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FXUS06 KWBC 181944
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT MON SEPTEMBER 18 2017

6-10 DAY OUTLOOK FOR SEP 24 - 28 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 MAINLAND ALASKA AND A DEEP, POSITIVELY
TILTED TROUGH IS PREDICTED OVER OVER MUCH OF THE WESTERN CONUS. RIDGING AND
ABOVE NORMAL HEIGHTS ARE INDICATED DOWNSTREAM 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. MOST ECMWF
AND GFS ENSEMBLE SOLUTIONS CURVE JOSE OUT TO SEA PRIOR TO THE PERIOD BUT A
SUBSET OF ENSEMBLE MEMBERS THEN RE-CURVE IT CLOSER TO THE MID ATLANTIC COAST
NEAR THE BEGINNING OF THE PERIOD AS A WEAKER SYSTEM. MEANWHILE, MOST ENSEMBLE
MEMBERS FROM THE ECMWF AND THE GFS CURVE MARIA NORTHWARD CLOSE TO THE EAST
COAST DURING THE OUTLOOK PERIOD. INTERESTS ALONG THE EAST COAST SHOULD CLOSELY
MONITOR THE LATEST UPDATES FROM THE NHC FOR TRACK AND INTENSITY GUIDANCE AND
POTENTIAL IMPACTS FROM BOTH MARIA AND JOSE. 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.

THE TROUGH OVER THE WESTERN CONUS TILTS THE ODDS TO BELOW NORMAL TEMPERATURES
FOR MUCH OF THE INTERIOR WEST, EXTENDING TO MUCH OF THE NORTHERN AND CENTRAL
PLAINS AND PARTS OF THE SOUTHERN HIGH PLAINS. HOWEVER, ABOVE NORMAL
TEMPERATURES ARE SLIGHTLY FAVORED ALONG PASTS OF THE CALIFORNIA COAST DUE, IN
PART, TO ABOVE NORMAL SSTS. RIDGING AND NEAR TO ABOVE NORMAL HEIGHTS AHEAD OF
THE TROUGH ENHANCE PROBABILITIES OF ABOVE NORMAL TEMPERATURES FOR THE EASTERN
CONUS AND MUCH 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 EASTERN ALEUTIANS BEHIND A PREDICTED TROUGH.

THERE ARE ENHANCED PROBABILITIES FOR ABOVE NORMAL PRECIPITATION OVER MUCH OF
THE CENTRAL CONUS EAST OF THE TROUGH OVER THE WESTERN CONUS. BELOW NORMAL
PRECIPITATION IS FAVORED WEST OF THE TROUGH AXIS FOR THE NORTHWESTERN CONUS.
THE TROUGH OVER ALASKA LEADS TO INCREASED ODDS FOR ABOVE NORMAL PRECIPITATION
FOR THE ALASKA PANHANDLE AS WELL AS EASTERN AND CENTRAL MAINLAND ALASKA. NEAR
TO BELOW NORMAL PRECIPITATION IS FAVORED BEHIND THE TROUGH FOR EXTREME
SOUTHWESTERN MAINLAND ALASKA, THE ALASKA PENINSULA, AND THE EASTERN ALEUTIANS.
RIDGING AND NEAR TO ABOVE NORMAL HEIGHTS ENHANCE PROBABILITIES FOR BELOW NORMAL
PRECIPITATION FROM PARTS OF THE GULF COAST NORTHWARD TO THE INTERIOR NORTHEAST.
ENHANCED PROBABILITIES FOR NEAR TO ABOVE NORMAL PRECIPITATION ARE INDICATED FOR
PARTS OF THE EAST COAST DUE TO POTENTIAL EFFECTS FROM HURRICANES JOSE AND
MARIA. UNCERTAINTIES ARE HIGH FOR THIS REGION AND PROBABILITIES ARE SUBJECT TO
CHANGE PENDING UPDATED MODEL GUIDANCE.

TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 10% OF TODAY`S 0Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8, 10% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF
TODAY`S OPERATIONAL 6Z GFS CENTERED ON DAY 8, 40% OF TODAY`S 0Z EUROPEAN
ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF YESTERDAY`S 12Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 7, 25% 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: ABOUT AVERAGE, 3 OUT OF 5, DUE TO
GOOD MODEL AGREEMENT ON AN AMPLIFIED FLOW PATTERN OVER MUCH OF THE FORECAST
DOMAIN OFFSET BY HIGH UNCERTAINTY ALONG THE EAST COAST WITH RESPECT TO
HURRICANES JOSE AND MARIA.

8-14 DAY OUTLOOK FOR SEP 26 - OCT 02, 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 WESTERN CONUS
DURING THE 6 TO 10 DAY PERIOD IS EXPECTED TO SHIFT EASTWARD TO THE NORTHERN
PLAINS/WESTERN 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 FOR
PORTIONS OF THE SOUTHERN PLAINS. A WEAKNESS IN THE SUBTROPICAL RIDGE IS
PREDICTED NEAR THE EAST COAST AND UNCERTAINTY REMAINS ELEVATED AS TO THE
EVOLUTION OF HURRICANE MARIA INTO THE WEEK-2 TIME PERIOD. MEAN SURFACE LOW
PRESSURE ASSOCIATED WITH MARIA IS FORECAST BY THE ECMWF OR GFS ENSEMBLE MEANS
OFF THE MID ATLANTIC OR NORTHEAST COAST. INTERESTS ALONG THE EAST COAST SHOULD
CONTINUE TO MONITOR THE LATEST UPDATES REGARDING HURRICANE MARIA DURING THE
WEEK-2 PERIOD.

