Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1
000
FXUS06 KWBC 191950
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT TUE SEPTEMBER 19 2017

6-10 DAY OUTLOOK FOR SEP 25 - 29 2017

TODAY`S MODELS ARE IN FAIRLY GOOD AGREEMENT ON AN AMPLIFIED FLOW PATTERN OVER
MUCH OF THE FORECAST DOMAIN. HOWEVER, CONFIDENCE IS LOWER ALONG THE EAST COAST
OF THE CONUS DUE TO UNCERTAINTIES SURROUNDING THE EVOLUTION OF HURRICANES JOSE
AND MARIA. A TROUGH IS FORECAST OVER SOUTHWESTERN ALASKA AND A RIDGE IS
EXPECTED DOWNSTREAM NEAR THE ALASKA PANHANDLE SOUTHWARD TO OFF THE PACIFIC
NORTHWEST COAST. TROUGHS ARE PREDICTED OVER THE SOUTHWESTERN CONUS AND THE
NORTHERN PLAINS. ABOVE NORMAL HEIGHTS ARE INDICATED FARTHER TO THE EAST OVER
THE GREAT LAKES AND NORTHEAST. ENSEMBLE SPREAD IS HIGH NEAR THE EAST COAST OF
THE CONUS IN ASSOCIATION WITH THE PREDICTED PATHS OF HURRICANES JOSE AND MARIA.
OFFICIAL NHC GUIDANCE TRANSITIONS JOSE TO A POST-TROPICAL SYSTEM PRIOR TO THE
OUTLOOK PERIOD AND MOST ECMWF AND GFS ENSEMBLE SOLUTIONS KEEP THE REMNANTS OF
JOSE OFFSHORE (ALTHOUGH THE SPREAD OF SOLUTIONS REMAINS HIGH). MEANWHILE,
HURRICANE MARIA IS EXPECTED TO CURVE NORTHWARD OFF THE EAST COAST DURING THE
OUTLOOK PERIOD. WHILE ENSEMBLE MEMBERS FROM THE ECMWF AND GEFS GENERALLY KEEP
THE CENTER OF HURRICANE MARIA OFFSHORE, INTERESTS ALONG THE EAST COAST SHOULD
CONTINUE TO CLOSELY MONITOR THE LATEST UPDATES FROM THE NHC FOR TRACK AND
INTENSITY GUIDANCE AND POTENTIAL IMPACTS. TODAY`S MANUAL 500-HPA HEIGHT BLEND
IS WEIGHTED MOST HEAVILY TOWARD THE 0Z ECMWF ENSEMBLE MEAN SOLUTION BASED
PRIMARILY ON CONSIDERATIONS OF RECENT SKILL.

TROUGHS OVER THE SOUTHWESTERN CONUS AND THE NORTHERN PLAINS TILT THE ODDS TO
BELOW NORMAL TEMPERATURES FOR MUCH OF THE WEST-CENTRAL CONUS. ABOVE NORMAL
TEMPERATURES ARE FAVORED ALONG THE WEST COAST DUE TO AN APPROACHING RIDGE AND
ABOVE NORMAL SSTS. RIDGING AND NEAR TO ABOVE NORMAL HEIGHTS ENHANCE
PROBABILITIES OF ABOVE NORMAL TEMPERATURES FOR THE EASTERN CONUS AND PARTS OF
THE SOUTHERN PLAINS. ABOVE NORMAL HEIGHTS FAVOR ABOVE NORMAL TEMPERATURES FOR
MUCH OF EASTERN AND CENTRAL MAINLAND ALASKA AND THE PANHANDLE. ENHANCED
PROBABILITIES FOR BELOW NORMAL TEMPERATURES ARE INDICATED FOR PARTS OF THE
ALASKA PENINSULA AND ALEUTIANS BEHIND A PREDICTED TROUGH.

