PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD 300 PM EST TUE FEB 28 2006 30-DAY OUTLOOK DISCUSSION FOR MARCH 2006 THE OCEANIC AND ATMOSPHERIC INDICATORS FOR THE TROPICAL PACIFIC OCEAN ARE CONSISTENT WITH LA NINA CONDITIONS. THE AREA OF BELOW NORMAL SSTS ALONG THE EQUATOR IN THE PACIFIC HAS EXTENDED WESTWARD TO AS FAR AS 15 DEGREES WEST OF THE DATE LINE... WITH MOST OF THIS AREA AT LEAST 0.5 DEG C BELOW NORMAL. SIGNIFICANTLY ABOVE NORMAL SSTS ARE CONFINED TO THE AREA WEST OF 155E. SOME NEAR NORMAL SSTS HAVE DEVELOPED NEAR THE SOUTH AMERICAN COAST... BUT AT DEPTH THERE IS A LARGE VOLUME OF COLDER THAN NORMAL WATER IN THE EASTERN EQUATORIAL PACIFIC... SO SSTS IN THE EASTERN PACIFIC ARE EXPECTED TO REMAIN NEAR OR BELOW NORMAL AT LEAST THROUGH MARCH. THE GRADIENT OF SSTS IN THE PACIFIC ALONG THE EQUATOR... BELOW NORMAL IN THE EAST AND CENTRAL PACIFIC AND ABOVE NORMAL OVER THE FAR WESTERN PACIFIC... IS EXPECTED TO HELP MAINTAIN STRONGER THAN AVERAGE LOW LEVEL EASTERLIES IN THE CENTRAL EQUATORIAL PACIFIC. THE DISTRIBUTION OF ANOMALOUS CONVECTION IN THE TROPICS HAS RESEMBLED A LA NINA FOR THE PAST FEW WEEKS... WITH HEAVY CONVECTIVE RAINFALL OVER INDONESIA AND VICINITY AND SUPPRESSED CONVECTION NEAR THE DATE LINE. THIS PATTERN IS EXPECTED TO DOMINATE THE EQUATORIAL PACIFIC AT LEAST INTO APRIL...HOWEVER THERE ARE BOUND TO BE OCCASIONAL SHORT-LIVED INTERRUPTIONS TO THIS MEAN PATTERN. A WEAK TO MODERATE MJO EXISTS AND IS CURRENTLY ASSOCIATED WITH A RECENT INCREASE IN CONVECTION OVER THE EASTERN EQUATORIAL INDIAN OCEAN AND INDONESIA...AS WELL AS LOW LEVEL WESTERLY ANOMALIES OVER THE CENTRAL INDIAN OCEAN. THE COMBINATION OF THIS WEAK TO MODERATE MJO AND THE UNDERLYING LA NINA CONDITIONS FAVOR WETTER THAN NORMAL CONDITIONS CONTINUING OVER INDONESIA AND THE FAR WESTERN PACIFIC DURING MARCH...IN ADDITION TO INCREASED CHANCES OF ABOVE AVERAGE RAINFALL FOR THE HAWAIIAN ISLANDS. THE DYNAMICAL MODEL FORECASTS OF MID-TROPOSPHERIC HEIGHT THROUGH THE MIDDLE OF MARCH SUGGEST THE PRESENCE OF A PROMINENT TROUGH OVER OR NEAR THE WEST COAST WHICH IS EXPECTED TO BRING RELATIVELY HEAVY AMOUNTS OF PRECIPITATION TO THAT REGION...WITH A TREND TOWARD LOWERING SNOW LEVELS ACROSS THE COASTAL AND INTERIOR MOUNTAIN RANGES OF THE FAR WEST. THE MODELS ALSO SUGGEST WEAK RIDGING OVER THE SOUTH-CENTRAL STATES AND A LINGERING TROUGH OFF THE U.S. ATLANTIC COAST. TOOLS USED FOR THE UPDATED MARCH 2006 TEMPERATURE FORECAST INCLUDE THE OCN... CFS...CAS...SMLR...CCA AND THE 3-WAY CONSOLIDATED FORECAST...AS WELL AS THE LATEST EXTENDED-RANGE MODEL GUIDANCE OUT THROUGH WEEK 2. MOST OF THE STATISTICAL TOOLS SUPPORT RELATIVE WARMTH OVER THE NORTHWESTERN HALF OF ALASKA...WITH CONSIDERABLE UNCERTAINTY OVER THE SOUTHEASTERN HALF. THE CFS MODEL PREDICTS BELOW AVERAGE TEMPERATURES OVER THE ENTIRE STATE...BUT HAS LITTLE SUPPORT FROM THE OTHER