PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS, MD
300 PM EDT THU SEPTEMBER 09 2010
6-10 DAY OUTLOOK FOR SEP 15 - 19 2010
RECENT ENSEMBLE MEAN SOLUTIONS ARE IN FAIRLY GOOD AGREEMENT ON THE EXPECTED
MEAN 500-HPA CIRCULATION PATTERN OVER NORTH AMERICA FOR THE 6-10 DAY PERIOD.
TROUGHS ARE FORECAST NORTH OF HUDSON BAY EXTENDING SOUTHEASTWARD TO THE
NORTHEAST ATLANTIC AND OVER THE EASTERN GULF OF ALASKA/WESTERN CANADIAN COAST.
A SUBTROPICAL RIDGE IS EXPECTED OVER THE SOUTHWEST CONUS EXTENDING
NORTHWESTWARD TO THE ROCKIES, GREAT BASIN, WESTERN CANADA, AND ALASKA. THE
TROUGH ANTICIPATED OVER THE GULF OF ALASKA IS FORECAST TO UNDERCUT THE RIDGE
EXPECTED OVER ALASKA. THE ECMWF-BASED ENSEMBLES INDICATE HIGHER HEIGHTS OVER
THE SOUTHEAST. THE LATEST OPERATIONAL RUNS OF THE ECMWF AND GFS ARE IN
BASICALLY GOOD AGREEMENT WITH THEIR RESPECTIVE ENSEMBLE MEANS ALTHOUGH AS USUAL
THE OPERATIONAL RUNS ARE GENERALLY MORE AMPLIFIED WITH THE MAIN CIRCULATION
FEATURES. YESTERDAYS 12Z OPERATIONAL ECMWF DEPICTS LOWER HEIGHTS OVER THE UPPER
MISSISSIPPI VALLEY AND GREAT LAKES COMPARED TO THE OTHER MODEL SOLUTIONS.
THE ENSEMBLE SPAGHETTI DIAGRAMS GENERALLY INDICATE MODERATE SPREAD OVER MUCH OF
THE FORECAST DOMAIN. THE PNA INDEX WHICH RECENTLY HAS BEEN POSITIVE IS FORECAST
TO REMAIN POSITIVE THROUGH DAY 14. THE AO INDEX WHICH RECENTLY HAS BEEN
NEGATIVE IS FORECAST TO REMAIN NEGATIVE THROUGH DAY 14.
TODAYS BLEND CHART INDICATES NEAR TO BELOW NORMAL HEIGHTS OVER THE EASTERN AND
NORTHWESTERN CONUS, AND NEAR TO ABOVE NORMAL HEIGHTS OVER THE SOUTHWEST, THE
CENTRAL AND SOUTHERN ROCKIES, THE PLAINS, LOWER MISSISSIPPI VALLEY AND ALASKA.
THE AREA OF BELOW NORMAL HEIGHTS EXPECTED OVER THE NORTHEAST FAVORS BELOW
NORMAL TEMPERATURES FOR PARTS OF THE NORTHEAST, MIDDLE ATLANTIC, GREAT LAKES
AND UPPER MISSISSIPPI VALLEY. COOLER THAN NORMAL SEA SURFACE TEMPERATURES
FAVORS BELOW NORMAL TEMPERATURES FOR COASTAL SECTIONS OF CALIFORNIA. THE
EXPECTATION OF NEAR TO ABOVE NORMAL HEIGHTS FAVORS ABOVE NORMAL TEMPERATURES
FOR ALASKA, THE INTERIOR WESTERN CONUS, AND ALONG MUCH OF THE GULF COAST.
