057
FXUS07 KWBC 302041
PMD30D
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EDT MON JUN 30 2008
30-DAY OUTLOOK DISCUSSION FOR JULY 2008
SEA SURFACE TEMPERATURE (SST) ANOMALIES OVER THE CENTRAL EQUATORIAL PACIFIC
REMAIN BETWEEN 0.5 AND 1.0 DEGREES BELOW NORMAL. THE MAGNITUDE AND EASTWARD
EXTENT OF THE NEGATIVE ANOMALIES HAS BEEN DIMINISHING IN RECENT WEEKS AS ABOVE
NORMAL SST ANOMALIES IN THE EASTERN PACIFIC ARE INCREASING. BELOW NORMAL SST
ANOMALIES IN THE NORTH PACIFIC MAKE A TYPICAL LA NINA HORSESHOE PATTERN
EXTENDING FROM ALONG THE EQUATOR NEAR THE DATELINE NORTHEASTWARD TO THE
CALIFORNIA COAST, THEN FOLLOWING THE PACIFIC COAST OF NORTH AMERICA INTO THE
GULF OF ALASKA, THOUGH A POSITIVE SST ANOMALY HAS DEVELOPED OFF THE SOUTHERN
CALIFORNIA COAST IN THE LAST TWO WEEKS. SSTS IN THE NINO 3.4 REGION (BETWEEN 5
N AND 5 S, AND 170 W AND 120 W) HAVE NOW WARMED TO ABOUT 0.4 DEGREES CELSIUS
BELOW NORMAL AS OF THE END OF MAY. 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.
THE MOST RECENT CFS MODEL RUNS CONTINUE TO INDICATE RAPID WARMING OF THE
EQUATORIAL PACIFIC SSTS DURING JULY. THE MONTHLY MEAN SST ANOMALY IN THE NINO
3.4 REGION IS EXPECTED TO BE NEAR-NORMAL (LESS THAN HALF A DEGREE CELSIUS) FOR
JUNE AND JULY. ANY RESIDUAL ATMOSPHERIC EFFECTS OF THE RECENT LA NINA ARE
EXPECTED TO HAVE SMALL IMPACTS ON U.S. TEMPERATURES AND PRECIPITATION IN JULY.
FOR THE UPDATE TO THE JULY MONTHLY FORECAST MADE JUNE 30, THE MOST RECENT GFS
ENSEMBLES AND CFS MODEL FORECASTS HAVE BEEN EXAMINED. RECENT CFS MODEL
SIMULATIONS INDICATE AN UPPER LEVEL HEIGHT AND SURFACE TEMPERATURE PATTERN VERY
SIMILAR TO RUNS MADE FROM INITIAL CONDITIONS TWO WEEKS PRIOR. THE LATEST GFS
ENSEMBLES INDICATE PERSISTENT RIDGING OVER THE WESTERN CONUS FROM THE FOUR
CORNERS REGION INTO THE NORTHWEST WITH A WEAK TROUGH OVER THE EASTERN CONUS.
BELOW NORMAL SST ANOMALIES ALONG THE PACIFIC COAST OF NORTH AMERICA ARE
EXPECTED TO ALLOW BELOW NORMAL AIR TEMPERATURES FOR IMMEDIATE COASTAL AREAS
FROM THE SOUTHERN COAST OF ALASKA TO WESTERN WASHINGTON AND OREGON. RECENT
WARMING OF SST ANOMALIES ALONG THE CALIFORNIA COAST AND DRY CONDITIONS IN
CALIFORNIA HAVE LED TO AN EXPANSION OF THE ENHANCED PROBABILITY OF ABOVE NORMAL
TEMPERATURES TOWARDS THE COAST. THE ENHANCED PROBABILITY OF ABOVE NORMAL
TEMPERATURES IN THE SOUTHWESTERN U.S. AND THE GREAT BASIN ARE DUE MOSTLY TO
LARGE SUMMER TEMPERATURE TRENDS IN THESE REGIONS AS INDICATED IN THE CCA AND
OCN TOOLS. HOWEVER, THIS AREA OF ABOVE NORMAL PROBABILITIES HAS BEEN EXPANDED
INTO THE INTERMOUNTAIN WEST AND NORTHERN ROCKIES AS INDICATED BY THE RECENT GFS
ENSEMBLE FORECASTS. MUCH ABOVE NORMAL SOIL MOISTURE ANOMALIES AND INCREASED
EVAPORATIVE COOLING, ALONG WITH EXPECTED BELOW NORMAL MEAN UPPER LEVEL HEIGHTS
OVER PARTS OF THE EASTERN U.S. INDICATED BY THE CFS AND GFS FORECASTS, RESULTS
IN AN ENHANCED PROBABILITY FOR BELOW NORMAL TEMPERATURES OVER PORTIONS OF THE
U.S. MIDWEST INCLUDING THE CENTRAL MISSISSIPPI AND WESTERN OHIO VALLEYS. ABOVE
NORMAL TEMPERATURES ARE MOST LIKELY FROM THE GULF COAST NORTHEASTWARD INTO THE
SOUTHERN MID-ATLANTIC COAST INDICATED BY THE GFS FORECAST AND PARTLY SUPPORTED
BY THE CFS.
LOCAL SOIL MOISTURE CONDITIONS ARE ASSOCIATED WITH AN INCREASED PROBABILITY OF
ABOVE MEDIAN RAINFALL FOR THE CENTRAL MISSISSIPPI VALLEY AND OHIO VALLEY. THE
PACIFIC NORTHWEST IS EXPECTED TO DRY OUT AS FORECAST BY THE GFS ENSEMBLES AND
SUPPORTED BY THE CFS AND THE CAS, AND CONSISTENT WITH PRECIPITATION TRENDS.
RECENT GFS FORECASTS LEAD TO AN ENHANCED PROBABILITY OF ABOVE MEDIAN RAINFALL
FOR NEW MEXICO INTO COLORADO AS CONDITIONS ARE FAVORABLE FOR AN ACTIVE
SOUTHWEST MONSOON IN THIS REGION. RECENT GFS FORECASTS ALSO INDICATE AN
ENHANCED PROBABILITY OF ABOVE MEDIAN RAINFALL ALONG THE SOUTHEAST COAST OF
TEXAS.
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 AUGUST 2008...WILL BE ISSUED ON THU JUL 17 2008
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1971-2000 BASE PERIOD.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page