THERE ARE ENHANCED PROBABILITIES FOR ABOVE NORMAL PRECIPITATION OVER MUCH OF
THE CENTRAL CONUS IN ASSOCIATION WITH TROUGHS OVER THE SOUTHWESTERN CONUS AND
THE NORTHERN PLAINS. ABOVE NORMAL PRECIPITATION PROBABILITIES ARE HIGHEST FOR
THE SOUTHERN HIGH PLAINS DUE TO POTENTIAL ADVECTION OF TROPICAL MOISTURE EAST
OF THE TROUGH OVER THE SOUTHWESTERN CONUS. BELOW NORMAL PRECIPITATION IS
FAVORED FOR THE NORTHWESTERN CONUS DUE TO EXPECTED RIDGING. THE TROUGH OVER
ALASKA LEADS TO INCREASED ODDS FOR ABOVE NORMAL PRECIPITATION FOR THE ALASKA
PANHANDLE AS WELL AS EASTERN MAINLAND ALASKA. BELOW NORMAL PRECIPITATION IS
FAVORED WEST OF THE TROUGH FOR PARTS OF WESTERN MAINLAND ALASKA AND THE
ALEUTIANS. RIDGING AND NEAR TO ABOVE NORMAL HEIGHTS ENHANCE PROBABILITIES FOR
BELOW NORMAL PRECIPITATION FOR MUCH OF THE EASTERN THIRD OF THE CONUS. ENHANCED
PROBABILITIES FOR NEAR NORMAL PRECIPITATION ARE INDICATED FOR PARTS OF THE
IMMEDIATE MID-ATLANTIC AND NORTHEAST COASTS DUE TO POSSIBLE EFFECTS FROM
HURRICANE MARIA. PROBABILITIES FOR ABOVE NORMAL PRECIPITATION WERE REDUCED
ALONG THE EAST COAST RELATIVE TO YESTERDAY CONSISTENT WITH A MORE OFFSHORE
TRACK. HOWEVER, UNCERTAINTIES ARE HIGH FOR THIS REGION AND PROBABILITIES ARE
SUBJECT TO CHANGE PENDING UPDATED MODEL GUIDANCE.

TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 20% OF TODAY`S 0Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8, 15% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 30%
OF TODAY`S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF YESTERDAY`S 12Z
EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 7, 10% OF TODAY`S OPERATIONAL 0Z ECMWF
CENTERED ON DAY 8, 15% OF TODAY`S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8,
AND 5% OF YESTERDAY`S 12Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 7


FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: BELOW AVERAGE, 2 OUT OF 5, DUE TO
HIGH MODEL SPREAD OVER MUCH OF THE FORECAST DOMAIN AND HIGH UNCERTAINTY ALONG
THE EAST COAST WITH RESPECT TO THE EVOLUTION OF HURRICANES JOSE AND MARIA.

8-14 DAY OUTLOOK FOR SEP 27 - OCT 03, 2017

DURING THE WEEK-2 PERIOD, THE OVERALL 500-HPA FLOW IS FORECAST TO DE-AMPLIFY
AND TRANSITION TO A MORE PROGRESSIVE PATTERN. THE TROUGH OVER THE SOUTHWESTERN
CONUS DURING THE 6 TO 10 DAY PERIOD IS EXPECTED TO LIFT TO THE NORTH AND EAST
AND THE TROUGH OVER THE NORTHERN PLAINS IS PREDICTED TO SHIFT TO THE GREAT
LAKES DURING WEEK-2. BEHIND IT, A RIDGE IS FORECAST TO BUILD OVER THE
NORTHWESTERN CONUS WHILE A TROUGH IS INDICATED OVER WESTERN MAINLAND ALASKA.
FARTHER TO THE SOUTH, SUBTROPICAL RIDGING IS EXPECTED NEAR SOUTHERN TEXAS. MEAN
SURFACE LOW PRESSURE ASSOCIATED WITH MARIA IS GENERALLY FORECAST BY THE ECMWF
AND GFS ENSEMBLE MEANS TO REMAIN OVER THE ATLANTIC OFF THE NORTHEASTERN COAST
OF THE CONUS. HOWEVER, INTERESTS ALONG THE EAST COAST SHOULD CONTINUE TO
MONITOR THE LATEST UPDATES FROM THE NHC REGARDING HURRICANE MARIA DURING THE
WEEK-2 PERIOD.

