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FXUS06 KWBC 201923
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT WED SEPTEMBER 20 2017

6-10 DAY OUTLOOK FOR SEP 26 - 30 2017

TODAY`S ENSEMBLE MEAN SOLUTIONS ARE IN RELATIVELY GOOD AGREEMENT ON A FAIRLY
AMPLIFIED FLOW PATTERN OVER MUCH OF THE FORECAST DOMAIN. HOWEVER, SPREAD AND
UNCERTAINTY ARE HIGH AMONG THE COMPONENT ENSEMBLE MEMBERS OVER MUCH OF THE
COUNTRY. A TROUGH IS FORECAST OVER SOUTHWESTERN MAINLAND ALASKA AND A RIDGE IS
EXPECTED TO BUILD DOWNSTREAM OVER THE NORTHWESTERN CONUS. TROUGHS ARE PREDICTED
OVER THE SOUTHWESTERN CONUS AND THE UPPER MISSISSIPPI VALLEY. ENSEMBLE SPREAD
IS HIGH NEAR THE EAST COAST OF THE CONUS IN ASSOCIATION WITH THE PREDICTED
PATHS OF TROPICAL STORM JOSE AND HURRICANE 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 CLOSE TO THE MID ATLANTIC OR NORTHEAST COAST DURING THE
OUTLOOK PERIOD. INTERESTS ALONG THE EAST COAST ARE STRONGLY ENCOURAGED 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 A BUILDING RIDGE AND
ABOVE NORMAL SSTS. ENHANCED PROBABILITIES OF ABOVE NORMAL TEMPERATURES ARE
INDICATED FOR THE EASTERN CONUS AND PARTS OF THE SOUTHERN PLAINS TO THE EAST OF
THE TROUGHS OVER THE SOUTHWEST AND UPPER MISSISSIPPI VALLEY. 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 ALEUTIANS BEHIND A PREDICTED TROUGH.

THERE ARE ENHANCED PROBABILITIES FOR ABOVE NORMAL PRECIPITATION OVER MUCH OF
THE SOUTH-CENTRAL CONUS AND PARTS OF THE SOUTHWEST IN ASSOCIATION WITH A TROUGH
OVER THE SOUTHWESTERN CONUS AND THE POTENTIAL ADVECTION OF TROPICAL MOISTURE
INTO THE REGION. BELOW NORMAL PRECIPITATION IS FAVORED FOR THE NORTHWESTERN
CONUS DUE TO EXPECTED RIDGING. THERE ARE INCREASED ODDS FOR ABOVE NORMAL
PRECIPITATION FOR PARTS OF THE WESTERN GREAT LAKES AND UPPER MISSISSIPPI VALLEY
UNDERNEATH CYCLONIC FLOW. THE TROUGH OVER ALASKA LEADS TO INCREASED ODDS FOR
ABOVE NORMAL PRECIPITATION FOR EASTERN MAINLAND ALASKA AND THE ALASKA
PANHANDLE. BELOW NORMAL PRECIPITATION IS FAVORED WEST OF THE TROUGH FOR PARTS
OF WESTERN MAINLAND ALASKA AND THE ALEUTIANS. BELOW NORMAL PRECIPITATION IS
FAVORED FOR MUCH OF THE SOUTHEASTERN CONUS IN ASSOCIATION WITH SUBTROPICAL
RIDGING OVER THE WESTERN GULF OF MEXICO AND CONSISTENT WITH CALIBRATED
PRECIPITATION GUIDANCE FROM THE ECMWF AND GFS ENSEMBLES.

ENHANCED PROBABILITIES FOR ABOVE NORMAL PRECIPITATION ARE INDICATED FOR PARTS
OF THE NORTHEAST AND MID-ATLANTIC COAST DUE TO POSSIBLE EFFECTS FROM HURRICANE
MARIA. PROBABILITIES FOR ABOVE NORMAL PRECIPITATION WERE INCREASED FOR THESE
REGIONS RELATIVE TO YESTERDAY AS THE RANGE OF SOLUTIONS FROM TODAY`S DYNAMICAL
MODEL GUIDANCE FROM THE GEFS AND ECMWF ENSEMBLES INDICATE THE POTENTIAL FOR A
CLOSE ENOUGH APPROACH FROM HURRICANE MARIA FOR PRECIPITATION IMPACTS.
UNCERTAINTIES ARE HIGH FOR THIS REGION AND PROBABILITIES ARE SUBJECT TO CHANGE
PENDING UPDATED MODEL GUIDANCE.

TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 15% OF TODAY`S 0Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8, 25% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF
TODAY`S OPERATIONAL 0Z GFS 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, 5% OF TODAY`S OPERATIONAL 0Z ECMWF CENTERED ON DAY 8, 5% OF
YESTERDAY`S OPERATIONAL 12Z ECMWF CENTERED ON DAY 7, AND 10% OF TODAY`S 0Z
CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8


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 TROPICAL STORM JOSE AND
HURRICANE MARIA.

8-14 DAY OUTLOOK FOR SEP 28 - OCT 04, 2017

DURING THE WEEK-2 PERIOD, THE OVERALL 500-HPA FLOW PATTERN IS GENERALLY
FORECAST TO PROGRESS EASTWARD. THE TROUGH OVER THE SOUTHWESTERN CONUS DURING
THE 6 TO 10 DAY PERIOD IS EXPECTED TO WEAKEN AND LIFT TO THE NORTH AND EAST AND
THE TROUGH OVER THE UPPER MISSISSIPPI VALLEY IS PREDICTED TO SHIFT TO THE GREAT
LAKES DURING WEEK-2. BEHIND IT, A RIDGE IS FORECAST TO CONTINUE TO BUILD OVER
THE WESTERN CONUS WHILE A TROUGH IS INDICATED OVER WESTERN MAINLAND ALASKA.
FARTHER TO THE SOUTH, SUBTROPICAL RIDGING IS EXPECTED NEAR SOUTHERN TEXAS.
SURFACE LOW PRESSURE ASSOCIATED WITH HURRICANE MARIA IS GENERALLY FORECAST BY
THE ECMWF AND GFS ENSEMBLE MEANS TO BE CLOSE TO THE NORTHEASTERN OR
MID-ATLANTIC COAST OF THE CONUS AT THE BEGINNING OF THE PERIOD. 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 NEAR TO BELOW NORMAL TEMPERATURES FOR THE
SOUTH-CENTRAL CONUS IN ASSOCIATION WITH A WEAKENING TROUGH. THE TROUGH OVER THE
GREAT LAKES LEADS TO INCREASED ODDS FOR NEAR TO BELOW NORMAL TEMPERATURES FOR
THE NORTHEASTERN QUARTER OF THE CONUS. ABOVE NORMAL TEMPERATURES ARE FAVORED
FARTHER TO THE SOUTH AND EAST FOR PARTS OF THE SOUTHEASTERN CONUS. RIDGING
LEADS TO INCREASED ODDS FOR ABOVE NORMAL TEMPERATURES FOR MUCH OF THE WESTERN
CONUS. ABOVE NORMAL TEMPERATURES ARE ALSO FAVORED FOR THE ALASKA PANHANDLE AND
MUCH OF MAINLAND ALASKA UNDERNEATH EXPECTED NEAR TO ABOVE NORMAL HEIGHTS.

