5 SEVERE
UPPER ROANOKE 6-9 MODERATE
DAN-LOWER ROANOKE 10-24 BELOW NORMAL
YADKIN-PEE DEE <5 SEVERE
FOR ADDITIONAL INFORMATION ON THIS DATA AND FOR ON CURRENT AND
HISTORICAL STREAMFLOWS SEE THE USGS WEBSITE AT
HTTP://WATERDATA.USGS.GOV/WATERWATCH.
RESERVOIRS
MAJOR LAKE LEVELS HAVE CONTINUED TO IMPROVE OR REMAIN STEADY OVER
THE PAST SEVERAL WEEKS...WITH THE EXCEPTION OF W. KERR SCOTT
RESERVOIR
IN NORTH CAROLINA WHICH HAS BEGUN TO DECLINE DUE TO LOW INFLOWS.
RESERVOIR CURRENT POOL NORMAL POOL
SMITH MOUNTAIN LAKE VA 793.70 795
CLAYTOR LAKE VA 1843.12 1846
LAKE MOOMAW VA 1582.23 1582
PHILPOTT RESERVOIR 973.98 974
BLUESTONE LAKE WV 1410.77 1410
W. KERR SCOTT NC 1029.42 1030
IN ADDITION...THE CARVINS COVE RESERVOIR...A MAJOR SOURCE FOR ROANOKE
DRINKING WATER...IS ONLY 5.0 FEET BELOW THE SPILLWAY AND HAS RISEN
ABOUT SIX FEET IN RECENT WEEKS. SPRING HOLLOW RESERVOIR...WHICH
SERVES ROANOKE COUNTY...IS 4.8 FEET BELOW ITS SPILLWAY...AN
IMPROVEMENT OF NEARLY NINE FEET IN THE PAST MONTH.
IMPACTS...
FOR INFORMATION ON IMPACTS IN THE STATE OF NORTH CAROLINA PLEASE SEE
THE STATE DIVISION OF WATER RESOURCES WEBSITE:
HTTP://WWW.NCWATER.ORG/
FOR INFORMATION ON IMPACTS IN THE STATE OF VIRGINIA PLEASE SEE THE
STATE DEPARTMENT OF ENVIRONMENTAL QUALITY WEBSITE:
HTTP://WWW.DEQ.VIRGINIA.GOV/
OUTLOOK...
A FRONT WILL MOVE THROUGH THE AREA THIS WEEKEND WITH THE POSSIBILITY
OF SOME MODERATE RAINFALL RANGING FROM 0.25 INCH IN THE PIEDMONT TO
1.00 INCH IN THE NORTHWEST MOUNTAINS.
SEE THE NWS BLACKSBURG WEBSITE FOR LOCAL WEATHER FORECASTS OUT TO
SEVEN DAYS: HTTP://WWW.ERH.NOAA.GOV/RNK.
ACCORDING TO THE NWS CLIMATE PREDICTION CENTER DURING THE 6 TO 10
DAY OUTLOOK PERIOD FROM JUNE 3-7 AND THE 8 TO 14 DAY OUTLOOK THROUGH
JUNE 11 THE HIGHEST PROBABILITY IS FOR NEAR NORMAL PRECIPITATION.
TEMPERATURES ARE FORECAST TO BE ABOVE OR NEAR NORMAL WITH WEAK
RIDGING OVER THE SOUTHERN U.S.
SEE THE CPC WEBSITE FOR ALL LONG-RANGE WEATHER AND CLIMATE FORECASTS
BEYOND SEVEN DAYS: HTTP://WWW.CPC.NCEP.NOAA.GOV.
SEE THE NOAA DROUGHT INFORMATION PAGE FOR A COMPREHENSIVE LISTING OF
DROUGHT RELATED INFORMATION: HTTP://WWW.DROUGHT.NOAA.GOV.
ANOTHER HYDROLOGIC OUTLOOK ON THIS SITUATION WILL BE ISSUED ON OR
ABOUT JUNE 12 UNLESS CONDITIONS WARRANT AN EARLIER UPDATE.
THIS IS THE FINAL ISSUANCE OF THIS PRODUCT UNDER THE ESFRNK PRODUCT
IDENTIFIER. BEGINNING JUNE 10 2008 ALL DROUGHT STATEMENT WILL BE
ISSUED UNDER DGTRNK IDENTIFIER. PLEASE SEE THE RECENT PUBLIC
INFORMATION STATEMENT /PNSRNK/ FOR DETAILS ON THIS CHANGE.
CORRIGAN
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