Prognostic Meteorological Discussion
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FXUS06 KWBC 211919
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT MON AUGUST 21 2017

6-10 DAY OUTLOOK FOR AUG 27 - 31 2017

TODAY`S MODEL SOLUTIONS ARE IN FAIRLY GOOD AGREEMENT ON THE PREDICTED
MID-TROPOSPHERIC FLOW PATTERN FOR NORTH AMERICA. AN AMPLIFIED PATTERN FOR THIS
TIME OF YEAR IS PREDICTED WITH TROUGHS ANTICIPATED OVER SOUTHWESTERN ALASKA AND
OVER THE EASTERN CONUS EXTENDING TO THE SOUTHERN PLAINS. RIDGING IS EXPECTED
OVER MUCH OF THE WESTERN CONUS. ENSEMBLE SPREAD IS MODERATE OVER MUCH OF THE
FORECAST DOMAIN WITH MOST MEMBERS INDICATING BELOW NORMAL HEIGHTS FOR MUCH OF
ALASKA AND THE EASTERN CONUS AND ABOVE NORMAL HEIGHTS FOR THE WESTERN CONUS.

RIDGING AND ABOVE NORMAL HEIGHTS FAVOR ABOVE NORMAL TEMPERATURES FOR THE
WESTERN CONUS. A FRONTAL BOUNDARY ASSOCIATED WITH THE TROUGH OVER THE EASTERN
CONUS IS EXPECTED TO PROGRESS FAR TO THE SOUTH FOR THIS TIME OF THE YEAR,
LEADING TO ENHANCED PROBABILITIES FOR BELOW NORMAL TEMPERATURES FOR MUCH OF THE
EASTERN CONUS. FAVORED ABOVE NORMAL TEMPERATURES ARE RESTRICTED TO THE SOUTHERN
FLORIDA PENINSULA TO THE SOUTH OF THE EXPECTED FRONTAL BOUNDARY. 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 THE ALASKA PANHANDLE WELL AHEAD OF THE
TROUGH AXIS.

ABOVE NORMAL PRECIPITATION IS FAVORED FOR THE SOUTHERN PLAINS, THE GULF COAST
REGION, AND THE FLORIDA PENINSULA DUE TO A NEARBY FRONTAL BOUNDARY AND
POTENTIAL INFLUXES OF TROPICAL MOISTURE. SURFACE HIGH PRESSURE TILTS THE ODDS
TO BELOW NORMAL PRECIPITATION FOR MUCH OF THE EASTERN SEABOARD. MOIST SOUTHERLY
FLOW AROUND THE PERIPHERY OF THE SURFACE HIGH ENHANCES PROBABILITIES FOR ABOVE
NORMAL PRECIPITATION FOR PARTS OF THE GREAT LAKES REGION. RIDGING LEADS TO
ENHANCED PROBABILITIES FOR NEAR TO BELOW NORMAL PRECIPITATION FOR MUCH OF THE
WESTERN CONUS AND NORTHERN PLAINS. 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, 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, 20% 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: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
FAIRLY GOOD MODEL AGREEMENT ON AN AMPLIFIED FLOW PATTERN OVER MUCH OF THE
FORECAST DOMAIN.

8-14 DAY OUTLOOK FOR AUG 29 - SEP 04, 2017

DURING THE WEEK-2 PERIOD, A TROUGH IS ANTICIPATED TO RETROGRADE SLIGHTLY TO THE
SOUTH OF THE ALEUTIANS AND HEIGHTS ARE EXPECTED TO RISE DOWNSTREAM OVER EASTERN
MAINLAND ALASKA AND MUCH OF THE ALASKA PANHANDLE. THE RIDGE OVER THE WESTERN
CONUS IS PREDICTED TO FLATTEN RELATIVE TO THE 6 TO 10 DAY PERIOD BUT HEIGHTS
ARE EXPECTED TO REMAIN ABOVE NORMAL. A TROUGH IS ANTICIPATED OVER THE EASTERN
CONUS CENTERED FROM THE GREAT LAKES TO THE LOWER MISSISSIPPI VALLEY. THE
ENSEMBLE SPAGHETTI CHARTS INDICATE MODERATE TO HIGH SPREAD ACROSS MUCH OF THE
FORECAST DOMAIN. TODAY`S 500-HPA BLEND CHART INDICATES NEAR TO ABOVE NORMAL
HEIGHTS OVER THE WESTERN CONUS AND EASTERN ALASKA, WHILE NEAR TO BELOW NORMAL
HEIGHTS ARE ANTICIPATED OVER MOST OF THE EASTERN CONUS AND SOUTHWESTERN ALASKA.

