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6-10 Day outlooks are issued daily between 3pm & 4pm Eastern Time. All forecasts issued on weekends are completely automated while all weekday outlooks are modified by the forecaster.
Please refer to the U.S. Prognostic Discussion for an explanation of terms and symbols used on these maps.
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Prognostic Discussions
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Valid: May 11 - 15, 2009 (6-10 Day Outlook)
Valid: May 13 - 19, 2009 (8-14 Day Outlook)
Issued: May 05, 2009 |
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PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS, MD
300 PM EDT TUE MAY 05 2009
6-10 DAY OUTLOOK FOR MAY 11 - 15 2009
TODAYS NUMERICAL FORECAST GUIDANCE FOR THE 500-HPA HEIGHT PATTERN IS IN FAIR
AGREEMENT FOR THE LARGE-SCALE MEAN FLOW OVER THE PACIFIC-NORTH AMERICAN REGION.
THERE ARE A NUMBER OF VARIATIONS BETWEEN MODEL RUNS IN BOTH AMPLITUDE AND PHASE
THAT WARRANT ONLY NEAR-AVERAGE CONFIDENCE.
YESTERDAYS 12Z EUROPEAN ENSEMBLE MEAN SOLUTION AND TODAYS 00Z CANADIAN ENSEMBLE
MEAN SOLUTION ARE PREFERRED AND ARE WEIGHTED MOST HEAVILY IN THE OFFICIAL
500-HPA HEIGHT BLEND - IN PART DUE TO THEIR BETTER PERFORMANCE OVER THE LAST 60
DAYS. MOST OF THE ENSEMBLE MEANS AND DETERMINISTIC RUNS PREDICT A SIGNIFICANT
RIDGE ANCHORED NEAR THE EASTERN ALEUTIANS FOR THE 6-10 DAY PERIOD, THOUGH THE
GFS SUPERENSEMBLE MEAN AND THE 00Z GFS ENSEMBLE MEAN ARE FORECASTING A RIDGE OF
MODEST STRENGTH FOR THIS TIME OF YEAR. SOME OF THE DOWNSTREAM DIFFERENCES ARE
RELATED TO THE PREDICTED INTENSITY OF THIS ALEUTIAN RIDGE. IN GENERAL,
SOLUTIONS DEPICTING THE STRONGER RIDGING SUCH AS THE EUROPEAN ENSEMBLE MEAN,
THE 06Z DETERMINISTIC GFS, AND YESTERDAYS 12Z ECMWF ARE ASSOCIATED WITH A
TROUGH OVER THE PACIFIC NORTHWEST BEING POSITIONED CLOSER TO THE COAST. THE
SOLUTIONS INDICATING WEAKER ALEUTIAN RIDGING (ESPECIALLY IN THE HEIGHT ANOMALY
FIELDS) ARE GENERALLY ASSOCIATED WITH A MORE PROGRESSIVE TROUGH ACROSS THE
INTERIOR PACIFIC NORTHWEST AND NORTHERN ROCKIES. SIGNIFICANT DIFFERENCES EXIST
BETWEEN MODEL RUNS REGARDING THE PREDICTED DEPTH AND LOCATION OF THE PACIFIC
NORTHWEST TROUGH. ACROSS THE SOUTHERN CONUS, THERE IS REASONABLE AGREEMENT
AMONG MODELS ON WEAK RIDGING, AND EITHER ZONAL FLOW OR WEAK CYCLONIC CURVATURE
OVER THE NORTHERN TIER OF STATES.