THE TROUGH EXPECTED TO APPROACH THE PACIFIC NORTHWEST LEADS TO A FORECAST OF
ENHANCED CHANCES FOR ABOVE MEDIAN PRECIPITATION FOR COASTAL SECTIONS OF THAT
REGION. SURFACE LOW PRESSURE EXPECTED OVER THE CENTRAL PLAINS AND MIDDLE
MISSISSIPPI VALLEY FAVORS ABOVE MEDIAN PRECIPITATION FOR PARTS OF THOSE
REGIONS. MUCH OF THE REST OF THE CONUS AND ALASKA IS FAVORED TO HAVE BELOW
MEDIAN PRECIPITATION. THE PRECIPITATION FORECAST ALONG THE GULF COAST AND
FLORIDA IS HIGHLY UNCERTAIN BECAUSE OF THE POSSIBILITY OF TROPICAL ACTIVITY
DURING THE PERIOD.
TODAY'S OFFICIAL 500-HPA BLEND CONSISTS OF 15 PERCENT OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8...15 PERCENT OF TODAY'S 6Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8...5 PERCENT OF TODAY'S OPERATIONAL 0Z ECMWF CENTERED ON DAY
8...20 PERCENT OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8...5
PERCENT OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8...5 PERCENT OF
YESTERDAY'S OPERATIONAL 12Z ECMWF CENTERED ON DAY 7...30 PERCENT OF YESTERDAY'S
12Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 7...AND 5 PERCENT OF YESTERDAY'S 12Z
CANADIAN ENSEMBLE MEAN CENTERED ON DAY 7.
MODEL OF THE DAY: YESTERDAY'S 12Z ECMWF ENSEMBLE
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 ON A SCALE OF 1
TO 5, DUE TO GOOD MODEL AGREEMENT DEPICTING THE OVERALL PATTERN AND FAIRLY GOOD
AGREEMENT OF THE FORECAST TOOLS.
8-14 DAY OUTLOOK FOR SEP 17 - 23 2010
FOR WEEK 2, THE ENSEMBLE MEANS INDICATE THE OVERALL CIRCULATION PATTERN WILL BE
SLIGHTLY DEAMPLIFIED AND SLOWLY PROGRESSIVE COMPARED TO THE FORECAST FOR THE
6-10 DAY PERIOD. A ZONAL FLOW PATTERN IS EXPECTED ACROSS THE NORTHERN CONUS.
RECENT OPERATIONAL GFS RUNS ARE IN FAIRLY GOOD AGREEMENT WITH THE ENSEMBLE
MEANS ALTHOUGH THE 0Z OPERATIONAL GFS IS NOTICEABLY MORE AMPLIFIED WITH THE
MAIN CIRCULATION FEATURES. THE ENSEMBLE SPAGHETTI CHARTS INDICATE MODERATE
SPREAD OVER MOST OF THE FORECAST DOMAIN, AND FOR THE CANADIAN AND ECMWF
ENSEMBLES, MODERATE TO LARGE SPREAD OVER THE CENTRAL ATLANTIC AND GULF OF
MEXICO WHICH IS A REFLECTION OF THE UNCERTAINTY ASSOCIATED WITH THE FUTURE
EVOLUTION OF TROPICAL SYSTEMS.
TODAYS WEEK 2 BLEND CHART INDICATES NEAR TO BELOW NORMAL HEIGHTS OVER THE
ALASKAN PANHANDLE, THE NORTHWEST CONUS, AND ALONG THE EAST AND GULF COASTS, AND
NEAR TO ABOVE NORMAL HEIGHTS OVER THE REMAINDER OF THE CONUS AND ALASKA.
AS AN UPPER-LEVEL RIDGE MOVES SLOWLY EASTWARD, A WARMER PATTERN IS EXPECTED
OVER THE UPPER MISSISSIPPI VALLEY AND PARTS OF THE SOUTHEAST DURING WEEK 2
COMPARED TO THE 6-10 DAY PERIOD. SHORTWAVE ENERGY RIDING OVER THE TOP OF THE
CENTRAL U.S. RIDGE FAVORS ABOVE MEDIAN PRECIPITATION OVER PARTS OF THE NORTHERN
PLAINS AND UPPER MISSISSIPPI VALLEY. OTHERWISE THE FORECAST ANOMALY PATTERNS
FOR WEEK 2 ARE NOT SUBSTANTIALLY DIFFERENT FROM THOSE FORECAST DURING THE 6-10
DAY PERIOD.
THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 5 PERCENT OF TODAY'S OPERATIONAL
0Z GFS CENTERED ON DAY 11...5 PERCENT OF TODAY'S 0Z GFS ENSEMBLE MEAN CENTERED
ON DAY 11...10 PERCENT OF TODAY'S GFS SUPERENSEMBLE MEAN CENTERED ON DAY
11...30 PERCENT OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11...10
PERCENT OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11...35 PERCENT OF
YESTERDAY'S 12Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 10...AND 5 PERCENT OF
YESTERDAY'S 12Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 10.
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 ON A SCALE OF
1 TO 5, DUE TO FAIR MODEL AGREEMENT OFFSET BY THE UNCERTAINTY OF A FORECAST IN
ZONAL FLOW AND UNCERTAINTIES ASSOCIATED WITH THE EVOLUTION OF SYSTEMS IN THE
TROPICS.
FORECASTER: RANDY SCHECHTER
NOTES:
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 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
SEPTEMBER 16
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:
19540826 - 19640901 - 19540913 - 19770923 - 19510829
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:
19540825 - 19640901 - 19540913 - 19970819 - 19850909
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 15 - 19 2010
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N N OREGON N N NRN CALIF N N
SRN CALIF N B IDAHO A B NEVADA A B
W MONTANA A N E MONTANA A B WYOMING A B
UTAH A B ARIZONA A B COLORADO A B
NEW MEXICO A B N DAKOTA N B S DAKOTA N B
NEBRASKA N N KANSAS N N OKLAHOMA A N
N TEXAS A B S TEXAS A N W TEXAS A B
MINNESOTA B N IOWA B A MISSOURI N A
ARKANSAS N N LOUISIANA A N WISCONSIN B N
ILLINOIS N A MISSISSIPPI N B MICHIGAN B A
INDIANA B A OHIO B A KENTUCKY N N
TENNESSEE N N ALABAMA N B NEW YORK B N
VERMONT B N NEW HAMP B N MAINE N A
MASS B N CONN B N RHODE IS B N
PENN B B NEW JERSEY B B W VIRGINIA B B
MARYLAND B B DELAWARE B B VIRGINIA B B
N CAROLINA N B S CAROLINA N B GEORGIA N B
FL PNHDL A N FL PENIN A N AK N SLOPE N B
AK ALEUTIAN A A AK WESTERN A B AK INT BSN A B
AK S INT A B AK SO COAST A B AK PNHDL A B
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 17 - 23 2010
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B N NRN CALIF N N
SRN CALIF N B IDAHO N N NEVADA A B
W MONTANA A N E MONTANA A N WYOMING A B
UTAH A B ARIZONA A B COLORADO A B
NEW MEXICO A B N DAKOTA A A S DAKOTA A N
NEBRASKA A B KANSAS A B OKLAHOMA A B
N TEXAS A N S TEXAS N N W TEXAS A B
MINNESOTA A A IOWA A N MISSOURI A N
ARKANSAS A N LOUISIANA N N WISCONSIN A A
ILLINOIS N N MISSISSIPPI N B MICHIGAN N N
INDIANA N B OHIO N B KENTUCKY N B
TENNESSEE N B ALABAMA N B NEW YORK B B
VERMONT N N NEW HAMP N N MAINE N N
MASS B N CONN B N RHODE IS B N
PENN B B NEW JERSEY B B W VIRGINIA B B
MARYLAND B B DELAWARE B N VIRGINIA B B
N CAROLINA B B S CAROLINA B B GEORGIA B B
FL PNHDL N N FL PENIN N N AK N SLOPE A B
AK ALEUTIAN N A AK WESTERN N N AK INT BSN A B
AK S INT A B AK SO COAST A B AK PNHDL N N
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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