PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300PM EST MONDAY JAN 31 2011

30-DAY OUTLOOK DISCUSSION FOR FEBRUARY 2011

BORDERLINE STRONG LA NINA CONDITIONS CONTINUE ACROSS THE TROPICAL PACIFIC 
OCEAN. THE LATEST SEA SURFACE TEMPERATURES (SSTS) NEAR THE EQUATOR IN THE 
EASTERN AND CENTRAL PACIFIC OCEAN ARE BETWEEN 1 AND 3 DEG C BELOW NORMAL FROM 
THE SOUTH AMERICAN COAST TO ABOUT 160 E LONGITUDE. BELOW NORMAL SSTS EXTEND 
FROM THE EQUATOR TO 20N AND 20S LATITUDE THROUGHOUT THE EASTERN PACIFIC. THE 
FOUR NINO SST INDICES CONTINUE TO EXHIBIT MINOR VARIATIONS, WITH THE LATEST 
WEEKLY DEPARTURES RANGING BETWEEN -1.4 C AND -1.8 C. SUBSURFACE OCEAN 
TEMPERATURES ARE BELOW NORMAL TO A DEPTH OF ABOUT 200 METERS ALONG THE EQUATOR 
EAST OF AROUND 160W. THIS IS CONSISTENT WITH A SHALLOWER-THAN-AVERAGE 
THERMOCLINE ACROSS THE CENTRAL AND EASTERN EQUATORIAL PACIFIC. THE LARGE SCALE 
ATMOSPHERIC CIRCULATION OVER THE TROPICAL PACIFIC OCEAN CONTINUES TO CLEARLY 
REFLECT MATURE LA NINA CONDITIONS. CONVECTION IS ENHANCED OVER INDONESIA, AND 
SUBSTANTIALLY REDUCED OVER THE WESTERN AND CENTRAL EQUATORIAL PACIFIC OCEAN. 
LOW LEVEL EASTERLY TRADE WINDS ARE ENHANCED, AS ARE WESTERLY WIND ANOMALIES AT 
UPPER LEVELS OVER THE WESTERN AND CENTRAL PACIFIC.

ALL NUMERICAL AND STATISTICAL ENSO FORECAST MODELS MAINTAIN SUBSTANTIALLY 
NEGATIVE SST ANOMALIES AT LEAST INTO BOREAL SPRING. THE MAJORITY OF DYNAMICAL 
MODEL MJO FORECASTS INDICATE ONLY MODEST MJO ACTIVITY AT BEST, WITH BACKGROUND 
LA NINA CONDITIONS EXPECTED TO DOMINATE THE PATTERN OF TROPICAL CONVECTION. THE 
SST ANOMALIES IN THE NINO 3.4 REGION ARE FORECAST TO AVERAGE SOMEWHERE BETWEEN 
-1 C AND -2 C THE REMAINDER OF THE WINTER SEASON, SUGGESTING MODERATE TO STRONG 
LA NINA CONDITIONS FOR FEBRUARY 2011.  FINALLY, THERE IS THE (N)AO TO CONSIDER, 
WHICH UNFORTUNATELY CANNOT BE RELIABLY PREDICTED MORE THAN ABOUT 2 WEEKS IN 
ADVANCE, BUT HAS BEEN STRONGLY NEGATIVE ALL WINTER AND IS PREDICTED TO BE 
NEGATIVE BY THE CFS EVEN IN FEBRUARY.

THE LONG LEAD FEBRUARY 2011 TEMPERATURE AND PRECIPITATION OUTLOOKS WAS BASED ON 
LA NINA COMPOSITES WITH CONSIDERATION OF OTHER TRADITIONAL STATISTICAL TOOLS, 
RECENT TEMPERATURE AND PRECIPITATION OBSERVATIONS, AND THE EXPECTATION THAT A 
SIGNIFICANT, NEGATIVE AO WILL PREVAIL THROUGH FEBRUARY. COVERAGE IS VERY HIGH 
FOR A MONTHLY FORECAST ALTHOUGH PROBABILITIES ARE MODEST.