THERE IS AN ENHANCED LIKELIHOOD FOR ABOVE-AVERAGE TEMPERATURES FOR MUCH OF
WESTERN ALASKA ASSOCIATED WITH SOUTHWEST FLOW AHEAD OF THE MEAN LONGWAVE TROUGH
OVER THE BERING SEA. THE NORTHERN LIMIT OF THE PREDICTED WARMTH IS ALSO
CONSISTENT WITH THE EXPECTED POSITION OF A QUASI-STATIONARY FRONT ACROSS THE
STATE EARLY IN THE PERIOD. ABOVE-AVERAGE TEMPERATURES ARE ALSO FAVORED ACROSS
THE SOUTHERN HALF OF THE CONUS UNDER THE EAST-WEST ELONGATED RIDGE. AN
INCREASED CHANCE FOR BELOW-AVERAGE TEMPERATURES IS SHOWN FOR FAR NORTHEASTERN
ALASKA, THE INTERIOR NORTHWEST (CONUS), AND ALSO OVER NORTHERN MAINE. THESE
ANTICIPATED AREAS OF BELOW AVERAGE TEMPERATURE ARE DUE TO NEARBY UPPER LEVEL
TROUGHS AND ASSOCIATED SURFACE FRONTS.
ABOVE MEDIAN PRECIPITATION IS FAVORED OVER WESTERN ALASKA AND FROM THE NORTHERN
ROCKIES EASTWARD ACROSS THE NORTHERN PLAINS THEN SOUTHEASTWARD ACROSS MUCH OF
THE EAST-CENTRAL U.S. THE AREAS OF ABOVE MEDIAN PRECIPITATION ARE GENERALLY
ASSOCIATED WITH UPPER LEVEL TROUGHS AND SOUTHWEST FLOW AHEAD OF THEM. IN
ADDITION, THE COMBINATION OF ISENTROPIC UPLIFT/OVERRUNNING ASSOCIATED WITH A
SURFACE WARM FRONT, AND NEARBY LOW PRESSURE CENTERS INCREASES THE CHANCES FOR
ABOVE MEDIAN PRECIPITATION ACROSS THE EAST-CENTRAL STATES. BELOW MEDIAN
PRECIPITATION IS FORECAST OVER MUCH OF THE SOUTHERN CONUS (ASSOCIATED WITH
UPPER LEVEL SUBSIDENCE), AND ALSO OVER SOUTHEAST ALASKA INCLUDING THE PANHANDLE
(DUE TO DRIER NORTHERLY FLOW).
TODAYS OFFICIAL 500-HPA BLEND CONSISTS OF 15 PERCENT OF TODAY'S OPERATIONAL 0Z
GFS CENTERED ON DAY 8...25 PERCENT OF TODAY'S 0Z GFS ENSEMBLE MEAN CENTERED ON
DAY 8...25 PERCENT OF TODAY'S CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8...AND 35
PERCENT OF YESTERDAY'S EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 7.
MODEL OF THE DAY: ECMWF ENSEMBLE MEAN
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: NEAR-AVERAGE, 3 ON A SCALE OF 1 TO
5, DUE TO FAIR AGREEMENT AMONG THE MODELS AND TOOLS.
THE 6-10 DAY TEMPERATURE PROG IS BASED ON THE NAEFS TEMPERATURE OUTLOOK, ANALOG
COUNT SPECIFICATIONS FROM THE VARIOUS MODEL HEIGHT FIELDS AND THE OFFICIAL
BLEND, THE CDC TEMPERATURE OUTLOOK AND THE KLEIN SPECIFICATION FROM THE VARIOUS
MODELS. THE CPC AUTOMATIC TEMPERATURE FORECAST WAS NOT AVAILABLE TODAY.
THE 6-10 DAY PRECIPITATION PROG IS BASED ON THE NAEFS PRECIPITATION OUTLOOK,
ANALOG COUNT SPECIFICATIONS FROM THE VARIOUS MODELS AND OFFICIAL BLEND, THE CDC
PRECIPITATION OUTLOOK AND THE NEURAL NETWORK SPECIFICATIONS FROM THE VARIOUS
MODELS. IT IS ALSO CONSISTENT WITH FRONTAL POSITIONS FORECAST BY THE
HYDROMETEOROLOGICAL PREDICTION CENTER (HPC) FOR THE FIRST FEW DAYS OF THE
FORECAST PERIOD. THE CPC AUTOMATIC PRECIPITATION FORECAST WAS NOT AVAILABLE
TODAY.