TOOLS. GIVEN CONFLICTING INDICATIONS FROM THE LATEST GFS MODEL RUNS AS WELL AS THE RECENT STRENGTHENING OF THE MJO WAVE OVER THE EASTERN INDIAN OCEAN...THE SURFACE TEMPERATURE FORECAST FOR ALASKA HAS BEEN CHANGED TO EQUAL CHANCES AND THE WEST COAST OF THE U.S. IS NOW FORECAST TO HAVE BELOW AVERAGE TEMPERATURES DURING MARCH. OVER THE PACIFIC NORTHWEST ...THE CAS - CFS - AND CCA SUPPORT BELOW NORMAL MEAN TEMPERATURES WHICH IS COMMONLY OBSERVED DURING LA NINA WINTERS. NEARLY ALL TOOLS FORECAST WARMTH OVER THE SOUTHWESTERN STATES...THOUGH THE WESTERN EDGE OF THIS WARMTH COULD BE ERODED BY NEAR- TO BELOW-NORMAL TEMPERATURES WITH THE ARRIVAL OF THE WEST COAST TROUGH AND ITS ASSOCIATED MOISTURE AND CLOUDINESS. THE WARMTH IS LIKELY TO BE CENTERED OVER THE SOUTH-CENTRAL CONUS WHICH HAS EXPERIENCED UNUSUALLY DRY CONDITIONS FOR THE PAST SEVERAL MONTHS. THE LATEST CAS STATISTICAL TOOL - WHICH IS UPDATED DAILY - HAS THE STRONGEST SIGNAL FOR WARMTH IN THAT AREA. KLEIN AND NEURAL NET TEMPERATURE SPECIFICATIONS FROM THE PATTERNS PREDICTED BY THE GFS MODEL RUNS ALSO SUGGEST WARMER THAN NORMAL CONDITIONS IN THIS AREA. FOR THE REMAINING LARGE PORTION OF THE LOWER 48 STATES...BOTH THE SET OF STATISTICAL TOOLS AVAILABLE TWO WEEKS AGO AND CURRENT GFS MODEL SPECIFICATIONS GIVE EITHER WEAK OR SLIGHTLY CONFLICTING INDICATIONS...SO EQUAL CHANCES (EC) IS PROBABLY THE BEST BET FOR THIS EXTENSIVE AREA IN THE ABSENCE OF ANY CLEAR-CUT AND SIGNIFICANT SIGNALS. THE PRECIPITATION FORECAST FOR THE LOWER 48 STATES AND ALASKA IS ALSO BASED LARGELY ON PAST HISTORICAL CLIMATE RESPONSES FROM LA NINA FORCING OVER THE TROPICAL PACIFIC. THE SMLR...CFS...AND OCN TOOLS (AND TO A LESSER EXTENT THE CCA) FAVOR RELATIVE WETNESS OVER THE PACIFIC NORTHWEST...AND ALSO FROM THE OHIO AND TENNESSEE VALLEYS NORTHEASTWARD THROUGH NEW YORK AND NEW ENGLAND. HOWEVER ...THIS LATTER AREA IS UNCERTAIN GIVEN RECENT DYNAMICAL MODEL INPUT AND THUS THE ABOVE MEDIAN SHOWN IN THE EARLIER FORECAST WAS REPLACED WITH EC. RELATIVE DRYNESS IS FORECAST OVER THE SOUTHERN AND CENTRAL PLAINS...AND PARTS OF THE SOUTHEAST BY THE SMLR AND CFS WITH SOME SUPPORT FROM NEURAL NET SPECIFICATIONS FROM RECENT GFS MODEL FORECASTS FOR THE NEXT TWO WEEKS. THERE ARE CONFLICTING SIGNALS REGARDING ALASKA PRECIPITATION FOR THE MONTH OF MARCH...AND ALTHOUGH NEURAL NET SPECIFICATIONS FROM THE GFS MODELS SUGGEST WET IN THE WEST AND DRY FOR THE SOUTH COAST AND PANHANDLE FOR THE NEXT TWO WEEKS...THERE IS NO ASSURANCE THAT THIS PATTERN WILL LAST FOR THE WHOLE MONTH. THEREFORE THE STATE WAS LEFT AS EC. FORECASTER: A. ARTUSA NOTES - AREAS OF UNCERTAINTY THAT FORMERLY WERE LABELED CL (CLIMATOLOGICAL PROBABILITIES) ARE NOW LABELED EC (EQUAL CHANCES). THE NEXT MONTHLY OUTLOOK... FOR APRIL 2006... WILL BE ISSUED ON THU MAR 16 2006 THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1971-2000 BASE PERIOD. $$