THERE ARE ENHANCED PROBABILITIES FOR ABOVE NORMAL PRECIPITATION FOR MOST OF THE
SOUTHERN HIGH PLAINS, CENTRAL AND SOUTHERN ROCKIES, AND PARTS OF THE SOUTHWEST
IN ASSOCIATION WITH A WEAKENING TROUGH. ABOVE NORMAL PRECIPITATION IS FAVORED
FOR PARTS OF THE NORTHEAST IN ASSOCIATION WITH A TROUGH OVER THE GREAT LAKES
AND POTENTIAL MOISTURE FROM HURRICANE MARIA. MEAN SURFACE HIGH PRESSURE LEADS
TO ENHANCED PROBABILITIES FOR BELOW NORMAL PRECIPITATION FARTHER TO THE SOUTH
AND WEST FOR MUCH OF THE MISSISSIPPI AND OHIO VALLEYS. CHANCES FOR ABOVE NORMAL
PRECIPITATION ARE ELEVATED FOR PARTS OF SOUTHERN FLORIDA UNDERNEATH BELOW
NORMAL HEIGHTS AND DUE TO POTENTIAL INFLUXES OF TROPICAL MOISTURE LATER IN THE
PERIOD. RIDGING FAVORS BELOW NORMAL PRECIPITATION FOR THE NORTHWESTERN CONUS.
THE TROUGH OVER WESTERN ALASKA LEADS TO INCREASED ODDS FOR ABOVE NORMAL
PRECIPITATION FOR PARTS OF EASTERN MAINLAND ALASKA AND NORTHERN PARTS OF THE
PANHANDLE. BELOW NORMAL 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, 20% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY
11, 5% OF TODAY`S OPERATIONAL 6Z GFS CENTERED ON DAY 11, 35% OF TODAY`S 0Z
EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, 5% OF YESTERDAY`S 12Z EUROPEAN
ENSEMBLE MEAN CENTERED ON DAY 10, AND 10% 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 POTENTIAL PATTERN SHIFT AND DUE TO 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:
20040917 - 19770922 - 19680917 - 19860924 - 19800831


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:
20040916 - 19970914 - 19860926 - 19680917 - 19770920


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 26 - 30 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       N    B     NEVADA      N    B
W MONTANA   N    B     E MONTANA   N    B     WYOMING     B    B
UTAH        B    N     ARIZONA     B    A     COLORADO    B    A
NEW MEXICO  B    A     N DAKOTA    N    B     S DAKOTA    B    B
NEBRASKA    B    N     KANSAS      B    A     OKLAHOMA    B    A
N TEXAS     A    A     S TEXAS     A    A     W TEXAS     B    A
MINNESOTA   N    N     IOWA        N    N     MISSOURI    A    N
ARKANSAS    A    N     LOUISIANA   A    B     WISCONSIN   A    A
ILLINOIS    A    B     MISSISSIPPI A    B     MICHIGAN    A    N
INDIANA     A    B     OHIO        A    B     KENTUCKY    A    B
TENNESSEE   A    B     ALABAMA     A    B     NEW YORK    A    N
VERMONT     A    A     NEW HAMP    A    A     MAINE       A    A
MASS        A    A     CONN        A    A     RHODE IS    A    A
PENN        A    N     NEW JERSEY  A    N     W VIRGINIA  A    B
MARYLAND    A    N     DELAWARE    A    N     VIRGINIA    A    N
N CAROLINA  A    N     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    A
AK S INT    A    A     AK SO COAST A    A     AK PNHDL    A    A



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 28 - OCT 04, 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   A    B     WYOMING     A    B
UTAH        A    N     ARIZONA     A    A     COLORADO    N    A
NEW MEXICO  B    A     N DAKOTA    A    B     S DAKOTA    N    B
NEBRASKA    N    N     KANSAS      B    N     OKLAHOMA    B    N
N TEXAS     B    A     S TEXAS     B    A     W TEXAS     B    A
MINNESOTA   N    B     IOWA        B    B     MISSOURI    B    B
ARKANSAS    B    B     LOUISIANA   N    N     WISCONSIN   N    B
ILLINOIS    B    B     MISSISSIPPI N    B     MICHIGAN    N    B
INDIANA     B    B     OHIO        B    B     KENTUCKY    B    B
TENNESSEE   B    B     ALABAMA     N    B     NEW YORK    N    N
VERMONT     N    A     NEW HAMP    N    A     MAINE       N    A
MASS        N    A     CONN        N    N     RHODE IS    N    A
PENN        N    B     NEW JERSEY  N    N     W VIRGINIA  N    B
MARYLAND    N    N     DELAWARE    N    N     VIRGINIA    N    N
N CAROLINA  A    N     S CAROLINA  A    N     GEORGIA     A    N
FL PNHDL    A    N     FL PENIN    A    N     AK N SLOPE  A    A
AK ALEUTIAN N    B     AK WESTERN  A    B     AK INT BSN  A    A
AK S INT    A    A     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.

$$




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