THERE ARE ENHANCED PROBABILITIES FOR BELOW NORMAL TEMPERATURES FOR PARTS OF THE
CENTRAL CONUS IN ASSOCIATION WITH THE TROUGH OVER THE GREAT LAKES AND THE
WEAKENING TROUGH LIFTING OUT OF THE SOUTHWESTERN CONUS. ABOVE NORMAL
TEMPERATURES ARE FAVORED FARTHER TO THE SOUTH AND EAST FOR MUCH OF THE
SOUTHEASTERN CONUS, THE GULF COAST REGION, AND PARTS FO THE EASTERN SEABOARD.
RIDGING LEADS TO INCREASED ODDS FOR ABOVE NORMAL TEMPERATURES FOR PARTS OF THE
WESTERN CONUS. ABOVE NORMAL TEMPERATURES ARE ALSO FAVORED FOR SOUTHEASTERN
MAINLAND ALASKA AS WELL AS THE ALASKA PANHANDLE UNDERNEATH RIDGING AND EXPECTED
ABOVE NORMAL HEIGHTS. NEAR TO BELOW NORMAL TEMPERATURE PROBABILITIES ARE
ENHANCED FOR PARTS OF WESTERN MAINLAND ALASKA AND THE ALEUTIANS IN ASSOCIATION
WITH A TROUGH OVER WESTERN ALASKA.

THERE ARE ENHANCED PROBABILITIES FOR ABOVE NORMAL PRECIPITATION FOR MOST OF THE
CENTRAL AND SOUTHERN PLAINS, CENTRAL AND SOUTHERN ROCKIES, AND PARTS OF THE
SOUTHWEST IN ASSOCIATION WITH A WEAKENING TROUGH OVER THE SOUTHWESTERN CONUS.
NEAR TO ABOVE NORMAL PRECIPITATION IS FAVORED FOR THE GREAT LAKES AND NORTHEAST
UNDERNEATH CYCLONIC FLOW. ENHANCED PROBABILITIES FOR NEAR NORMAL PRECIPITATION
ARE INDICATED FOR PARTS OF THE NORTHEAST AND MID-ATLANTIC COAST DUE, IN PART,
TO UNCERTAINTIES SURROUNDING THE EVENTUAL PATH OF HURRICANE MARIA.
PROBABILITIES FOR ABOVE NORMAL PRECIPITATION WERE REDUCED FOR THESE AREAS
RELATIVE TO YESTERDAY CONSISTENT WITH A MORE OFFSHORE SOLUTION. ENHANCED
PROBABILITIES FOR BELOW NORMAL PRECIPITATION ARE INDICATED FARTHER TO THE SOUTH
FOR MUCH OF THE SOUTHEASTERN CONUS, CONSISTENT WITH DYNAMICAL MODEL GUIDANCE
FROM THE GEFS AND ECMWF ENSEMBLE MEMBERS. RIDGING LEADS TO FAVORED BELOW NORMAL
PRECIPITATION FOR THE NORTHWESTERN CONUS. THE TROUGH OVER WESTERN ALASKA LEADS
TO INCREASED ODDS FOR ABOVE MEDIAN PRECIPITATION FOR PARTS OF EASTERN MAINLAND
ALASKA AND NORTHERN PARTS OF THE PANHANDLE. BELOW MEDIAN PRECIPITATION IS
FAVORED FOR PARTS OF WESTERN ALASKA UNDERNEATH MEAN EASTERLY FLOW.

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 25% OF TODAY`S 0Z GFS ENSEMBLE
MEAN CENTERED ON DAY 11, 30% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY
11, 10% OF TODAY`S OPERATIONAL 0Z GFS CENTERED ON DAY 11, 25% OF TODAY`S 0Z
EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, 5% OF YESTERDAY`S 12Z EUROPEAN
ENSEMBLE MEAN CENTERED ON DAY 10, AND 5% OF TODAY`S 0Z CANADIAN ENSEMBLE MEAN
CENTERED ON DAY 11


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE
TO A DE-AMPLIFYING PATTERN AS WELL AS HIGH MODEL SPREAD.

FORECASTER: SCOTT H

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
SEPTEMBER 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:
20040914 - 20071001 - 20040919 - 19800831 - 19580922


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:
20040915 - 20071001 - 19580921 - 19600829 - 19590901


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 25 - 29 2017

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



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 27 - OCT 03, 2017

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