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FXUS06 KWBC 181910
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT FRI AUGUST 18 2017

6-10 DAY OUTLOOK FOR AUG 24 - 28 2017

TODAY`S ENSEMBLE MEAN FORECASTS ARE IN FAIRLY GOOD AGREEMENT ON THE PREDICTED
MID-TROPOSPHERIC FLOW PATTERN FOR NORTH AMERICA. TROUGHS ARE ANTICIPATED OVER
THE NORTHEASTERN AND NORTHWESTERN LOWER 48 STATES AND WESTERN ALASKA, WHILE A
RIDGE IS EXPECTED OVER THE NORTH-CENTRAL CONUS. SEVERAL MODEL SOLUTIONS,
INCLUDING THE DETERMINISTIC 0Z ECMWF, AS WELL AS THE 0Z ECMWF AND CANADIAN
ENSEMBLE MEANS BRING A MEAN SURFACE LOW ASSOCIATED WITH TROPICAL STORM HARVEY
INTO THE BAY OF CAMPECHE/WESTERN GULF OF MEXICO DURING THIS TIME PERIOD. PLEASE
REFER TO THE NHC FOR THE LATEST UPDATES ON HARVEY. OTHERWISE, THE ENSEMBLE
SPAGHETTI CHARTS GENERALLY INDICATE MODERATE SPREAD OVER MUCH OF THE FORECAST
DOMAIN. TODAY`S 500-HPA BLEND CHART INDICATES NEAR TO BELOW NORMAL HEIGHTS OVER
THE NORTHEASTERN AND SOUTHERN CONUS, AS WELL AS MOST OF MAINLAND ALASKA, THE
NORTHERN ALASKA PANHANDLE, AND THE EASTERN ALEUTIANS. NEAR TO ABOVE NORMAL
HEIGHTS ARE EXPECTED ELSEWHERE OVER THE FORECAST DOMAIN.

A MEAN 500-HPA TROUGH AND SURFACE HIGH PRESSURE TILT THE ODDS TO BELOW NORMAL
TEMPERATURES FOR MUCH OF THE EASTERN AND CENTRAL CONUS. HOWEVER, ABOVE NORMAL
TEMPERATURES ARE FAVORED FOR THE FLORIDA PENINSULA AND PARTS OF THE GULF COAST
REGION TO THE SOUTH OF AN EXPECTED FRONTAL BOUNDARY. ABOVE NORMAL HEIGHTS FAVOR
ABOVE NORMAL TEMPERATURES FOR MUCH OF THE NORTHWESTERN CONUS, WHILE SUBTROPICAL
RIDGING LEADS TO ENHANCED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR MUCH
OF THE SOUTHWESTERN CONUS. THE TROUGH FORECAST OVER ALASKA TILTS THE ODDS TO
BELOW NORMAL TEMPERATURES NEAR THE ALASKA PENINSULA AND PARTS OF THE SOUTH
COAST, WHILE ABOVE NORMAL TEMPERATURE PROBABILITIES ARE ENHANCED FOR PARTS OF
NORTHEASTERN ALASKA WELL AHEAD OF THE TROUGH AXIS. BELOW NORMAL TEMPERATURE
PROBABILITIES ARE ENHANCED FOR PARTS OF THE ALASKA PANHANDLE CONSISTENT WITH
CALIBRATED TEMPERATURES FROM THE ECMWF ENSEMBLE MEMBERS.

SURFACE HIGH PRESSURE TILTS THE ODDS TO BELOW NORMAL PRECIPITATION FROM THE
UPPER MISSISSIPPI VALLEY TO THE GREAT LAKES AND MUCH OF THE NORTHEAST. A
FRONTAL SYSTEM AND MOIST FLOW AROUND THE PERIPHERY OF THE SURFACE HIGH OVER THE
EASTERN CONUS ENHANCE PROBABILITIES FOR ABOVE NORMAL PRECIPITATION FOR FLORIDA,
THE GULF COAST REGION, AND THE PLAINS. THE POTENTIAL FOR SHORTWAVE ENERGY
ASSOCIATED WITH A WEAK TROUGH OVER THE NORTHWEST U.S. SLIGHTLY ENHANCES
PROBABILITIES FOR ABOVE NORMAL PRECIPITATION FOR PARTS OF THE INTERIOR
NORTHWESTERN U.S. CALIBRATED PRECIPITATION ESTIMATES FROM THE ECMWF ENSEMBLE
MEMBERS FAVOR BELOW NORMAL PRECIPITATION FARTHER TO THE NORTH FOR PARTS OF THE
NORTHERN ROCKIES. SUBTROPICAL RIDGING LEADS TO ENHANCED PROBABILITIES FOR BELOW
NORMAL PRECIPITATION FOR PARTS OF ARIZONA. THE TROUGH EXPECTED OVER ALASKA
TILTS THE ODDS TO ABOVE NORMAL PRECIPITATION FOR SOUTHERN AND EASTERN MAINLAND
ALASKA AND THE ALASKA PANHANDLE WHILE BELOW NORMAL PRECIPITATION IS FAVORED FOR
PARTS OF NORTHWESTERN MAINLAND ALASKA BEHIND THE TROUGH AXIS.


TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 15% OF TODAY`S 0Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8, 15% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 5% OF
TODAY`S OPERATIONAL 0Z GFS CENTERED ON DAY 8, 10% OF TODAY`S OPERATIONAL 6Z 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, 10% 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
FAIRLY GOOD MODEL AGREEMENT, WITH SOME DISAGREEMENT AMONG THE FORECAST TOOLS

8-14 DAY OUTLOOK FOR AUG 26 - SEP 01, 2017

DURING THE WEEK-2 PERIOD, TROUGHING IS ANTICIPATED TO PERSIST NEAR THE ALASKA
PENINSULA WHILE HEIGHTS ARE EXPECTED TO RISE DOWNSTREAM OVER EASTERN MAINLAND
ALASKA, THE ALASKA PANHANDLE, AND MUCH OF THE NORTHWESTERN CONUS. A LESS
AMPLIFIED PATTERN IS EXPECTED FARTHER TO THE EAST AS THE RIDGE PREDICTED OVER
THE NORTHERN PLAINS DURING THE 6 TO 10 DAY PERIOD FLATTENS AND NEGATIVE HEIGHT
ANOMALIES ASSOCIATED WITH THE TROUGH OVER THE EASTERN CONUS WEAKEN.
CLIMATOLOGICAL SUBTROPICAL RIDGING IS EXPECTED OVER THE SOUTHWESTERN CONUS. THE
ENSEMBLE SPAGHETTI CHARTS INDICATE MODERATE SPREAD ACROSS MOST OF THE FORECAST
DOMAIN. TODAY`S 500-HPA BLEND CHART INDICATES NEAR TO ABOVE NORMAL HEIGHTS OVER
THE WESTERN CONUS, PARTS OF THE NORTHERN PLAINS AND MOST OF NORTHERN AND
EASTERN ALASKA, WHILE NEAR TO BELOW NORMAL HEIGHTS ARE ANTICIPATED OVER MOST OF
THE EASTERN CONUS AND OVER EXTREME SOUTHWESTERN MAINLAND ALASKA, THE ALASKA
PENINSULA, AND MOST OF THE ALEUTIANS.

THE TROUGH OVER THE EAST LEADS TO ENHANCED PROBABILITIES FOR NEAR TO BELOW
NORMAL TEMPERATURES FOR MOST OF THE EASTERN AND CENTRAL CONUS, WITH ENHANCED
ABOVE NORMAL TEMPERATURE PROBABILITIES RESTRICTED TO PARTS OF THE FLORIDA
PENINSULA AND SOUTHERN TEXAS. RIDGING AND ABOVE NORMAL HEIGHTS ELEVATE CHANCES
FOR ABOVE NORMAL TEMPERATURES FOR THE WESTERN THIRD OF THE CONUS. ABOVE NORMAL
TEMPERATURES ARE ALSO FAVORED FOR NORTHEASTERN MAINLAND ALASKA WELL AHEAD OF
THE TROUGH EXPECTED NEAR THE ALASKA PENINSULA.

RISING HEIGHTS OVER THE NORTHWESTERN CONUS LEADS TO ENHANCED PROBABILITIES FOR
BELOW NORMAL PRECIPITATION FOR THE REGION. RETURN FLOW AROUND A MEAN SURFACE
HIGH OVER THE EASTERN CONUS, AIDED BY POTENTIAL INFLUXES OF MOISTURE FROM THE
GULF OF MEXICO TILT THE ODDS TO ABOVE NORMAL PRECIPITATION FOR MUCH OF THE
CENTRAL AND SOUTHERN PLAINS. ABOVE NORMAL PRECIPITATION IS ALSO LIKELY FOR
FLORIDA NEAR A POTENTIAL FRONTAL BOUNDARY. MOIST FLOW AHEAD OF A TROUGH NEAR
THE ALASKA PENINSULA LEADS TO ENHANCED PROBABILITIES FOR ABOVE NORMAL
PRECIPITATION FOR SOUTHEASTERN MAINLAND ALASKA AND THE ALASKA PANHANDLE. BELOW
NORMAL PRECIPITATION IS FAVORED FOR NORTHWESTERN ALASKA UNDERNEATH ANOMALOUS
EASTERLY FLOW.

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


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOUT AVERAGE, 3 OUT OF 5, DUE
TO FAIRLY GOOD MODEL AGREEMENT OFFSET BY SOME DISAGREEMENT AMONG THE TOOLS

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:
19690816 - 19910802 - 19800814 - 19660813 - 19580805


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:
19910731 - 19690815 - 19660811 - 19660816 - 19530813


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

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



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 26 - SEP 01, 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       A    B     NEVADA      A    N
W MONTANA   A    B     E MONTANA   A    B     WYOMING     A    N
UTAH        A    N     ARIZONA     A    N     COLORADO    A    A
NEW MEXICO  A    A     N DAKOTA    N    N     S DAKOTA    N    N
NEBRASKA    B    A     KANSAS      B    A     OKLAHOMA    B    A
N TEXAS     B    A     S TEXAS     N    A     W TEXAS     B    A
MINNESOTA   N    N     IOWA        B    N     MISSOURI    B    N
ARKANSAS    B    A     LOUISIANA   B    A     WISCONSIN   N    B
ILLINOIS    B    B     MISSISSIPPI B    N     MICHIGAN    N    B
INDIANA     B    B     OHIO        B    B     KENTUCKY    B    B
TENNESSEE   B    B     ALABAMA     B    N     NEW YORK    B    B
VERMONT     B    B     NEW HAMP    B    B     MAINE       N    B
MASS        B    B     CONN        B    B     RHODE IS    B    N
PENN        B    B     NEW JERSEY  B    B     W VIRGINIA  B    B
MARYLAND    B    B     DELAWARE    B    B     VIRGINIA    B    B
N CAROLINA  B    B     S CAROLINA  B    B     GEORGIA     B    N
FL PNHDL    N    A     FL PENIN    A    A     AK N SLOPE  A    B
AK ALEUTIAN N    B     AK WESTERN  N    B     AK INT BSN  A    N
AK S INT    N    A     AK SO COAST N    A     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.

$$



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