Prognostic Meteorological Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4
000
FXUS06 KWBC 041901
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT FRI SEPTEMBER 04 2015

6-10 DAY OUTLOOK FOR SEP 10 - 14 2015

TODAY`S MODEL SOLUTIONS ARE IN ONLY FAIR AGREEMENT ON THE PREDICTED 500-HPA
FLOW PATTERN OVER NORTH AMERICA AND VICINITY. THE ENSEMBLE MEAN SOLUTIONS FROM
THE GFS AND ECMWF MODELS INDICATE TROUGHS OVER ALASKA AND THE EASTERN CONUS. A
RIDGE IS EXPECTED TO BE APPROACHING THE WEST COAST. RECENT CANADIAN ENSEMBLE
MEAN SOLUTIONS INDICATE A LOW AMPLITUDE ZONAL FLOW PATTERN ACROSS THE CONUS,
AND THE TROUGH FOR ALASKA BEING FURTHER WEST, COMPARED TO THE ECMWF AND GFS
ENSEMBLE MEAN SOLUTIONS. THE LATEST HIGH RESOLUTION GFS AND ECMWF FORECASTS
INDICATE THE HIGHER AMPLITUDE FLOW PATTERN RELECTED IN THEIR RESPECTIVE
ENSEMBLE MEANS. THE ENSEMBLE SPAGHETTI CHARTS INDICATE MODERATE SPREAD ACROSS
MOST OF THE FORECAST DOMAIN. THE GFS AND ECMWF SPAGHETTI CHARTS ARE IN FAIRLY
GOOD AGREEMENT IN DEPICTING A TROUGH OVER THE EASTERN CONUS, ALTHOUGH AMPLITUDE
DIFFERENCES ARE APPARENT. THE CANADIAN SPAGHETTI CHARTS SHOW LARGER SPREAD AND
ARE NOT IN AS GOOD AGREEMENT REGARDING THE TROUGH EXPECTED OVER THE EAST. THE
CANADIAN SOLUTIONS WERE NOT INCLUDED IN TODAYS 500-HPA BLEND CHART. TODAY`S
HEIGHT BLEND DEPICTS NEAR TO BELOW NORMAL HEIGHTS OVER MOST OF THE CENTRAL AND
EASTERN CONUS, AND ALASKA, AND NEAR TO ABOVE NORMAL HEIGHTS OVER THE WESTERN
CONUS, THE NORTHEAST, AND SOUTHERN FLORIDA. EXPECTED HEIGHT ANOMALIES FOR THE
6-10 DAY PERIOD TODAY ARE IN GENERAL LARGER THAN IN RECENT DAYS.

BELOW NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF THE CENTRAL CONUS IN
ASSOCIATION WITH THE AREA OF NEAR TO BELOW NORMAL HEIGHTS ANTICIPATED OVER THE
REGION. ABOVE NORMAL TEMPERATURES ARE FAVORED OVER MOST OF THE EASTERN CONUS
(DUE TO WEAK ANOMALOUS SOUTHERLY FLOW AHEAD OF THER CENTRAL U.S. TROUGH) AND
THE WESTERN CONUS (DUE TO ABOVE NORMAL HEIGHTS AND ABOVE NORMAL SST`S FOR
ADJACENT WATERS). ANOMALOUS NORTHERLY FLOW AND BELOW NORMAL HEIGHTS TILT THE
ODDS TO BELOW NORMAL TEMPERATURES FOR MOST OF ALASKA.

THERE ARE ENHANCED PROBABILITIES OF ABOVE MEDIAN PRECIPITATION FOR MUCH OF THE
CENTRAL AND EASTERN CONUS DUE TO THE TROUGH EXPECTED OVER THE EAST-CENTRAL
CONUS. ABOVE NORMAL HEIGHTS AND ANOMALOUS NORTHERLY FLOW ENHANCE PROBABILITIES
FOR BELOW MEDIAN PRECIPITATION FOR THE NORTHWESTERN AND NORTH-CENTRAL CONUS.
ANOMALOUS NORTHEASTERLY FLOW TILTS THE ODDS TO BELOW MEDIAN PRECIPITATION FOR
MOST OF WESTERN ALASKA AND THE ALEUTIANS.  ABOVE NORMAL HEIGHTS ENHANCE
PROBABILITIES FOR BELOW MEDIAN PRECIPITATION FOR SOUTHERN FLORIDA. THE TROUGH
PREDICTED OVER ALASKA TILTS THE ODDS TO ABOVE MEDIAN PRECIPITATION FOR
SOUTHEASTERN ALASKA AND THE ALASKA PANHANDLE.

TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 25% OF TODAY`S 0Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8, 30% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF
TODAY`S OPERATIONAL 0Z GFS CENTERED ON DAY 8, 25% OF TODAY`S 0Z EUROPEAN
ENSEMBLE MEAN CENTERED ON DAY 8, 10% OF YESTERDAY`S 12Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 7, AND 5% OF TODAY`S OPERATIONAL 0Z ECMWF CENTERED ON DAY 8


FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOUT AVERAGE, 3 OUT OF 5, DUE TO
FAIR AGREEMENT AMONG THE MODEL SOLUTIONS AND MODERATE SPREAD AMONG THE ENSEMBLE
MEMBERS.



