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FXUS06 KWBC 252033
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EST TUE NOVEMBER 25 2014

6-10 DAY OUTLOOK FOR DEC 01 - 05 2014

THERE IS GOOD AGREEMENT AMONG TODAY`S MODEL FORECASTS OF THE 6-10 DAY MEAN
500-HPA HEIGHTS OVER NORTH AMERICA. A RIDGE IS FORECAST TO BE NEAR THE
NORTHEASTERN CONUS WITH ZONAL FLOW FORECAST OVER THE WESTERN AND CENTRAL CONUS.
MODELS PREDICT A SHARP GRADIENT BETWEEN THE EXPECTED COLD AIR OVER WESTERN AND
CENTRAL CANADA AND RELATIVE MILD AIR OVER THE CENTRAL AND SOUTHERN CONUS.
TIMING DIFFICULTIES ARE EXPECTED TO COMPLICATE THE FORECAST FOR TEMPERATURES,
AS A SHALLOW, COLD AIR MASS IS EXPECTED TO SPREAD EASTWARD FROM THE NORTHERN
GREAT PLAINS EARLY IN THE 6-10 DAY PERIOD. A COLD START FOR THE EASTERN PORTION
OF THE COUNTRY IS EXPECTED TO BE FOLLOWED BY A RAPID WARM UP, AND AN INCREASE
IN CHANCES OF WET CONDITIONS AS SOUTHERLY RETURN FLOW BRINGS MOISTURE FROM THE
GULF OF MEXICO. SOUTHERN AND CENTRAL CALIFORNIA IS EXPECTED TO SEE WET
CONDITIONS AT THE START OF THE PERIOD, UNDER THE INFLUENCE OF A SHARP
UPPER-LEVEL TROUGH. THE GFS SOLUTIONS TEND TO BE QUICKER TO MOVE THIS TROUGH
EASTWARD THAN THE ECMWF, WHICH WILL MAKE CONDITIONS LATER IN THE 6-10 DAY
PERIOD AND INTO WEEK-TWO UNCERTAIN. MODELS AGREE ON MOSTLY BELOW NORMAL 500-HPA
HEIGHTS OVER EASTERN ALASKA THROUGH THE PERIOD.

ABOVE-NORMAL HEIGHTS OVER THE EASTERN HALF OF THE CONUS LEAD TO ENHANCED
CHANCES OF ABOVE-NORMAL TEMPERATURES, ESPECIALLY IN THE SOUTHEAST. CONFIDENCE
IN THE NORTH IS DIMINISHED DUE TO AN EXPECTED COLD START TO THE PERIOD. MOST
MODELS PREDICT RELATIVELY MILD AIR OVER MUCH OF THE WEST, IN SPITE OF THE
FORECAST OF A STRONG TROUGH THAT WILL INFLUENCE THE SOUTHWEST EARLY IN THE
PERIOD, FAVORING ABOVE-NORMAL TEMPERATURES. BELOW-NORMAL TEMPERATURES ARE
FAVORED FOR PARTS OF THE NORTHERN ROCKY MOUNTAINS EASTWARD TO THE UPPER
MISSISSIPPI VALLEY. A SHARP TEMPERATURE GRADIENT IS EXPECTED IN THE NORTHERN
CONUS, LEADING TO UNCERTAINTY IN THE CENTRAL GREAT PLAINS, WHERE ANY UNFORESEEN
TROUGH AMPLIFICATION MAY ALLOW COLD AIR TO PENETRATE DEEPER INTO THE REGION
THAN ANTICIPATED. BELOW-NORMAL TEMPERATURES ARE FAVORED FOR EASTERN AND CENTRAL
ALASKA UNDER BELOW NORMAL 500-HPA HEIGHTS, ALTHOUGH NEAR-NORMAL TEMPERATURES
ARE FAVORED NEAR THE COASTS WHERE ABOVE-NORMAL SEA SURFACE TEMPERATURES ARE
EXPECTED TO MODERATE TEMPERATURES.

ENHANCED WESTERLY FLOW OVER THE PACIFIC LEADS TO ELEVATED CHANCES FOR
ABOVE-MEDIAN PRECIPITATION AMOUNTS FOR MUCH OF THE WESTERN CONUS. EXPECTED
SOUTHWESTERLY FLOW AT 500-HPA SHOULD OPEN MUCH OF THE EAST TO MOISTURE FROM THE
GULF OF MEXICO, ENHANCING CHANCES FOR ABOVE-MEDIAN PRECIPITATION. A RELATIVELY
NARROW REGION OF NEAR- TO BELOW-MEDIAN PRECIPITATION IS EXPECTED TO THE LEE OF
THE ROCKIES WHERE LIMITED MOISTURE SUPPLY IN ZONAL FLOW MAY REDUCE
PRECIPITATION AMOUNTS. THE GFS FAVORS BELOW-MEDIAN PRECIPITATION AMOUNTS IN
MUCH OF ALASKA EXCEPT FOR IN THE ALEUTIANS.

TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 30% OF TODAY`S 6Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8, 40% OF TODAY`S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8,
AND 30% OF TODAY`S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8


MODEL OF THE DAY: 0Z ECMWF ENSEMBLE MEAN

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOUT AVERAGE, 3 OUT OF 5, DUE TO
GOOD MODEL AGREEMENT ON AN AMPLIFIED RIDGE IN THE EAST, BUT CONSIDERABLE
UNCERTAINTY ASSOCIATED WITH THE POSSIBLE INFLUENCE OF COLD AIR EXPECTED EARLY
IN THE PERIOD OVER THE EASTERN CONUS.

8-14 DAY OUTLOOK FOR DEC 03 - 09 2014

CONSIDERABLE TIMING DIFFICULTIES BETWEEN MODELS BECOME EVIDENT BY THE 8-14 DAY
PERIOD. THE TROUGH INITIALLY NEAR THE SOUTHERN CALIFORNIA COAST AT THE START OF
THE 8-14 DAY PERIOD IS CONSIDERABLY MORE PROGRESSIVE IN GEFS PREDICTIONS THAN
THE ECMWF ENSEMBLES SUGGEST. THIS ALLOWS THE GEFS TO BUILD 500-HPA HEIGHTS OVER
THE WEST COAST FASTER THAN DOES THE ECMWF. THE 8-14 MEAN GEFS SOLUTION SHOWS A
DISTINCTLY DEEPER TROUGH OVER THE CENTRAL AND EASTERN CONUS COMPARED TO THE
ECMWF. BOTH MODELS PREDICT 500-HPA HEIGHTS TO BE SLIGHTLY ABOVE NORMAL OVER
MOST OF THE CONUS AND CONTINUE TO FORECAST A RIDGE OFF THE COAST OF NEW
ENGLAND. THIS FAVORS ABOVE-NORMAL TEMPERATURES FOR MUCH OF THE COUNTRY, BUT THE
DEEPER TROUGH FORECAST BY THE GEFS LEADS TO REDUCED CONFIDENCE IN THE CENTRAL
PART OF THE COUNTRY.

PRECIPITATION EXPECTED OVER SOUTHERN CALIFORNIA AND THE SOUTHWEST MAY LINGER
INTO THE EARLY PART OF THE 8-14 DAY PERIOD, ESPECIALLY IF THE ECMWF SOLUTIONS
PROVE MORE ACCURATE, WHILE DRIER CONDITIONS ARE EXPECTED FOR MUCH OF THE WEST
LATER IN THE PERIOD. THIS LEADS TO SLIGHTLY ENHANCED CHANCES FOR ABOVE-MEDIAN
PRECIPITATION OVER THE SOUTHWEST, WHILE CHANCES FOR BELOW-MEDIAN PRECIPITATION
ARE SLIGHTLY ENHANCED IN NORTHERN CALIFORNIA UNDER BUILDING HEIGHTS. THE
CHANCES OF A BUILDING RIDGE OVER THE WEST INCREASES THE CHANCES OF ABOVE-MEDIAN
PRECIPITATION ALONG THE ALASKA PANHANDLE. ELSEWHERE THE PRECIPITATION OUTLOOK
FOR 8-14 DAYS REMAINS SIMILAR TO THE 6-10 DAY OUTLOOK.

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 30% OF TODAY`S 6Z GFS ENSEMBLE
MEAN CENTERED ON DAY 11, 40% OF TODAY`S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON
DAY 11, AND 30% OF TODAY`S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOUT AVERAGE, 3 OUT OF 5, DUE
TO FAIRLY GOOD AGREEMENT AMONG THE MODELS, OVER THE EASTERN CONUS, AND ALASKA,
BUT WITH DIFFERENCES BETWEEN THE ECMWF AND GEFS LEADING TO REDUCED CONFIDENCE
IN THE CENTRAL AND SOUTHWESTERN CONUS.

FORECASTER: DAVE UNGER

NOTES:


AUTOMATED FORECASTS ARE ISSUED ON SATURDAY AND SUNDAY. OCCASIONALLY MANUAL
INTERVENTION IS NECESSARY TO ADDRESS QUALITY CONTROL AND CONSISTENCY ISSUES.
IN THESE CASES, FORECASTS ARE MANUALLY DRAWN BUT A FULL DISCUSSION IS NOT
ISSUED.