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 EASTERN NEW ENGLAND. 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 PARTS OF EASTERN AND CENTRAL MAINLAND
ALASKA AND THE ALASKA PANHANDLE WELL AHEAD OF THE TROUGH EXPECTED SOUTH OF THE
ALEUTIANS.

RIDGING LEADS TO ENHANCED PROBABILITIES FOR BELOW NORMAL PRECIPITATION FOR MUCH
OF THE NORTHWESTERN AND NORTH-CENTRAL CONUS. A MEAN TROUGH TILTS THE ODDS TO
ABOVE NORMAL PRECIPITATION FOR MUCH OF THE SOUTH-CENTRAL AND SOUTHEASTERN CONUS
AS WELL AS PARTS OF THE GREAT LAKES REGION. PROBABILITIES FOR ABOVE NORMAL
PRECIPITATION ARE ENHANCED FOR PARTS OF THE SOUTHWESTERN CONUS DUE TO POTENTIAL
ADVECTION OF TROPICAL MOISTURE INTO THE REGION. MOIST FLOW AHEAD OF A TROUGH
SOUTH OF THE ALEUTIANS 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: 30% OF TODAY`S 0Z GFS ENSEMBLE
MEAN CENTERED ON DAY 11, 35% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY
11, 5% OF TODAY`S OPERATIONAL 0Z GFS CENTERED ON DAY 11, 15% 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: ABOUT AVERAGE, 3 OUT OF 5, DUE
TO FAIRLY GOOD AGREEMENT AMONG THE ENSEMBLE MEANS OFFSET BY MODERATE TO HIGH
SPREAD AMONG THE COMPONENT ENSEMBLE MEMBERS.

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:
19910801 - 19660815 - 19580904 - 19530811 - 19980826


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:
19660814 - 19580903 - 19910731 - 19530812 - 19800903


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 27 - 31 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    B
UTAH        A    B     ARIZONA     A    N     COLORADO    A    B
NEW MEXICO  A    N     N DAKOTA    N    B     S DAKOTA    N    B
NEBRASKA    B    B     KANSAS      B    N     OKLAHOMA    B    A
N TEXAS     B    A     S TEXAS     B    A     W TEXAS     B    A
MINNESOTA   N    N     IOWA        B    N     MISSOURI    B    N
ARKANSAS    B    A     LOUISIANA   B    A     WISCONSIN   N    N
ILLINOIS    B    N     MISSISSIPPI B    A     MICHIGAN    N    N
INDIANA     B    N     OHIO        B    N     KENTUCKY    B    N
TENNESSEE   B    N     ALABAMA     B    A     NEW YORK    B    B
VERMONT     B    B     NEW HAMP    B    B     MAINE       N    B
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    B     S CAROLINA  B    B     GEORGIA     B    B
FL PNHDL    B    A     FL PENIN    N    A     AK N SLOPE  N    B
AK ALEUTIAN N    N     AK WESTERN  N    B     AK INT BSN  N    N
AK S INT    B    A     AK SO COAST B    A     AK PNHDL    A    A



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 29 - SEP 04, 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    N    N
NEW MEXICO  N    N     N DAKOTA    N    B     S DAKOTA    N    B
NEBRASKA    B    B     KANSAS      B    N     OKLAHOMA    B    N
N TEXAS     B    A     S TEXAS     B    A     W TEXAS     B    N
MINNESOTA   N    B     IOWA        B    B     MISSOURI    B    N
ARKANSAS    B    N     LOUISIANA   B    A     WISCONSIN   N    B
ILLINOIS    B    N     MISSISSIPPI B    A     MICHIGAN    N    A
INDIANA     B    N     OHIO        B    A     KENTUCKY    B    N
TENNESSEE   B    A     ALABAMA     B    A     NEW YORK    N    A
VERMONT     N    N     NEW HAMP    N    N     MAINE       A    N
MASS        N    N     CONN        N    N     RHODE IS    N    N
PENN        B    A     NEW JERSEY  N    N     W VIRGINIA  B    N
MARYLAND    B    N     DELAWARE    B    N     VIRGINIA    B    N
N CAROLINA  B    N     S CAROLINA  B    N     GEORGIA     B    A
FL PNHDL    B    A     FL PENIN    A    A     AK N SLOPE  N    N
AK ALEUTIAN N    N     AK WESTERN  N    B     AK INT BSN  A    N
AK S INT    A    A     AK SO COAST N    A     AK PNHDL    A    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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