Prognostic Meteorological Discussion
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FXUS06 KWBC 161915
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT MON OCTOBER 16 2017

6-10 DAY OUTLOOK FOR OCT 22 - 26 2017

TODAY`S ENSEMBLE MEAN SOLUTIONS ARE IN RELATIVELY GOOD AGREEMENT ON AN
AMPLIFIED FLOW PATTERN OVER MOST OF THE FORECAST DOMAIN. A DEEP CLOSED 500-HPA
TROUGH IS FORECAST OVER PARTS OF WESTERN ALASKA, WITH NEGATIVE HEIGHT ANOMALIES
EXTENDING SOUTHWARD TO HAWAII. DOWNSTREAM A STRONG RIDGE IS PREDICTED OVER THE
WESTERN HALF OF THE CONUS. A TROUGH IS FORECAST OVER THE EASTERN HALF OF THE
CONUS. TODAYS 500-HPA MANUAL BLEND FEATURES NEGATIVE HEIGHT ANOMALIES OVER ALL
OF ALASKA, AND ABOVE NORMAL HEIGHTS OVER THE REST OF THE U.S., EXCEPT FOR
SLIGHTLY NEGATIVE HEIGHT ANOMALIES FOR PARTS OF THE GREAT LAKES REGION.

NEAR TO BELOW NORMAL TEMPERATURES ARE FAVORED FOR ALASKA DUE TO A DEEP TROUGH
PREDICTED OVER MUCH OF ALASKA. A STRONG RIDGE PREDICTED OVER THE WESTERN CONUS
HIGHLY FAVORS ABOVE NORMAL TEMPERATURES FOR MOST OF THE WESTERN U.S., EXCEPT
FOR PARTS OF TEXAS WHERE NEGATIVE TEMPERATURE ANOMALIES ARE FORECAST TO PERSIST
AFTER AN EXPECTED FRONTAL PASSAGE DURING THE PERIOD.

STORM SYSTEM ACTIVITY IS FORECAST TO TRAVEL AROUND THE CLOSED LOW OVER PARTS OF
ALASKA, INCREASING THE LIKELIHOOD FOR ABOVE NORMAL PRECIPITATION FROM THE
ALEUTIANS AND THE SOUTHERN ALASKA COAST TO THE PACIFIC NORTHWEST. THE WESTERN
RIDGE IS FORECAST TO CONTAIN THE SYSTEMS TO JUST THE PACIFIC NORTHWEST WITHIN
THE CONUS, FAVORING BELOW NORMAL PRECIPITATION OVER MUCH OF THE REST OF THE
WESTERN HALF OF THE CONUS. A FRONTAL SYSTEM ASSOCIATED WITH THE TROUGH
PREDICTED IN THE EASTERN U.S. INCREASES THE CHANCES FOR ABOVE NORMAL
PRECIPITATION FOR MUCH OF THE EASTERN HALF OF THE CONUS.

TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 50% OF TODAY`S 6Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8, AND 50% OF TODAY`S OPERATIONAL 0Z ECMWF CENTERED ON DAY 8


FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
GOOD AGREEMENT AMONG THE ENSEMBLE MEANS AND TOOLS, OFFSET BY SOME LARGE-SCALE
DIFFERENCES AMONG THE DETERMINISTIC MODEL RUNS

8-14 DAY OUTLOOK FOR OCT 24 - 30 2017

DURING THE WEEK-2 PERIOD, THE OVERALL 500-HPA FLOW PATTERN IS EXPECTED TO
RETROGRADE SLIGHTLY, AND THE EASTERN TROUGH IS EXPECTED TO INTENSIFY.

THE TEMPERATURE PROBABILITIES FORECAST DURING THE 6-10 DAY PERIOD ARE SIMILAR
TO THOSE FORECAST DURING THE WEEK-2 PERIOD, WITH A FEW EXCEPTIONS. SOME RIDGING
IS EXPECTED TO BUILD WESTWARD INTO EASTERN PORTIONS OF ALASKA, FAVORING ABOVE
NORMAL TEMPERATURES THERE. THE DEEPENING TROUGH IN THE EASTERN U.S. INCREASES
THE LIKELIHOOD OF NEAR TO BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE EASTERN
U.S.

THE PRECIPITATION PROBABILITIES FORECAST DURING THE 6-10 DAY PERIOD ARE SIMILAR
TO THE WEEK-2 PERIOD, WITH SOME EXCEPTIONS. AS THE WESTERN RIDGE IS FORECAST TO
RETROGRADE, ITS EXPECTED TO SUPPRESS STORM SYSTEM ACTIVITY IN THE PACIFIC
NORTHWEST, ENHANCING THE LIKELIHOOD OF BELOW NORMAL PRECIPITATION THERE. A
FRONTAL SYSTEM FORECAST TO TRAVEL ACROSS THE EASTERN U.S. DURING THE 6-10 DAY
PERIOD IS FORECAST TO BE NEAR THE COAST BY THE BEGINNING OF THE WEEK-2 PERIOD,
SHIFTING THE AREA OF FAVORED ABOVE NORMAL PRECIPITATION TO THE APPALACHIANS AND
EASTWARD BY THE WEEK-2 PERIOD. THE SURFACE LOW ASSOCIATED WITH THIS SYSTEM IS
FORECAST TO PERSIST IN THE GREAT LAKES, PERSISTING THE AREA OF FAVORED ABOVE
NORMAL PRECIPITATION FOR PARTS OF THE GREAT LAKES REGION.

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 30% OF TODAY`S 0Z GFS ENSEMBLE
MEAN CENTERED ON DAY 11, 30% OF YESTERDAY`S OPERATIONAL 18Z GFS CENTERED ON DAY
10, AND 40% OF TODAY`S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: AVERAGE, 3 OUT OF 5, DUE TO
GOOD MODEL AGREEMENT, OFFSET BY SOME DIFFERENCES IN THE TOOLS, ESPECIALLY DUE
TO A TEMPERATURE TRANSITION IN THE EASTERN U.S.

FORECASTER: MIKE C

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
OCTOBER 19

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:
19901008 - 20070926 - 20011020 - 19891012 - 19811025


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:
19901009 - 20050926 - 19811025 - 20011019 - 19851012


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 22 - 26 2017

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  A    A     OREGON      A    B     NRN CALIF   A    B
SRN CALIF   A    N     IDAHO       A    B     NEVADA      A    B
W MONTANA   A    B     E MONTANA   A    B     WYOMING     A    B
UTAH        A    B     ARIZONA     A    B     COLORADO    A    B
NEW MEXICO  A    B     N DAKOTA    A    B     S DAKOTA    A    B
NEBRASKA    A    B     KANSAS      A    B     OKLAHOMA    A    A
N TEXAS     A    A     S TEXAS     N    A     W TEXAS     A    B
MINNESOTA   A    B     IOWA        A    N     MISSOURI    A    A
ARKANSAS    A    A     LOUISIANA   A    A     WISCONSIN   A    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    N     NEW HAMP    A    N     MAINE       A    N
MASS        A    N     CONN        A    N     RHODE IS    A    N
PENN        A    A     NEW JERSEY  A    N     W VIRGINIA  A    A
MARYLAND    A    N     DELAWARE    A    N     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 B    A     AK WESTERN  B    A     AK INT BSN  N    N
AK S INT    B    A     AK SO COAST B    A     AK PNHDL    B    A



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 24 - 30 2017

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