8-14 DAY OUTLOOK FOR MAY 13 - 19 2009
FOR WEEK 2, A CONSENSUS OF MODEL RUNS SUGGESTS A SOMEWHAT MORE AMPLIFIED RIDGE
CENTERED OVER THE MISSISSIPPI RIVER VALLEY COMPARED TO THE EARLIER 6-10 DAY
FORECAST PERIOD. THE 500-HPA MANUAL BLEND DEPICTS A WEAK TROUGH MOVING INLAND
ACROSS THE WEST COAST STATES, AND ANOTHER WEAK TROUGH MOVING AWAY FROM THE
ATLANTIC SEABOARD. THE MANUAL BLEND ALSO SHOWS A SIGNIFICANTLY WEAKENED RIDGE
(RELATIVE TO THE BLENDED HEIGHT PROG FOR DAYS 6-10) ACROSS WESTERN PORTIONS OF
ALASKA. THE GFS SUPERENSEMBLE MEAN, AND THE 00Z AND 06Z GFS ENSEMBLE MEANS,
SEEM TO BE TOO QUICK IN DISMANTLING THE ALEUTIAN RIDGE AND THEREFORE THESE
MODELS WERE GIVEN LESS WEIGHT IN THE MANUAL BLEND. THIS REASONING APPEARS TO BE
SUPPORTED BY THE BLENDED COMPOSITE HEIGHT ANALOG, WHICH RESULTS FROM SELECTING
AND AVERAGING THE TEN BEST HISTORICAL MATCHES TO TODAYS OFFICIAL HEIGHT PROG.
THE COMPOSITE HEIGHT ANALOG, WHICH HAS A CORRELATION COEFFICIENT OF 0.86 WITH
TODAYS MANUAL BLEND, SHOWS A STRONG ANOMALOUS RIDGE CENTERED OVER THE ALEUTIANS.
ANOTHER CONSIDERATION FOR THIS WEEK 2 PERIOD IS THE PREDICTED POSITION OF THE
EAST-CENTRAL CONUS RIDGE AXIS. AT THIS TIME, WITH THE RIDGE AXIS EXPECTED OVER
THE MISSISSIPPI VALLEY, IT IS THOUGHT THAT SURFACE TEMPERATURES WILL RISE
ACROSS MOST OF THE EAST, WITH BACKDOOR COLD FRONT ACTIVITY UNLIKELY TO OCCUR
ACROSS THE NORTHEAST. AS THIS RIDGE AXIS PROGRESSES EASTWARD THOUGH, THE
CHANCES FOR COOL AND CLOUDY MARINE LAYER INTRUSIONS ALONG THE NORTHEAST COASTAL
PLAIN SHOULD INCREASE.
THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF 10 PERCENT OF TODAY'S OPERATIONAL
0Z GFS CENTERED ON DAY 11...15 PERCENT OF TODAY'S 0Z GFS ENSEMBLE MEAN CENTERED
ON DAY 11...30 PERCENT OF TODAY'S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 11...15
PERCENT OF TODAY'S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 11...AND 30 PERCENT
OF TODAY'S CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11.
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: NEAR-AVERAGE, 3 ON A SCALE OF 1
TO 5 DUE TO REASONABLE MODEL AGREEMENT, OFFSET BY CONSIDERABLE UNCERTAINTY IN
THE PRIOR 6-10 DAY PERIOD.
