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FXUS06 KWBC 171902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT THU AUGUST 17 2017

6-10 DAY OUTLOOK FOR AUG 23 - 27 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 ALASKA, WHILE A RIDGE IS
EXPECTED OVER THE WEST-CENTRAL CONUS. THE DETERMINISTIC SOLUTIONS FROM THE GFS
AND ECMWF ARE IN BASICALLY GOOD AGREEMENT WITH THE ENSEMBLE MEAN FORECASTS,
EXCEPT AS IS TYPICALLY THE CASE, THEY ARE MORE AMPLIFIED WITH THE MAIN
CIRCULATION FEATURES. THE ENSEMBLE SPAGHETTI CHARTS GENERALLY INDICATE LOW
SPREAD OVER THE EASTERN CONUS, AND MODERATE SPREAD OVER THE WESTERN CONUS AND
EASTERN PACIFIC. TODAY`S 500-HPA BLEND CHART INDICATES NEAR TO ABOVE NORMAL
HEIGHTS OVER THE NORTHWESTERN AND NORTH-CENTRAL CONUS, AND CENTRAL AND NORTHERN
MAINLAND ALASKA, WHILE NEAR TO BELOW NORMAL HEIGHTS ARE ANTICIPATED OVER THE
REMAINDER OF THE FORECAST DOMAIN.

BELOW NORMAL HEIGHTS TILT THE ODDS TO BELOW NORMAL TEMPERATURES FOR MUCH OF THE
NORTHEASTERN U.S., WHILE ABOVE NORMAL HEIGHTS FAVOR ABOVE NORMAL TEMPERATURES
FOR MUCH OF THE NORTHWESTERN CONUS. THE EXPECTATION OF NEAR NORMAL HEIGHTS AND
ABOVE NORMAL TEMPERATURES EARLY IN THE PERIOD ENHANCES PROBABILITIES FOR ABOVE
NORMAL TEMPERATURES FOR MUCH OF THE SOUTHERN TIER OF THE CONUS. THE TROUGH
FORECAST OVER ALASKA TILTS THE ODDS TO BELOW NORMAL TEMPERATURES FOR THE
WESTERN PART OF THE STATE, WHILE ABOVE NORMAL SEA SURFACE TEMPERATURES ENHANCE
PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR THE WESTERN ALEUTIANS.

ANOMALOUS NORTHWESTERLY FLOW TILTS THE ODDS TO BELOW NORMAL PRECIPITATION NEAR
THE GREAT LAKES AND PARTS OF THE OHIO VALLEY. A FRONTAL SYSTEM AND THE
POSSIBILITY OF TROPICAL MOISTURE ENHANCE PROBABILITIES FOR ABOVE NORMAL
PRECIPITATION FOR FLORIDA AND PARTS OF THE SOUTHEAST. THE TROUGH FORECAST OVER
THE NORTHEAST FAVORS ABOVE NORMAL PRECIPITATION FOR MAINE. MONSOONAL MOISTURE
AND THE LIKELIHOOD OF MCS ACTIVITY TILT THE ODDS TO ABOVE NORMAL PRECIPITATION
FOR PARTS OF THE WEST-CENTRAL CONUS. A TROUGH EXPECTED OVER THE NORTHWEST U.S.
ENHANCES PROBABILITIES FOR ABOVE NORMAL PRECIPITATION FOR PARTS OF THE INTERIOR
NORTHWESTERN U.S. ANOMALOUS NORTHEASTERLY FLOW FAVORS BELOW NORMAL
PRECIPITATION FOR PARTS OF NORTHWESTERN MAINLAND ALASKA, WHILE THE TROUGH
EXPECTED OVER ALASKA TILT THE ODDS TO ABOVE NORMAL PRECIPITATION FOR
SOUTHEASTERN MAINLAND ALASKA AND THE ALASKA PANHANDLE.


TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 20% OF TODAY`S 0Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8, 10% OF TODAY`S 6Z GFS ENSEMBLE MEAN 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, 10% OF YESTERDAY`S 12Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 7, 10% OF TODAY`S OPERATIONAL 0Z ECMWF CENTERED ON DAY 8, AND
10% 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 25 - 31 2017