THERE ARE ENHANCED PROBABILITIES FOR BELOW NORMAL TEMPERATURES FOR MUCH OF THE
CENTRAL CONUS IN ASSOCIATION WITH THE TROUGH OVER THE NORTHERN PLAINS / GREAT
LAKES. NEAR TO ABOVE NORMAL TEMPERATURES ARE FAVORED AHEAD OF THIS TROUGH FOR
MUCH OF THE EASTERN CONUS AND GULF COAST REGION. RIDGING LEADS TO INCREASED
ODDS FOR ABOVE NORMAL TEMPERATURES FOR THE WEST COAST OF THE CONUS. ABOVE
NORMAL TEMPERATURES ARE ALSO FAVORED FOR PARTS OF EASTERN MAINLAND ALASKA AS
WELL AS THE ALASKA PANHANDLE UNDERNEATH EXPECTED ABOVE NORMAL HEIGHTS. NEAR TO
BELOW NORMAL TEMPERATURE PROBABILITIES ARE ENHANCED FOR PARTS OF CENTRAL AND
WESTERN MAINLAND ALASKA AND THE ALEUTIANS IN ASSOCIATION WITH A TROUGH OVER
WESTERN ALASKA.

THERE ARE ENHANCED PROBABILITIES FOR ABOVE NORMAL PRECIPITATION FOR MUCH OF THE
SOUTH-CENTRAL CONUS EXTENDING TO THE WESTERN GREAT LAKES UNDERNEATH CYCLONIC
FLOW. ABOVE NORMAL PRECIPITATION IS FAVORED FOR PARTS OF THE NORTHEAST AND
MID-ATLANTIC EAST OF THE TROUGH OVER THE NORTH-CENTRAL CONUS AND ALSO DUE TO
POTENTIAL EFFECTS FROM HURRICANE MARIA. 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 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: 5% 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, 40% OF TODAY`S 0Z
EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, 5% OF YESTERDAY`S 12Z EUROPEAN
ENSEMBLE MEAN CENTERED ON DAY 10, 5% OF TODAY`S 0Z CANADIAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 5% OF YESTERDAY`S 12Z CANADIAN ENSEMBLE MEAN CENTERED
ON DAY 10


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE
TO A DE-AMPLIFYING PATTERN AS WELL AS UNCERTAINTIES SURROUNDING THE EVOLUTION
OF HURRICANE MARIA.

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:
20040912 - 20070930 - 19990904 - 19580922 - 20070925


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:
20040913 - 20070927 - 20040918 - 19780917 - 19580921


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 24 - 28 2017

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  N    B     OREGON      N    B     NRN CALIF   A    N
SRN CALIF   B    N     IDAHO       B    B     NEVADA      B    B
W MONTANA   B    N     E MONTANA   B    A     WYOMING     B    A
UTAH        B    N     ARIZONA     B    N     COLORADO    B    A
NEW MEXICO  B    A     N DAKOTA    B    A     S DAKOTA    B    A
NEBRASKA    B    A     KANSAS      B    A     OKLAHOMA    A    A
N TEXAS     A    A     S TEXAS     A    A     W TEXAS     N    A
MINNESOTA   N    A     IOWA        A    A     MISSOURI    A    A
ARKANSAS    A    A     LOUISIANA   A    N     WISCONSIN   A    A
ILLINOIS    A    A     MISSISSIPPI A    N     MICHIGAN    A    A
INDIANA     A    N     OHIO        A    B     KENTUCKY    A    B
TENNESSEE   A    B     ALABAMA     A    B     NEW YORK    A    B
VERMONT     A    N     NEW HAMP    A    N     MAINE       A    N
MASS        A    N     CONN        A    N     RHODE IS    A    N
PENN        A    B     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  A    A
AK ALEUTIAN B    B     AK WESTERN  N    N     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 26 - OCT 02, 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       N    B     NEVADA      N    B
W MONTANA   N    B     E MONTANA   B    N     WYOMING     B    N
UTAH        B    B     ARIZONA     N    N     COLORADO    B    A
NEW MEXICO  B    A     N DAKOTA    B    N     S DAKOTA    B    N
NEBRASKA    B    A     KANSAS      B    A     OKLAHOMA    B    A
N TEXAS     N    A     S TEXAS     A    A     W TEXAS     B    A
MINNESOTA   B    A     IOWA        B    A     MISSOURI    N    A
ARKANSAS    N    A     LOUISIANA   A    N     WISCONSIN   N    A
ILLINOIS    N    A     MISSISSIPPI A    B     MICHIGAN    N    A
INDIANA     N    A     OHIO        A    N     KENTUCKY    A    N
TENNESSEE   A    N     ALABAMA     A    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    N     NEW JERSEY  A    A     W VIRGINIA  A    N
MARYLAND    A    A     DELAWARE    A    A     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    N     AK WESTERN  N    B     AK INT BSN  N    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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