770
FXUS07 KWBC 311905
PMD30D
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EST THU JAN 31 2008
30-DAY OUTLOOK DISCUSSION FOR FEBRUARY 2008
SSTS IN THE CENTRAL AND EASTERN PACIFIC REMAIN WELL BELOW NORMAL AS LA NINA
CONDITIONS CONTINUE. THE TWO MOST RECENT WEEKLY TEMPERATURE ANOMALIES FOR THE
NINO 3.4 REGION ARE MORE THAN 2 DEGREES CELSIUS BELOW NORMAL INDICATING A
STRENGTHENING LA NINA. THE CFS FORECAST IS FOR MONTHLY MEAN NINO 3.4
TEMPERATURE ANOMALIES TO BE BETWEEN -1.5 AND -2.0 C FOR THE NEXT SEVERAL
MONTHS. THE MOST RECENT 40 CFS ENSEMBLE MEMBERS USING INITIAL CONDITIONS FROM
JANUARY 21 TO 30 INDICATE ABOVE NORMAL MEAN TEMPERATURES FOR FEBRUARY FOR MOST
OF THE U.S. EAST OF THE ROCKIES AND BELOW NORMAL MEAN TEMPERATURES FOR THE
PACIFIC COASTAL STATES AND THE ALASKAN PANHANDLE. THIS GENERAL PATTERN OF COLD
IN THE WEST AND WARM IN THE EAST IS CONSISTENT WITH THE EXTENDED RANGE OUTLOOK
BASED ON THE GFS AND ECMWF ENSEMBLES AND HIGH RESOLUTION MODEL SIMULATIONS FOR
THE NEXT TWO WEEKS AND SIMILAR TO COMPOSITES OF STRONG LA NINA ANALOGS. THE
UPDATE FOR THE MONTHLY OUTLOOK HAS AN ENHANCED LIKELIHOOD OF BELOW NORMAL
TEMPERATURES ALONG THE WEST COAST AND GREATER PROBABILITY OF ABOVE NORMAL
TEMPERATURES IN THE SOUTHEAST. THE UPDATE TO THE MONTHLY OUTLOOK FOR
PRECIPITATION HAS CHANGED ONLY SLIGHTLY FROM THE INITIAL FORECAST. BASED ON THE
MOST RECENT CFS ENSEMBLE MEMBERS AND THE RECENT GFS AND ECMWF MODEL SIMULATIONS
FOR THE NEXT TWO WEEKS, THERE IS AN ENHANCED CHANCE FOR ABOVE NORMAL
PRECIPITATION IN NEW ENGLAND AND PARTS OF THE SOUTHEAST AND AN INCREASED
PROBABILITY OF BELOW NORMAL PRECIPITATION IN THE SOUTHERN PLAINS INCLUDING
TEXAS COMPARED TO THE INITIAL MONTHLY OUTLOOK.
FOLLOWING IS THE TEXT FROM THE 30-DAY OUTLOOK DISCUSSION RELEASED JANUARY 17,
2008:
SSTS IN THE EASTERN EQUATORIAL PACIFIC ARE WELL BELOW NORMAL INDICATING RATHER
STRONG LA NINA CONDITIONS. SSTS IN THE PACIFIC HAVE BEEN CONSISTENTLY BELOW
NORMAL ALONG THE EQUATOR IN THE PAST SEVERAL WEEKS, WITH SST ANOMALIES NOW MORE
THAN 1 DEGREE C BELOW NORMAL FROM AROUND 165E TO THE SOUTH AMERICAN COAST WITH
ANOMALIES OF -2 C FROM THE DATE LINE TO 110W. OCEAN TEMPERATURES IN THE UPPER
200 M OF THE EASTERN PACIFIC REMAIN WELL BELOW NORMAL, SUGGESTING THAT SST
ANOMALIES WILL PERSIST NEAR THEIR CURRENT LEVELS INTO FEBRUARY. CONSISTENT WITH
LA NINA CONDITIONS, THE LOW-LEVEL EASTERLY WINDS HAVE BEEN STRONGER THAN NORMAL
OVER THE CENTRAL TROPICAL PACIFIC MODULATED BY THE RECENT MADDEN-JULIAN
OSCILLATION (MJO) IN DECEMBER AND EARLY JANUARY, AND CONVECTION HAS BEEN
SUPPRESSED OVER MUCH OF THE CENTRAL EQUATORIAL PACIFIC. THE EASTWARD
PROGRESSION OF ENHANCED CONVECTIVE ACTIVITY APPEARS TO HAVE STALLED OVER THE
WESTERN PACIFIC OCEAN, SO LA NINA CONDITIONS ARE EXPECTED TO DOMINATE NEAR TERM
SEASONAL VARIABILITY. OCEANIC AND ATMOSPHERIC CONDITIONS REFLECT A RELATIVELY
STRONG LA NINA EVENT.
