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FXUS06 KWBC 221937
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 22 2017

6-10 DAY OUTLOOK FOR SEP 28 - OCT 02, 2017

TODAY`S ENSEMBLE MEAN SOLUTIONS ARE IN RELATIVELY GOOD AGREEMENT ON A FAIRLY
AMPLIFIED FLOW PATTERN OVER MUCH OF THE FORECAST DOMAIN. HOWEVER, SPREAD AND
UNCERTAINTY ARE HIGH AMONG THE COMPONENT ENSEMBLE MEMBERS OVER MUCH OF THE
COUNTRY, ESPECIALLY IN THE WESTERN CONUS. A TROUGH IS FORECAST OVER MUCH OF
ALASKA AND A RIDGE IS EXPECTED TO BUILD DOWNSTREAM OVER THE NORTHWESTERN CONUS.
TROUGHS ARE PREDICTED OVER THE SOUTHWESTERN CONUS AND IN THE EASTERN U.S. THERE
ARE SOME MODEL DIFFERENCES REGARDING THE POSITION OF THE EASTERN TROUGH. FOR
EXAMPLE, TODAY`S GFS, CANADIAN, AND ECMWF ENSEMBLE MEANS FORECAST THE TROUGH
OVER THE NORTHEAST, BUT THE DETERMINISTIC GFS HAS CONSISTENTLY FORECAST THE
TROUGH TO BE CENTERED CLOSER TO THE OHIO VALLEY. SINCE TODAY`S MANUAL 500-HPA
BLEND FAVORS TODAY`S 0Z ECMWF ENSEMBLE MEAN, THE TROUGH IS EXPECTED TO BE OVER
THE NORTHEAST DURING THE 6-10 DAY PERIOD.

TROUGH ENERGY FORECAST TO MOVE THROUGH PARTS OF THE SOUTHWEST AND SOUTHERN
PLAINS INCREASES CHANCES FOR BELOW NORMAL TEMPERATURES FOR MUCH OF THE
SOUTH-CENTRAL CONUS AND INTO THE GREAT LAKES REGION. ABOVE NORMAL TEMPERATURES
ARE STRONGLY FAVORED ALONG THE WEST COAST DUE TO A RIDGE AND ABOVE NORMAL SSTS.
ENHANCED PROBABILITIES OF ABOVE NORMAL TEMPERATURES ARE INDICATED FOR COAST
PARTS OF THE SOUTHEAST AND FLORIDA DUE TO THOSE AREAS BEING AHEAD OF A FORECAST
TROUGH. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR PARTS OF EASTERN MAINLAND
ALASKA, AND THE PANHANDLE, CONSISTENT WITH THE REFORECAST-CALIBRATED
CONSOLIDATED FORECAST GUIDANCE. ENHANCED PROBABILITIES FOR BELOW NORMAL
TEMPERATURES ARE INDICATED FOR PARTS OF THE ALEUTIANS DUE TO ANOMALOUS
NORTHERLY FLOW.

THERE ARE LARGELY ENHANCED PROBABILITIES FOR ABOVE NORMAL PRECIPITATION OVER
MUCH OF THE SOUTH-CENTRAL CONUS AND PARTS OF THE SOUTHWEST IN ASSOCIATION WITH
A TROUGH OVER THE SOUTHWESTERN CONUS DURING THE EARLY PART OF THE PERIOD, AND
THE POTENTIAL ADVECTION OF TROPICAL MOISTURE INTO THE REGION. BELOW NORMAL
PRECIPITATION IS FAVORED FOR THE NORTHWESTERN CONUS DUE TO EXPECTED RIDGING.
THERE ARE INCREASED ODDS FOR ABOVE NORMAL PRECIPITATION FOR PARTS OF THE EAST
COAST DUE TO A STORM SYSTEM PREDICTED TO DEVELOP NEAR THE END OF THE PERIOD.
SINCE YESTERDAY, MODEL GUIDANCE AND THE OFFICIAL NHC FORECAST FAVOR HURRICANE
MARIA RECURVING AND NOT IMPACTING THE U.S. NEVERTHELESS UNCERTAINTY IS HIGH
WITH ANY TROPICAL SYSTEM, AND INTERESTS ALONG THE EAST COAST ARE STRONGLY
ENCOURAGED TO CLOSELY MONITOR THE LATEST UPDATES FROM THE NHC. RELATIVELY HIGH
SURFACE PRESSURE AND LOW-LEVEL FLOW FORECAST TO ORIGINATE OVER LAND LEADS TO
INCREASED ODDS FOR NEAR TO BELOW NORMAL PRECIPITATION FOR ALASKA. BELOW NORMAL
PRECIPITATION IS FAVORED WEST OF THE TROUGH FOR PARTS OF WESTERN MAINLAND
ALASKA AND THE ALEUTIANS. BELOW NORMAL PRECIPITATION IS FAVORED FOR MUCH OF THE
NORTHERN CONUS, GREAT LAKES REGION AND OHIO AND TENNESSEE VALLEYS BEHIND THE
TROUGH FORECAST IN THE EASTERN U.S.

TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 40% OF TODAY`S OPERATIONAL 6Z GFS
CENTERED ON DAY 8, AND 60% OF TODAY`S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY
8


FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
FAIRLY GOOD AGREEMENT AMONG THE MODELS AND TOOLS OVER MOST OF THE U.S.

8-14 DAY OUTLOOK FOR SEP 30 - OCT 06, 2017

DURING THE WEEK-2 PERIOD, THE OVERALL 500-HPA FLOW PATTERN IS EXPECTED TO BE
VERY SIMILAR, EXCEPT SOMEWHAT LESS AMPLIFIED AND SHIFTED EASTWARD.

THE TEMPERATURE PROBABILITIES FORECAST DURING THE 6-10 DAY PERIOD ARE SIMILAR
TO THOSE FORECAST DURING THE WEEK-2 PERIOD, WITH A FEW EXCEPTIONS. LESS
NORTHERLY LOW-LEVEL FLOW IS FORECAST OVER ALASKA DURING THE WEEK-2 PERIOD,
FAVORING ABOVE NORMAL TEMPERATURES FOR MOST OF THE STATE. THE TEMPERATURE
PATTERN ACROSS THE REST OF THE U.S. IS FORECAST TO SHIFT EAST, CORRESPONDING TO
THE EASTWARD SHIFT OF THE 500-HPA PATTERN.

THE PRECIPITATION PROBABILITIES FORECAST DURING THE 6-10 DAY PERIOD ARE SIMILAR
TO THE WEEK-2 PERIOD, WITH SOME EXCEPTIONS. TODAY`S MODELS ARE HINTING AT MORE
TROUGH ENERGY POSSIBLY ENTERING THE PACIFIC NORTHWEST DURING THE WEEK-2 PERIOD,
FAVORING NEAR NORMAL PRECIPITATION THERE, INSTEAD OF BELOW NORMAL PRECIPITATION
LIKE THE 6-10 DAY PERIOD. THE STORM SYSTEM FORECAST TO BRING A LOT OF
PRECIPITATION TO PARTS OF THE SOUTH DURING THE 6-10 DAY PERIOD IS EXPECTED TO
EXIT THE COUNTRY NEAR THE BEGINNING OF THE WEEK-2 PERIOD, SO ABOVE NORMAL
PRECIPITATION IS ONLY FAVORED NEAR THE MEXICAN BORDER IN TEXAS AND PARTS OF NEW
MEXICO. THE STORM SYSTEM PREDICTED TO AFFECT THE EASTERN U.S. DURING THE 6-10
DAY PERIOD IS FORECAST TO EXIT BEFORE THE WEEK-2 PERIOD, FAVORING NEAR NORMAL
PRECIPITATION FOR COASTAL PARTS OF THE NORTHEAST. CHANCES FOR ABOVE NORMAL
PRECIPITATION ARE ELEVATED FOR PARTS OF FLORIDA AND THE MID-ATLANTIC REGION
WHERE SEVERAL STORM SYSTEMS ARE EXPECTED TO DEVELOP DURING THE PERIOD.

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 25% OF TODAY`S 6Z GFS ENSEMBLE
MEAN CENTERED ON DAY 11, 40% OF YESTERDAY`S OPERATIONAL 18Z GFS CENTERED ON DAY
10, AND 35% OF TODAY`S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: BELOW AVERAGE, 2 OUT OF 5, DUE
TO FAIRLY LARGE UNCERTAINTY IN TODAY`S ENSEMBLES

FORECASTER: MIKE C

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
OCTOBER 19

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:
19710929 - 19860924 - 20040918 - 19831001 - 20020902


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:
19860927 - 19830930 - 19710928 - 19860922 - 19820929


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 28 - OCT 02, 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    B
W MONTANA   A    B     E MONTANA   A    B     WYOMING     A    B
UTAH        N    N     ARIZONA     A    N     COLORADO    B    A
NEW MEXICO  B    A     N DAKOTA    A    B     S DAKOTA    A    B
NEBRASKA    N    B     KANSAS      B    B     OKLAHOMA    B    N
N TEXAS     B    A     S TEXAS     B    A     W TEXAS     B    A
MINNESOTA   N    B     IOWA        B    B     MISSOURI    B    B
ARKANSAS    B    B     LOUISIANA   N    N     WISCONSIN   B    B
ILLINOIS    B    B     MISSISSIPPI N    B     MICHIGAN    N    B
INDIANA     B    B     OHIO        N    B     KENTUCKY    N    B
TENNESSEE   N    B     ALABAMA     A    B     NEW YORK    N    N
VERMONT     N    N     NEW HAMP    N    A     MAINE       N    A
MASS        N    A     CONN        N    A     RHODE IS    N    A
PENN        N    N     NEW JERSEY  N    A     W VIRGINIA  N    N
MARYLAND    N    N     DELAWARE    N    A     VIRGINIA    N    N
N CAROLINA  A    A     S CAROLINA  A    N     GEORGIA     A    N
FL PNHDL    A    N     FL PENIN    A    N     AK N SLOPE  N    N
AK ALEUTIAN B    B     AK WESTERN  N    B     AK INT BSN  A    N
AK S INT    A    B     AK SO COAST A    B     AK PNHDL    A    A



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR SEP 30 - OCT 06, 2017

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

                           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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