Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1
000
FXUS06 KWBC 172002
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EST FRI NOVEMBER 17 2017

6-10 DAY OUTLOOK FOR NOV 23 - 27 2017

TODAY`S DYNAMICAL MODEL SOLUTIONS ARE IN GOOD AGREEMENT ON THEIR 500-HPA
CIRCULATION FORECASTS FOR THE 6-10 DAY PERIOD OVER THE NORTH AMERICAN REGION. A
STRONG RIDGE IS FORECAST OVER THE ALEUTIANS, WHILE A TROUGH IS PREDICTED OVER
MUCH OF MAINLAND ALASKA, EXTENDING INTO THE NORTHEAST PACIFIC. ANOTHER TROUGH
IS FORECAST OVER THE EASTERN CONUS WITH A BLOCKING RIDGE OVER THE DAVIS STRAIT.
ABOVE NORMAL 500-HPA HEIGHTS ARE PREDICTED OVER EXTREME SOUTHWESTERN MAINLAND
ALASKA AND ACROSS THE WESTERN TWO-THIRDS OF THE CONUS. BELOW NORMAL 500-HPA
HEIGHTS ARE FORECAST OVER THE REMAINDER OF THE CONUS AND MUCH OF ALASKA.

BELOW NORMAL TEMPERATURES ARE LIKELY FOR MUCH OF ALASKA, UNDER NEGATIVE 500-HPA
HEIGHT ANOMALIES AND OFFSHORE FLOW. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR
PARTS OF WESTERN MAINLAND ALASKA AND THE WESTERN ALEUTIANS, DUE TO ABOVE NORMAL
SEA SURFACE TEMPERATURES IN SURROUNDING AREAS. ABOVE NORMAL TEMPERATURES ARE
MOST LIKELY FOR THE WESTERN HALF OF THE CONUS UNDER PREDICTED ABOVE NORMAL
500-HPA HEIGHTS. BELOW NORMAL TEMPERATURES ARE FAVORED FOR THE EASTERN CONUS
FROM THE LOWER MISSISSIPPI VALLEY AND THE SOUTHEAST U.S. NORTHWARD TO PARTS OF
THE EASTERN GREAT LAKES AND THE NORTHEAST, DUE TO ANOMALOUS NORTHERLY FLOW.

ABOVE NORMAL PRECIPITATION IS FAVORED FOR WESTERN PARTS OF MAINLAND ALASKA, DUE
TO THE FORECAST TROUGH UPSTREAM AND ONSHORE FLOW. BELOW NORMAL PRECIPITATION IS
MOST LIKELY FOR EASTERN REGIONS OF MAINLAND ALASKA, AHEAD OF A PREDICTED RIDGE
AND OFFSHORE FLOW. ABOVE NORMAL PRECIPITATION IS MOST LIKELY FOR CENTRAL AND
NORTHERN CALIFORNIA, NORTHWESTERN NEVADA, THE PACIFIC NORTHWEST, AND THE GREAT
BASIN, EAST OF A PREDICTED TROUGH OVER THE NORTH PACIFIC. ABOVE NORMAL
PRECIPITATION IS FAVORED FOR THE FLORIDA PENINSULA, DUE TO SURFACE LOW
DEVELOPMENT IN THE GULF OF MEXICO. BELOW NORMAL PRECIPITATION IS FORECAST FOR
MOST OF THE REMAINING AREAS OF THE CONUS.

THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 15% OF TODAY`S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 15% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED
ON DAY 8, 10% OF TODAY`S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 8, 5% OF
TODAY`S OPERATIONAL 0Z GFS CENTERED ON DAY 8, 40% OF TODAY`S 0Z EUROPEAN
ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF TODAY`S OPERATIONAL 0Z ECMWF CENTERED ON
DAY 8, AND 10% OF TODAY`S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8


FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
GOOD MODEL AGREEMENT ON THE EXPECTED CIRCULATION PATTERN


8-14 DAY OUTLOOK FOR NOV 25 - DEC 01, 2017

THE OVERALL 500-HPA CIRCULATION PATTERN PREDICTED FOR THE WEEK 2 PERIOD IS
SIMILAR TO THE 6-10 DAY PERIOD ACROSS NORTH AMERICA, BUT THE HIGH AMPLITUDE
RIDGE OVER THE BERING SEA IS FORECAST TO WEAKEN. THE ENSEMBLE SPAGHETTI
DIAGRAMS INDICATE MODERATE TO LARGE SPREAD ACROSS THE MAJORITY OF THE FORECAST
DOMAIN. THE GREATEST WEIGHT FOR THE BLENDED 500-HPA HEIGHT FIELD WAS GIVEN TO
THE ECMWF 0Z ENSEMBLE MEAN BASED ON CONSIDERATIONS OF RECENT SKILL AND ANALOG
CORRELATIONS.

ABOVE NORMAL TEMPERATURES ARE FAVORED FOR PARTS OF THE WESTERN ALEUTIANS AND
PARTS OF NORTHERN MAINLAND ALASKA, DUE TO PREDICTED SOUTHERLY FLOW AND ABOVE
NORMAL SEA SURFACE TEMPERATURES IN SURROUNDING AREAS. ABOVE NORMAL TEMPERATURES
ARE LIKELY FOR THE WESTERN AND CENTRAL CONUS, UNDER PREDICTED ABOVE NORMAL
500-HPA HEIGHTS. BELOW NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF THE
MID-ATLANTIC AND PARTS OF THE SOUTHEAST U.S., ASSOCIATED WITH PREDICTED
ANOMALOUS NORTHERLY FLOW.

A SLIGHT ABOVE NORMAL PRECIPITATION IS TILT IN THE ADDS FOR FORECAST FOR
CENTRAL AND NORTH CALIFORNIA, PARTS OF THE NORTHERN INTERMOUNTAIN EASTWARD TO
NORTHERN PARTS OF THE NORTHERN PLAINS AND THE UPPER MISSISSIPPI VALLEY, AHEAD
OF A PREDICTED TROUGH. BELOW NORMAL PRECIPITATION IS INDICATED FOR MOST OF THE
REMAINING AREAS OF THE CONUS. AREAS OF EASTERN MAINLAND ALASKA ARE PREDICTED TO
HAVE BELOW NORMAL PRECIPITATION, WHILE ABOVE NORMAL PRECIPITATION IS LIKELY FOR
SOUTHWESTERN MAINLAND ALASKA AND THE ALEUTIANS, UNDER PREDICTED ONSHORE AND
CYCLONIC FLOW.

THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 15% OF TODAY`S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 15% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED
ON DAY 11, 15% OF TODAY`S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 11, 5% OF
TODAY`S OPERATIONAL 6Z GFS CENTERED ON DAY 11, 40% OF TODAY`S 0Z EUROPEAN
ENSEMBLE MEAN CENTERED ON DAY 11, AND 10% 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 GOOD AGREEMENT AMONG THE ENSEMBLE MEAN SOLUTIONS ON THE 500-HPA CIRCULATION
PATTERN DURING WEEK 2, OFFSET BY MODERATE TO LARGE SPREAD AMONG THE ENSEMBLE
MEMBERS

FORECASTER: Y. FAN

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 21

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:
19661113 - 19701129 - 19731110 - 19701124 - 19661201


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:
19701127 - 19661113 - 19731110 - 19701122 - 19661130


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR NOV 23 - 27 2017

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



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR NOV 25 - DEC 01, 2017

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

$$




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.