THE 8-14 DAY TEMPERATURE PROG IS BASED ON: THE NAEFS TEMPERATURE OUTLOOK,
ANALOG COUNT SPECIFICATIONS FROM THE VARIOUS MODEL HEIGHT FIELDS AND OFFICIAL
BLEND, THE CDC TEMPERATURE OUTLOOK AND THE KLEIN SPECIFICATION FROM THE VARIOUS
MODEL HEIGHT FIELDS. THE CPC AUTOMATIC TEMPERATURE FORECAST WAS NOT AVAILABLE
TODAY.
THE 8-14 DAY PRECIPITATION PROG IS BASED ON: THE NAEFS PRECIPITATION OUTLOOK,
ANALOG COUNT SPECIFICATIONS FROM THE VARIOUS MODELS, THE CDC PRECIPITATION
OUTLOOK AND THE NEURAL NETWORK SPECIFICATIONS FROM THE VARIOUS MODEL HEIGHT
FIELDS. THE CPC AUTOMATIC PRECIPITATION FORECAST WAS NOT AVAILABLE TODAY.
FORECASTER: ANTHONY ARTUSA
NOTES:
OPERATIONAL CHANGE: AS OF JULY 5 2005 SHADED MAPS HAVE REPLACED THE
CONTOUR-ONLY MAPS ON THE CPC WEB SITE. THE CONTOURED MAPS ARE
STILL AVAILABLE AT THEIR CURRENT FILE NAMES - SO DIRECT-LINKED USERS
ARE NOT AFFECTED. AWIPS GRAPHICS ARE ALSO NOT AFFECTED BY THIS
CHANGE.
AUTOMATED FORECASTS ARE ISSUED ON SATURDAY AND SUNDAY. OTHERWISE -
FORECASTS INCORPORATE FORECASTER INPUT.
THE NOTATION FOR THE CATEGORICAL FORECAST INDICATED ON THE MAPS IS
THE SAME AS THAT IN THE TABLES: A-ABOVE N-NEAR NORMAL B-BELOW
IN THE SOUTHWEST AND OTHER CLIMATOLOGICALLY DRY REGIONS - THERE WILL
BE A GREATER THAN 33.3% CHANCE OF NO PRECIPITATION AND OCCASIONALLY
EVEN A NORMAL (I.E. MEDIAN) VALUE OF ZERO - ESPECIALLY DURING THE DRY
SEASONS. IN SUCH CASES A FORECAST OF NEAR NORMAL IS EFFECTIVELY A
FORECAST OF LITTLE OR NO PRECIPITATION.
THE NARRATIVE DESCRIPTION OF THE FORECAST PATTERNS FOR TEMPERATURE
AND PRECIPITATION FOR BOTH THE 6-10 OR 8-14 DAY PERIODS HAS BEEN
DISCONTINUED. THE STATE TABLES FOR BOTH THE 6-10 AND 8-14 DAY
PERIODS ARE NOW CONTAINED IN THIS MESSAGE...AVAILABLE AS PMDMRD ON
AWIPS.
THE CLIMATE PREDICTION CENTER USES 1971-2000 BASE PERIOD MEANS FOR
TEMPERATURE...PRECIPITATION...AND 500-HPA HEIGHTS AS REFERENCE IN
THE CLIMATE OUTLOOKS.
THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON MAY
21.
NEW NOTE EFFECTIVE MAR 16 2004:
THE GLOSSARY FORMERLY FOUND AT THIS LOCATION WILL NO LONGER BE TRANSMITTED AS
PART OF THIS MESSAGE. IF YOU WISH TO SEE THE DEFINITIONS OF TERMS USED IN THESE
MESSAGES... PLEASE GO TO THE CPC WEB PAGE AT (USE LOWER CASE)
HTTP://WWW.CPC.NCEP.NOAA.GOV AND FOLLOW THE APPROPRIATE LINKS.