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

THE TEMPERATURE MAP SHOWS REGIONS WITH > 33% CHANCE OF BEING WARMER
(ORANGE, "A"), COLDER (BLUE, "B"), OR CLOSE TO (UNSHADED, "N")
HISTORICAL AVERAGE VALUES FOR THE CALENDAR PERIOD OF THE FORECAST
(DASHES, "F").  LABELS ON THE SHADED LINES GIVE THE PROBABILITY
(> 33%) OF THE MORE LIKELY CATEGORY (B OR A).  PROBABILITY OF N IS
ALWAYS < 40%.

THE PRECIPITATION MAP SHOWS REGIONS WITH > 33% CHANCE OF BEING
WETTER (GREEN, "A"), DRIER (TAN, "B"), OR CLOSE TO (UNSHADED, "N")
HISTORICAL MEDIAN VALUES FOR THE CALENDAR PERIOD OF THE FORECAST
(DASHES, "INCHES").  LABELS ON THE SHADED LINES GIVE THE PROBABILITY
(> 33%) OF THE MORE LIKELY CATEGORY (B OR A).  PROBABILITY OF N IS
ALWAYS < 40%.

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 1981-2010 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
DECEMBER 18

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:
19721127 - 19771127 - 19681126 - 19571109 - 19781128


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:
19721127 - 19771128 - 19871116 - 19571121 - 19571110


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 01 - 05 2014

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  N    A     OREGON      A    A     NRN CALIF   A    A
SRN CALIF   A    A     IDAHO       N    A     NEVADA      A    A
W MONTANA   B    A     E MONTANA   B    A     WYOMING     N    N
UTAH        A    A     ARIZONA     A    A     COLORADO    A    B
NEW MEXICO  A    B     N DAKOTA    B    A     S DAKOTA    B    N
NEBRASKA    N    B     KANSAS      A    B     OKLAHOMA    A    N
N TEXAS     A    A     S TEXAS     A    A     W TEXAS     A    B
MINNESOTA   B    A     IOWA        N    A     MISSOURI    A    A
ARKANSAS    A    A     LOUISIANA   A    A     WISCONSIN   N    A
ILLINOIS    A    A     MISSISSIPPI A    A     MICHIGAN    A    A
INDIANA     A    A     OHIO        A    A     KENTUCKY    A    A
TENNESSEE   A    A     ALABAMA     A    A     NEW YORK    A    A
VERMONT     A    A     NEW HAMP    A    A     MAINE       A    A
MASS        A    A     CONN        A    A     RHODE IS    A    A
PENN        A    A     NEW JERSEY  A    A     W VIRGINIA  A    A
MARYLAND    A    A     DELAWARE    A    A     VIRGINIA    A    A
N CAROLINA  A    A     S CAROLINA  A    A     GEORGIA     A    A
FL PNHDL    A    A     FL PENIN    A    A     AK N SLOPE  N    B
AK ALEUTIAN A    A     AK WESTERN  N    B     AK INT BSN  B    B
AK S INT    B    B     AK SO COAST N    B     AK PNHDL    N    A



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 03 - 09 2014

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  A    A     OREGON      A    A     NRN CALIF   A    B
SRN CALIF   A    N     IDAHO       A    N     NEVADA      A    N
W MONTANA   A    A     E MONTANA   A    B     WYOMING     A    B
UTAH        A    N     ARIZONA     A    A     COLORADO    A    B
NEW MEXICO  A    B     N DAKOTA    N    N     S DAKOTA    N    B
NEBRASKA    A    B     KANSAS      A    B     OKLAHOMA    A    N
N TEXAS     A    N     S TEXAS     A    N     W TEXAS     A    B
MINNESOTA   N    A     IOWA        A    N     MISSOURI    A    N
ARKANSAS    A    A     LOUISIANA   A    A     WISCONSIN   N    A
ILLINOIS    A    A     MISSISSIPPI A    A     MICHIGAN    A    A
INDIANA     A    A     OHIO        A    A     KENTUCKY    A    A
TENNESSEE   A    A     ALABAMA     A    A     NEW YORK    A    A
VERMONT     A    A     NEW HAMP    A    A     MAINE       A    A
MASS        A    A     CONN        A    A     RHODE IS    A    A
PENN        A    A     NEW JERSEY  A    A     W VIRGINIA  A    A
MARYLAND    A    A     DELAWARE    A    A     VIRGINIA    A    A
N CAROLINA  A    A     S CAROLINA  A    A     GEORGIA     A    A
FL PNHDL    A    A     FL PENIN    A    A     AK N SLOPE  N    N
AK ALEUTIAN A    N     AK WESTERN  N    B     AK INT BSN  B    B
AK S INT    N    N     AK SO COAST N    A     AK PNHDL    A    A

                           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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