083
FXUS07 KWBC 011642
PMD30D
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EDT THU JUL 31 2008
30-DAY OUTLOOK DISCUSSION FOR AUGUST 2008
BELOW WE REPEAT THE PMD WRITTEN JULY 17 AT LONG LEAD.
IN VIEW OF THE SHORT RANGE NWP RUNS WE NOW HAVE AT OUR DISPOSAL WE HAVE MADE
THE FOLLOWING ADJUSTMENT IN THE AUGUST 2008 MONTHLY TEMPERATURE AND
PRECIPITATION PREDICTION. IN AREAS WHERE NWP FOR THE FIRST 5 DAYS DID NOT
STRONGLY CONTRADICT THE LONG LEAD PREDICTION NO ADJUSTMENTS WERE MADE.
TEMPERATURE. THE PREDICTED COLD CENTERED AT THE BORDER OF IA IL AND MISSOURI
HAS BEEN REMOVED BECAUSE THE NEXT 5 DAYS APPEAR TO BE EXTREMELY WARM. THIS AREA
IS NOW EC. BELOW NORMAL TEMPERATURES HAVE BEEN ADDED TO NM AND PORTIONS OF
SURROUNDING STATES - THIS IS IN LINE WITH PERSISTENCE OF A GOOD MONSOON AS WELL
AS MOST TOOLS. ALONG THE NORTHERN COAST OF AK WE ADDED SOME WARMTH BECAUSE THE
POSITIVE SST ANOMALIES HAVE BEEN BLOSSOMING.
PRECIPITATION. WE ADDED THREE AREAS OF ABOVE MEDIAN PRECIPITATION. TWO ARE
SUGGESTED BY NWP FOR THE NEXT 5 DAYS CENTERED IN NORTHERN MAINE AND
SOUTHWESTERN WISCONSIN. THE LATTER AREA WOULD ALSO BE PERSISTENCE OF PREVAILING
CONDITIONS AND IS ALSO IN LINE WITH MOST TOOLS. WE ALSO ADDED ABOVE MEDIAN
PRECIPITATION FOR NM PLUS PORTIONS OF SURROUNDING STATES - I.E. A CONTINUATION
OF A GOOD MONSOON.
OLD PMD JULY 17
SEA SURFACE TEMPERATURE (SST) ANOMALIES OVER THE CENTRAL EQUATORIAL PACIFIC
HAVE RISEN TO ABOUT ZERO AND CPC HAS CALLED FOR OFFICAL NEUTRAL CONDITIONS THUS
TERMINATING THE EL NINA STATUS. THE ATMOSPHERIC CIRCULATION THROUGHOUT THE
TROPICAL PACIFIC OCEAN REFLECTS WEAKENED LA NINA CONDITIONS, WITH WEAKER THOUGH
STILL ENHANCED LOW LEVEL EASTERLIES ALONG THE EQUATOR, SUPPRESSED CONVECTION IN
THE CENTRAL EQUATORIAL PACIFIC, AND ENHANCED CONVECTION OVER THE WESTERN
EQUATORIAL PACIFIC. THE CONSOLIDATION OF NUMERICAL AND STATISTICAL NINO 3.4
FORECASTS INDICATES ENSO NEUTRAL CONDITIONS THROUGH THE NEXT COUPLE MONTHS AND
DEFINITELY FOR AUGUST. ANY RESIDUAL ATMOSPHERIC EFFECTS OF THE RECENT LA NINA
ARE EXPECTED TO HAVE SMALL IMPACTS ON U.S. TEMPERATURES AND PRECIPITATION IN
AUGUST.
WE USED THE JAS SEASONAL FORECAST RELEASED LAST MONTH AS FIRST GUESS FOR
AUGUST. THE FOLLOWING TOOLS WERE CONSULTED - CCA CAS SMLR CFS OCN PLUS SOME
LOCAL CONSIDERATIONS ABOUT SST ALONG COASTLINES AND SOIL MOISTURE CONDITIONS.
BELOW NORMAL SST ANOMALIES ALONG THE PACIFIC COAST OF NORTH AMERICA - BUT NO
LONGER CALIFORNIA - ARE EXPECTED TO ALLOW BELOW NORMAL AIR TEMPERATURES FOR THE
COASTAL AREAS FROM THE SOUTHERN COAST OF ALASKA TO WESTERN WASHINGTON AND
OREGON. THE ENHANCED PROBABILITY OF ABOVE NORMAL TEMPERATURES IN THE
SOUTHWESTERN U.S. ARE DUE MOSTLY TO STRONG SUMMER TEMPERATURE TRENDS IN THESE
REGIONS AS INDICATED IN THE CAS SMLR AND OCN TOOLS. HOWEVER, THIS AREA OF ABOVE
NORMAL PROBABILITIES HAS BEEN REDUCED IN SIZE SUCH AS EXCLUDING NEW MEXICO
WHERE THE MONSOON HAS BEEN GOOD SO FAR AND APPEARS TO REMAIN GOOD IN THE SHORT
RUN - THUS CREATING A MOIST LOWER BOUNDARY. BELOW NORMAL TEMPERATURES ARE
INDICATED IN AN AREA CENTERED AT MISSOURI BY THE CAS AND THE CFS. WE KEPT THIS
AREA SOMEWHAT SMALL BECAUSE OCN CONTRADICTS COLD. ABOVE NORMAL TEMPERATURES ARE
MOST LIKELY FROM THE GULF COAST NORTHEASTWARD INTO THE CAROLINAS DUE TO OCN AND
SMLR WITH CCA CONTRADICTIONS KEEPING THE AREA SMALLER AND THE PROBABILITIES
MORE MODEST. THIS AREA OF ABOVE NORMAL TEMPERATURES ACROSS THE SOUTHEAST
COINCIDES ALSO WITH DEFICIENT SOIL MOISTURE. PROBABILITIES IN THE FLORIDA
PENNINSULA HAVE BEEN KEPT SMALL BECAUSE THE LOCAL SSTS HAVE TENDED COLD LATELY.
THE PRECIPITATION FORECAST FOR A PERIOD AS SHORT AS A MONTH - AT 0.5 MONTH LEAD
- IS NEARLY ALWAYS DIFFICULT AND FOR AUGUST 2008 WE HAVE PRACTICALLY NO SIGNALS
AT ALL. OF ALL THE ANOMALIES INDICATED IN JAS - OUR FIRST GUESS - WE ONLY HAVE
FAINT SUPPORT OF OCN FOR BELOW MEDIAN PRECIPITATION IN A SMALL AREA CENTERED AT
THE MEETING POINT OF OREGON IDAHO NEVADA AND CALIFORNIA.
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 SEPTEMBER 2008...WILL BE ISSUED ON THU AUG 21
2008
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1971-2000 BASE PERIOD.
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