THE UPDATE AT THE END OF THE MONTH CONSIDERS IN ADDITION TO THE ABOVE MENTIONED 
TOOLS ALSO NWP SOLUTIONS AVAILABLE ON JANUARY 31 FOR THE FIRST 10 DAYS OF 
FEBRUARY. WE SHOULD MAKE NOTE THAT THE AO HAS NOW GONE POSITIVE FOR THE FIRST 
TIME SINCE MID-NOVEMBER AND PREDICTED TO BE POSITIVE FOR AT LEAST ANOTHER 5 
DAYS. THIS IN AND OF ITSELF ARGUES FOR MORE CANONICAL LA NINA COMPOSITES, WHICH 
IS LESS COLD IN THE EAST THAT PREDICTED AT LONG-LEAD. ON THE OTHER HAND THE NWP 
SOLUTIONS FOR THE US SHOW EXTENSIVE COLD AT THE START OF THE MONTH. WE ONLY 
SLIGHTLY ADJUSTED THE 33% CHANCE OF BELOW NORMAL CONTOUR, MAINLY BY BRINGING IT 
FARTHER SOUTH IN THE ROCKY MOUNTAINS AND PULLING IT OUT OF THE SOUTHEAST. WE 
MADE FURTHER ADJUSTMENTS BASED ON RATHER HEAVY PRECIPITATION TO BE BROUGHT BY A 
MAJOR WINTERSTORM ON FEB 1 AND 2. SPECIFICALLY WE MOVED THE 33% LINE FOR ABOVE 
MEDIAN IN THE OHIO VALLEY FARTHER WEST, AND SHARPLY REDUCED THE PROBABILITIES 
FOR BELOW MEDIAN PRECIPITATION IN THE BORDER AREA OF FLORIDA, GEORGIA AND 
ALABAMA, GIVEN THAT MORE THAN 1.5 INCHES OF RAIN MAY FALL IN THAT AREA OVER THE 
NEXT FEW DAYS.


THE TEMPERATURE OUTLOOK FOR FEBRUARY 2011 CALLS FOR ENHANCED ODDS OF BELOW 
AVERAGE MEAN TEMPERATURES ALONG THE WEST COAST, IN THE PACIFIC NORTHWEST, 
ACROSS THE NORTHERN TIER OF STATES AND FROM THE SOUTHERN GREAT LAKES REGION 
SOUTHWARD AND EASTWARD INTO TENNESSEE. THERE ARE ENHANCED ODDS OF BELOW AVERAGE 
MEAN TEMPERATURES ALSO OVER MOST OF ALASKA, INCLUDING THE ENTIRE PANHANDLE 
REGION. ENHANCED ODDS FOR ABOVE NORMAL TEMPERATURE ARE EXPECTED ACROSS THE 
SOUTH FROM ARIZONA TO LOUISIANA, WITH THE HIGHEST PROBABILITIES IN TEXAS AND 
NEW MEXICO. ELSEWHERE, EQUAL CHANCES (EC) OF BELOW-, NEAR-, AND ABOVE-NORMAL 
MEAN TEMPERATURES ARE PREDICTED.

THE PRECIPITATION OUTLOOK FOR FEBRUARY 2011 CALLS FOR ELEVATED ODDS OF ABOVE 
MEDIAN PRECIPITATION ACROSS THE NORTHERN TIER OF STATES, INCLUDING NORTH 
DAKOTA, IN THE GREAT LAKES AND IN THE OHIO AND TENNESSEE VALLEYS. THERE ARE 
ELEVATED ODDS OF BELOW MEDIAN PRECIPITATION FROM SOUTHERN CALIFORNIA TO TEXAS 
AND ACROSS THE EAST GULF COAST REGION INCLUDING ALL OF FLORIDA, AND THE 
SOUTHERN ATLANTIC COAST, AS WELL AS FOR A NARROW BAND OVER THE SOUTHERN COAST 
OF ALASKA, FROM KODIAK ISLAND TO NEAR YAKUTAT.  ELSEWHERE, EQUAL CHANCES (EC) 
OF BELOW-, NEAR-, AND ABOVE-MEDIAN PRECIPITATION ARE PREDICTED.


FORECASTER: HUUG VAN DEN DOOL


NOTES: AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL 
PROBABILITIES) ARE NOW LABELED AS EC (EQUAL CHANCES).


THE NEXT MONTHLY OUTLOOK...FOR MAR ... WILL BE ISSUED ON THU FEB 17 2011


THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1971-2000 BASE PERIOD.

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