ANALOGS TO THE 5 DAY MEAN OBSERVED PATTERN CENTERED 3 DAYS AGO (D-3)
FOR THE REGION FROM 20N TO 70N LATITUDE AND 175E TO 60W LONGITUDE
INCLUDE THE 5 DAY PERIODS CENTERED ON THE FOLLOWING DATES:
19930424 - 19690518 - 19900416 - 19960513 - 20050504
ANALOGS TO THE 7 DAY MEAN OBSERVED PATTERN CENTERED 4 DAYS AGO (D-4)
FOR THE REGION FROM 20N TO 70N LATITUDE AND 175E TO 60W LONGITUDE
INCLUDE THE 7 DAY PERIODS CENTERED ON THE FOLLOWING DATES:
19900416 - 19960513 - 19930423 - 19690518 - 19970503
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 11 - 15 2009
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N N OREGON N N NRN CALIF N N
SRN CALIF A B IDAHO N N NEVADA N N
W MONTANA B A E MONTANA B A WYOMING N A
UTAH A B ARIZONA A B COLORADO A N
NEW MEXICO A B N DAKOTA N A S DAKOTA N A
NEBRASKA N N KANSAS A N OKLAHOMA A N
N TEXAS A B S TEXAS A B W TEXAS A B
MINNESOTA N A IOWA N A MISSOURI A A
ARKANSAS A A LOUISIANA A B WISCONSIN N A
ILLINOIS A A MISSISSIPPI A N MICHIGAN N N
INDIANA A A OHIO A N KENTUCKY A A
TENNESSEE A A ALABAMA A N NEW YORK N N
VERMONT N N NEW HAMP N N MAINE N N
MASS N N CONN N N RHODE IS N N
PENN N N NEW JERSEY N N W VIRGINIA A N
MARYLAND N N DELAWARE N N VIRGINIA A N
N CAROLINA A N S CAROLINA A B GEORGIA A B
FL PNHDL A B FL PENIN A B AK N SLOPE N N
AK ALEUTIAN A A AK WESTERN A A AK INT BSN N N
AK S INT A B AK SO COAST A B AK PNHDL N B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 13 - 19 2009
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N N OREGON N N NRN CALIF N N
SRN CALIF N B IDAHO N N NEVADA N B
W MONTANA N N E MONTANA N N WYOMING A N
UTAH A B ARIZONA A B COLORADO A B
NEW MEXICO A B N DAKOTA N A S DAKOTA A A
NEBRASKA A N KANSAS A B OKLAHOMA A B
N TEXAS A B S TEXAS A N W TEXAS A B
MINNESOTA A A IOWA A A MISSOURI A B
ARKANSAS A B LOUISIANA A B WISCONSIN A A
ILLINOIS A N MISSISSIPPI A B MICHIGAN A A
INDIANA A N OHIO A N KENTUCKY A N
TENNESSEE A B ALABAMA A B NEW YORK N N
VERMONT N N NEW HAMP N N MAINE N N
MASS N B CONN N B RHODE IS N B
PENN A N NEW JERSEY N B W VIRGINIA A N
MARYLAND A B DELAWARE A B VIRGINIA A B
N CAROLINA A B S CAROLINA A B GEORGIA A B
FL PNHDL A B FL PENIN N N AK N SLOPE B A
AK ALEUTIAN A A AK WESTERN N A AK INT BSN N N
AK S INT N B AK SO COAST N B AK PNHDL N B
LEGEND
TEMPS WITH RESPECT TO NORMAL PCPN WITH RESPECT TO MEDIAN
A - ABOVE N - NEAR NORMAL A - ABOVE N - NEAR MEDIAN
B - BELOW B - BELOW
THE FORECAST CLASSES REPRESENT AVERAGES FOR EACH STATE. NORMAL
VALUES - WHICH MAY VARY WIDELY ACROSS SOME STATES - ARE
AVAILABLE FROM YOUR LOCAL WEATHER SERVICE FORECAST OFFICE.
FOR ADDITIONAL INFORMATION SEE MESSAGE FXUS06 KWBC - ON AWIPS AS
PMDMRD.
$$
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