8-14 DAY OUTLOOK FOR SEP 12 - 18 2015

TODAY`S WEEK-2 MODEL SOLUTIONS CONTINUE TO EXHIBIT RELATIVELY LARGE SPREAD AND
UNCERTAINTY FOR MUCH OF THE FORECAST DOMAIN, ALTHOUGH THERE IS FAIRLY GOOD
AGREEMENT THAT A TROUGH WILL BE LOCATED OVER THE EAST-CENTRAL CONUS, ESPECIALLY
FOR THE GFS ENSEMBLE MEMBERS. OVERALL THE EXPECTED FLOW PATTERN FOR WEEK-2 IS
NOT SUBSTANTIALLY DIFFERENT FROM THAT PREDICTED FOR THE 6-10 DAY PERIOD,
ALTHOUGH THE CANADIAN SOLUTIONS CONTINUE TO DIFFER SUBSTANIALLY FROM THE GFS
AND ECMWF ENSEMBLE PREDICTIONS. THE TROUGH FORECAST OVER ALASKA IS EXPECTED TO
RETROGRADE DURING THE WEEK-2 PERIOD. THE BLENDED HEIGHT CHART INDICATES NEAR TO
BELOW NORMAL HEIGHTS OVER THE EASTERN AND CENTRAL CONUS (EXCEPT FOR THE
NOTHEAST) AND ALASKA, WHILE NEAR TO ABOVE NORMAL HEIGHTS ARE ANTICIPATED
ELSEWHERE.

THE EXPECTED TEMPERATURE AND PRECIPITATION ANOMALY PATTERNS FOR WEEK-2 ARE NOT
SUBSTANTIALLY DIFFERENT FROM THOSE FORECAST FOR THE 6-10 DAY PERIOD. THIS IS
NOT SURPRISING GIVEN HOW LITTLE THE OVERALL CIRCULATION PATTERN IS FORECAST TO
CHANGE BETWEEN THE TWO FORECAST PERIODS. THE AREA OF BELOW (ABOVE) NORMAL
TEMPERATURES EXPECTED OVER THE CENTRAL CONUS EXPANDS (CONTRACTS) EASTWARD
DURING WEEK 2. AS THE TROUGH NEAR ALASKA RETROGRADES, THE AREA OF BELOW NORMAL
TEMPERATURES ANTICIPATED OVER ALASKA EXPANDS DURING WEEK 2.

FOR PRECIPITATION, THE AREA OF ABOVE MEDIAN PRECIPITATION EXPECTED OVER THE
EAST-CENTRAL CONUS IS ALSO EXPECTED TO CONTRACT AS THE FRONTAL SYSTEM
ASSOCIATED WITH THE TROUGH FORECAST OVER THE EAST-CENTRAL CONUS SLIDES SLOWLY
SOUTHEASTWARD.

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 25% OF TODAY`S 0Z GFS ENSEMBLE
MEAN CENTERED ON DAY 11, 15% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY
11, 25% OF TODAY`S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 11, 5% OF TODAY`S
OPERATIONAL 6Z GFS CENTERED ON DAY 11, 20% OF TODAY`S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 10% OF YESTERDAY`S 12Z EUROPEAN ENSEMBLE MEAN CENTERED
ON DAY 10


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE
TO LARGE MODEL SPREAD AND UNCERTAINTY.

FORECASTER: RANDY SCHECHTER

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 17

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:
19970914 - 19950816 - 20040918 - 19600822 - 19520910


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:
19970914 - 19530825 - 19520909 - 20020904 - 19600823


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 10 - 14 2015

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     A    B
UTAH        A    B     ARIZONA     A    N     COLORADO    N    B
NEW MEXICO  A    N     N DAKOTA    B    B     S DAKOTA    B    B
NEBRASKA    B    B     KANSAS      B    N     OKLAHOMA    B    A
N TEXAS     N    A     S TEXAS     A    A     W TEXAS     N    A
MINNESOTA   B    N     IOWA        B    B     MISSOURI    B    A
ARKANSAS    B    A     LOUISIANA   N    A     WISCONSIN   B    N
ILLINOIS    B    A     MISSISSIPPI N    A     MICHIGAN    B    A
INDIANA     N    A     OHIO        A    A     KENTUCKY    N    A
TENNESSEE   A    A     ALABAMA     A    A     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  A    A
MARYLAND    A    A     DELAWARE    A    A     VIRGINIA    A    A
N CAROLINA  A    A     S CAROLINA  A    A     GEORGIA     A    A
FL PNHDL    A    A     FL PENIN    A    B     AK N SLOPE  B    B
AK ALEUTIAN B    B     AK WESTERN  B    B     AK INT BSN  B    N
AK S INT    B    A     AK SO COAST N    A     AK PNHDL    N    A



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 12 - 18 2015

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   B    B     WYOMING     N    B
UTAH        A    B     ARIZONA     A    N     COLORADO    N    B
NEW MEXICO  A    N     N DAKOTA    B    N     S DAKOTA    B    B
NEBRASKA    B    B     KANSAS      B    B     OKLAHOMA    B    N
N TEXAS     N    A     S TEXAS     A    A     W TEXAS     A    A
MINNESOTA   B    N     IOWA        B    B     MISSOURI    B    N
ARKANSAS    B    A     LOUISIANA   B    A     WISCONSIN   B    N
ILLINOIS    B    N     MISSISSIPPI B    A     MICHIGAN    B    N
INDIANA     B    N     OHIO        B    N     KENTUCKY    B    N
TENNESSEE   B    N     ALABAMA     B    A     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  N    N
MARYLAND    A    A     DELAWARE    A    A     VIRGINIA    A    A
N CAROLINA  A    A     S CAROLINA  A    A     GEORGIA     N    A
FL PNHDL    N    A     FL PENIN    A    N     AK N SLOPE  B    B
AK ALEUTIAN N    B     AK WESTERN  B    B     AK INT BSN  B    N
AK S INT    B    N     AK SO COAST B    N     AK PNHDL    N    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.

$$



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