LA NINA CONDITIONS ARE EXPECTED TO HAVE THE GREATEST IMPACT ON U.S. TEMPERATURE
AND PRECIPITATION IN FEBRUARY RELATIVE TO PREVIOUS MONTHS AND LA NINA
CONDITIONS IN DECEMBER APPEAR AT THEIR STRONGEST SO FAR FOR THIS EVENT. THE
TEMPERATURE OUTLOOK IS LARGELY BASED ON TREND ADJUSTED JFM LA NINA COMPOSITES
AND FEBRUARY LA NINA COMPOSITES BASED ON THE CURRENT NINO 3.4 SST ANOMALIES,
WHICH INDICATE AN ENHANCED PROBABILITY OF ABOVE NORMAL OVER MOST OF THE U.S.
WITH THE EXCEPTION OF THE NORTHERN TIER FROM THE PACIFIC NORTHWEST TO THE
NORTHERN PLAINS, WHERE AN ENHANCED PROBABILITY OF BELOW NORMAL IS SHOWN FOR THE
REGION WHERE COMPOSITE ANOMALIES ARE MOST NEGATIVE. PROBABILITIES ACROSS THE
U.S. ARE ADJUSTED SLIGHTLY TO CONSIDER CURRENT CONDITIONS INCLUDING SNOW COVER.
THE CCA, SMLR, OCN AND CFS TOOLS GENERALLY AGREE WITH THE LA NINA COMPOSITES.
BELOW NORMAL SST ALONG THE U.S. PACIFIC COAST SHOULD PERSIST THROUGH THE MONTH
OF FEBRUARY PRODUCING HIGHER CHANCES FOR BELOW NORMAL TEMPERATURE ALONG THE
SOUTHERN CALIFORNIA COAST.
THE PRECIPITATION FORECAST FOR FEBRUARY ALSO LARGELY REFLECTS LA NINA
COMPOSITES, WHICH INDICATE MEAN DRY CONDITIONS ACROSS THE SOUTHERN U.S. AND
MEAN WET CONDITIONS PRIMARILY IN TWO AREAS OF THE NORTHERN U.S.: THE PACIFIC
NORTHWEST AND FROM THE OHIO AND TENNESSEE VALLEY NORTHWARD INTO THE GREAT LAKES
REGION. THE PROBABILITY OF BELOW NORMAL PRECIPITATION IN THE SOUTHEAST HAS BEEN
REDUCED DUE TO RECENT ATMOSPHERIC CIRCULATION AND PRECIPITATION PATTERNS. THE
FLORIDA PENINSULA CONTINUES TO HAVE THE GREATEST PROBABILITY FOR BELOW NORMAL
PRECIPITATION.
FORECASTER: DAN COLLINS
NOTES: AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL
PROBABILITIES) ARE NOW LABELED AS EC (EQUAL CHANCES).
THE NEXT MONTHLY OUTLOOK...FOR MARCH 2008...WILL BE ISSUED ON THU FEB 21 2008
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1971-2000 BASE PERIOD.
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