PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
830AM EDT THURSDAY JUL 15 2010

30-DAY OUTLOOK DISCUSSION FOR AUGUST 2010

SEA SURFACE TEMPERATURES (SST'S) NEAR THE EQUATOR IN THE EASTERN AND CENTRAL 
PACIFIC OCEAN FURTHER DECREASED IN JULY. SST ANOMALIES ARE NOW NEGATIVE ALONG 
THE EQUATOR FROM THE SOUTH AMERICAN COAST TO WEST OF THE DATE LINE AND BELOW 
NEGATIVE 1 DEGREE C EAST OF 160W LONGITUDE. THE CPC CONSOLIDATION SST FORECAST 
BASED ON THE CFS AND THREE STATISTICAL MODELS SUGGESTS THAT THE AVERAGE SST 
ANOMALY IN THE NINO 3.4 REGION (BETWEEN 5N AND 5S, 170W AND 120W) WILL REMAIN 
BELOW NORMAL THROUGH NEXT WINTER AND REACH LA NINA STATUS IN LATE SUMMER. FOR 
AUGUST WE NEED TO CONSIDER A BORDERLINE LA NINA CASE. IN GENERAL THE IMPACT OF 
ENSO ON THE US IS LIMITED IN NORTHERN HEMISPHERE SUMMER.
 
THE HALF MONTH LEAD AUGUST OUTLOOK IS BASED ON THE FOLLOWING TOOLS: CFS, CCA, 
SMLR, OCN, CAS AND SOME INFORMALLY USED TOOLS SUCH AS COASTAL SST, THE 
CONSTRUCTED ANALOGUE ON GLOBAL SST (CA-SST), ENSO COMPOSITES AND THE 
CONSIDERATION OF AN ACTIVE HURRICANE SEASON. CONSISTENCY WITH THE ASO SEASONAL 
FORECAST ALSO PLAYS A ROLE. 

THE TEMPERATURE OUTLOOK IS BASED ON UNUSUALLY CONSISTENT TOOLS FOR SUCH A SHORT 
PERIOD OF ONE MONTH IN SUMMER. SEVERAL TOOLS SHOW ENHANCED CHANCES FOR BELOW 
NORMAL TEMPERATURES OR EQUAL CHANCES FOR EACH CATEGORY IN TEXAS AND PARTS OF 
ADJACENT STATES, WITH A HALF DOUGHNUT OF ENHANCED CHANCES FOR ABOVE NORMAL 
TEMPERATURES EXTENDING FROM THE SOUTHWEST VIA THE NORTH-CENTRAL STATES TO THE 
EAST AND SOUTHEAST. THIS PATTERN IS SUPPORTED IN FULL BY CAS, CA-SST AND CCA 
AND PARTLY BY SMLR AND OCN. WE HELD OFF FROM FAVORING BELOW NORMAL TEMPERATURES 
IN THE OFFICIAL FORECAST IN THE CENTRAL SOUTHERN STATES BECAUSE SKILL IS LOW IN 
AUGUST AND THE ASO PREDICTION FAVORS ABOVE NORMAL TEMPERATURES. THE RESULT IS A 
BIG HOLE IN A PATTERN THAT IS OTHERWISE WARM ALMOST FROM COAST TO COAST. WE 
EXCLUDE THE IMMEDIATE WEST COAST FROM THE ABOVE NORMAL AREA BECAUSE SSTS ARE  
COLD THERE AND HAVE BEEN TRENDING DOWN RECENTLY. OF ALL TOOLS IT IS MAINLY CFS 
THAT SUPPORTS ENHANCED CHANCES FOR BELOW NORMAL TEMPERATURES ALONG THE WEST 
COAST. OVERALL WE THUS HAVE VERY HIGH COVERAGE AND EQUAL CHANCE ONLY ALONG THE 
WEST COAST AND THE SOUTH-CENTRAL REGION.

IN CONTRAST THE AUGUST OUTLOOK FOR PRECIPITATION SHOWS VERY LITTLE SIGNAL. OCN, 
SMLR AND CCA HAVE SCATTERED INDICATIONS FOR BELOW MEDIAN PRECIPITATIONND WE 
COMBINED THOSE INDICATIONS AND EXTENDED THEM SOUTHWARD TO EXPRESS A WEAK 
MONSOON SITUATION, ESPECIALLY IN ARIZONA. THE CAS, CFS AND CA-SST FAVOR ABOVE 
MEDIAN PRECIPITATION IN EAST TEXAS AND OKLAHOMA, WHICH WE EXTENDED EASTWARD 
ALONG THE GULF COAST IN VIEW OF THE ACTIVE TROPICAL SYSTEM SEASON. WE EXCLUDED 
FLORIDA, HOWEVER, BECAUSE SEVERAL TOOLS ARE ACTUALLY QUITE DRY FOR THAT STATE 
FOR AUGUST. UNCERTAINTY IN THE PRECIPITATION OUTLOOK LEADS TO A FORECAST OF 
EQUAL CHANCES (EC) OVER OTHER REGIONS.




FORECASTER: HUUG VAN DEN DOOL


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


AN UPDATED MONTHLY OUTLOOK... FOR AUG WILL BE ISSUED ON SAT JULY 31 2010


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

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