DURING THE WEEK-2 PERIOD, A LESS AMPLIFIED PATTERN IS EXPECTED. THE TROUGH OVER
THE NORTHEASTERN CONUS IS FORECAST TO PROGRESS NORTHEASTWARD AND WEAKEN AS THE
NORTHERN PART OF THE RIDGE OVER THE WEST-CENTRAL U.S. GETS FLATTENED BY TROUGH
ENERGY PROGRESSING EASTWARD FROM THE NORTHWESTERN CONUS. TROUGHING IS
ANTICIPATED TO PERSIST OVER MUCH OF WESTERN AND CENTRAL MAINLAND ALASKA. THE
ENSEMBLE SPAGHETTI CHARTS INDICATE MODERATE TO LARGE SPREAD ACROSS MOST OF THE
FORECAST DOMAIN. TODAY`S 500-HPA BLEND CHART INDICATES NEAR TO ABOVE NORMAL
HEIGHTS OVER THE NORTHWESTERN HALF OF THE CONUS AND MOST OF ALASKA, WHILE NEAR
TO BELOW NORMAL HEIGHTS ARE ANTICIPATED OVER THE SOUTHEASTERN HALF OF THE CONUS
AND OVER EXTREME SOUTHWESTERN MAINLAND ALASKA AND THE ALASKA PENINSULA.

THE TEMPERATURE PROBABILITY FORECAST DURING THE WEEK-2 PERIOD IS SIMILAR TO THE
6-10 DAY PERIOD, WITH A COUPLE OF EXCEPTIONS. AS SURFACE HIGH PRESSURE BUILDS
SOUTHEASTWARD DURING WEEK 2, A SOMEWHAT COOLER PATTERN IS EXPECTED ALONG MUCH
OF THE GULF COAST, WHILE AS MID-LEVEL HEIGHTS RISE OVER THE SOUTHWEST U.S. A
WARMER REGIME IS ANTICIPATED FOR SOUTHERN CALIFORNIA AND PARTS OF NORTHERN
ARIZONA.

RISING HEIGHTS OVER THE NORTHWESTERN CONUS LEADS TO ENHANCED PROBABILITIES FOR
BELOW NORMAL PRECIPITATION FOR THE REGION. RESIDUAL MONSOONAL MOISTURE, IN
COMBINATION WITH POSSIBLE MCS ACTIVITY TILT THE ODDS TO ABOVE NORMAL
PRECIPITATION FOR PARTS OF THE CENTRAL AND SOUTHERN PLAINS. ABOVE NORMAL
PRECIPITATION IS ALSO ANTICIPATED FOR FLORIDA AS A FRONT DISSIPATES OVER THE
REGION AND TROPICAL WAVES APPROACH FROM THE TROPICAL ATLANTIC. ABOVE NORMAL
HEIGHTS TILT THE ODDS TO BELOW NORMAL PRECIPITATION FOR NORTHERN MAINLAND
ALASKA, WHILE ANOMALOUS SOUTHWESTERLY FLOW LEADS TO ENHANCED PROBABILITIES FOR
ABOVE NORMAL PRECIPITATION FOR THE SOUTHEASTERN MAINLAND ALASKA AND THE ALASKA
PANHANDLE.

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 25% OF TODAY`S 0Z GFS ENSEMBLE
MEAN CENTERED ON DAY 11, 5% 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 0Z GFS CENTERED ON DAY 11, 25% 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: ABOUT AVERAGE, 3 OUT OF 5, DUE
TO FAIRLY GOOD MODEL AGREEMENT, WITH SOME DISAGREEMENT AMONG THE TEMPERATURE
TOOLS

FORECASTER: RANDY S

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:
19800814 - 19690817 - 19910802 - 19640818 - 19660812


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:
19660810 - 19800813 - 19640817 - 19690816 - 19660816


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 23 - 27 2017

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



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 25 - 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    N     WYOMING     A    N
UTAH        A    N     ARIZONA     A    N     COLORADO    N    A
NEW MEXICO  A    A     N DAKOTA    N    N     S DAKOTA    N    N
NEBRASKA    N    N     KANSAS      B    A     OKLAHOMA    B    A
N TEXAS     N    A     S TEXAS     A    A     W TEXAS     N    A
MINNESOTA   N    N     IOWA        B    N     MISSOURI    B    N
ARKANSAS    B    N     LOUISIANA   N    A     WISCONSIN   B    B
ILLINOIS    B    N     MISSISSIPPI N    N     MICHIGAN    B    B
INDIANA     B    B     OHIO        B    B     KENTUCKY    B    N
TENNESSEE   B    N     ALABAMA     B    N     NEW YORK    B    B
VERMONT     B    B     NEW HAMP    B    B     MAINE       B    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    N     S CAROLINA  B    N     GEORGIA     N    N
FL PNHDL    N    A     FL PENIN    A    A     AK N SLOPE  N    B
AK ALEUTIAN N    N     AK WESTERN  B    B     AK INT BSN  N    N
AK S INT    B    N     AK SO COAST B    A     AK PNHDL    B    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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