Prognostic Meteorological Discussion
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FXUS06 KWBC 191916
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT THU OCTOBER 19 2017

6-10 DAY OUTLOOK FOR OCT 25 - 29 2017

TODAY`S ENSEMBLE MEAN SOLUTIONS ARE GENERALLY IN GOOD AGREEMENT ON AN AMPLIFIED
FLOW PATTERN OVER MOST OF THE FORECAST DOMAIN. A 500-HPA TROUGH IS FORECAST
OVER WESTERN ALASKA. DOWNSTREAM A STRONG RIDGE IS PREDICTED OVER THE WESTERN
HALF OF THE CONUS. A TROUGH IS FORECAST OVER THE EASTERN CONUS. TODAY`S 500-HPA
MANUAL BLEND FEATURES NEGATIVE HEIGHT ANOMALIES OVER MOST OF ALASKA (WITH THE
EXCEPTION OF THE PANHANDLE), POSITIVE HEIGHT ANOMALIES OVER THE WESTERN HALF OF
THE CONUS AS WELL AS PARTS OF THE NORTHEASTERN CONUS, AND NEGATIVE HEIGHT
ANOMALIES OVER THE REMAINDER OF THE CONUS.

A STRONG RIDGE PREDICTED OVER THE WESTERN CONUS HIGHLY FAVORS ABOVE NORMAL
TEMPERATURES FOR THE WESTERN HALF OF THE CONUS, ESPECIALLY FOR SOUTHERN
CALIFORNIA AND PARTS OF THE SOUTHWEST. THIS RIDGE IS FORECAST TO EXTEND INTO
PARTS OF EASTERN ALASKA, FAVORING ABOVE NORMAL TEMPERATURES FOR PARTS OF
EASTERN ALASKA AND THE ALASKA PANHANDLE. A FORECAST TROUGH AND COLD AIR
ADVECTION BEHIND FRONTAL PASSAGES INCREASE THE LIKELIHOOD OF BELOW NORMAL
TEMPERATURES FOR MUCH OF THE EASTERN U.S. HOWEVER, IN PARTS OF THE NORTHEAST,
POSITIVE HEIGHT ANOMALIES AHEAD OF THE TROUGH AXIS FAVOR ABOVE NORMAL
TEMPERATURES THERE.

STORM SYSTEM ACTIVITY IS FORECAST TO TRAVEL AROUND THE CLOSED LOW, CENTERED
OVER PARTS OF ALASKA, INCREASING THE LIKELIHOOD FOR ABOVE NORMAL PRECIPITATION
FOR MUCH OF ALASKA AND EXTREME NORTHERN PORTIONS OF THE PACIFIC NORTHWEST. THE
WESTERN RIDGE IS FORECAST TO PREVENT STORM SYSTEMS FROM COMING INTO THE WESTERN
CONUS, STRONGLY FAVORING BELOW NORMAL PRECIPITATION OVER MUCH OF THE CONUS.
HOWEVER, ABOVE NORMAL PRECIPITATION IS FAVORED FOR PARTS OF THE NORTHEAST AHEAD
OF THE TROUGH OVER THE EASTERN CONUS.

TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 20% OF TODAY`S OPERATIONAL 6Z GFS
CENTERED ON DAY 8, AND 80% 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
GOOD AGREEMENT AMONG THE MODELS ON AN AMPLIFIED FLOW PATTERN.

8-14 DAY OUTLOOK FOR OCT 27 - NOV 02, 2017

DURING THE WEEK-2 PERIOD, MODEL AGREEMENT IS RELATIVELY POOR AND THERE IS LARGE
SPREAD AMONG THE ENSEMBLE MEMBERS OVER MUCH OF THE OF THE FORECAST DOMAIN. AT
THE BEGINNING OF THE PERIOD, A TROUGH IS EXPECTED OVER THE EASTERN U.S. WHILE
RIDGING IS FORECAST OVER THE WESTERN CONUS. THEREAFTER, THE ENSEMBLE MEAN
SOLUTIONS DE-AMPLIFY THE OVERALL PATTERN DUE, IN PART, TO INCREASED UNCERTAINTY
AND SPREAD AMONG THE COMPONENT ENSEMBLE MEMBERS. THE ENSEMBLE MEAN SOLUTIONS
GENERALLY AGREE IN FORECASTING A MEAN TROUGH AND ASSOCIATED BELOW NORMAL
HEIGHTS OVER MUCH OF ALASKA. HOWEVER, MODEL SPREAD IS HIGH AND CONSISTENCY
AMONG THE DETERMINISTIC GFS RUNS IS POOR FOR THE REGION. DUE TO LARGE MODEL
UNCERTAINTIES, TODAY`S WEEK-2 500-HPA BLEND RELIES HEAVILY ON THE ENSEMBLE MEAN
SOLUTIONS.

BELOW NORMAL TEMPERATURES ARE FAVORED FOR THE SOUTHEASTERN CONUS DUE TO A
TROUGH EXPECTED OVER THE EASTERN CONUS (PARTICULARLY EARLY IN THE PERIOD).
ABOVE NORMAL TEMPERATURE PROBABILITIES ARE ENHANCED FOR PARTS OF THE
NORTHEASTERN CONUS AHEAD OF THE EXPECTED TROUGH AXIS. ABOVE NORMAL HEIGHTS LEAD
TO ENHANCED PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR MOST OF THE WESTERN
AND NORTH-CENTRAL CONUS.  THERE ARE INCREASED ODDS OF ABOVE NORMAL TEMPERATURES
FOR PARTS OF EASTERN MAINLAND ALASKA AND THE ALASKA PANHANDLE AHEAD OF A
TROUGH. BELOW NORMAL TEMPERATURES ARE FAVORED BEHIND THE TROUGH AXIS FOR PARTS
OF SOUTHWESTERN ALASKA.

MEAN SURFACE HIGH PRESSURE LEADS TO ENHANCED PROBABILITIES FOR BELOW NORMAL
PRECIPITATION OVER MUCH OF THE CONUS. HOWEVER, NEAR TO ABOVE NORMAL
PRECIPITATION IS FAVORED FOR PARTS OF THE GREAT LAKES AND NORTHEAST IN
ASSOCIATION WITH A MEAN 500-HPA TROUGH. THERE ARE INCREASED ODDS OF NEAR TO
ABOVE NORMAL PRECIPITATION FOR THE SOUTHERN FLORIDA PENINSULA UNDERNEATH MEAN
EASTERLY FLOW. PROBABILITIES OF NEAR TO ABOVE NORMAL PRECIPITATION ARE ALSO
ELEVATED FOR PARTS OF THE NORTHWESTERN CONUS AS THE RIDGE OVER THE WESTERN
CONUS POTENTIALLY DE-AMPLIFIES DURING THE WEEK-2 PERIOD. THE TROUGH FORECAST
OVER ALASKA LEADS TO INCREASED ODDS OF ABOVE NORMAL PRECIPITATION FOR MUCH OF
THE STATE.

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 30% OF YESTERDAY`S OPERATIONAL
18Z GFS CENTERED ON DAY 10, AND 70% 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 SPREAD AMONG THE ENSEMBLE MEMBERS OVER MOST OF THE FORECAST DOMAIN.

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
NOVEMBER 16

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:
20050929 - 20011030 - 19531101 - 19751102 - 19640929


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:
20050928 - 20011030 - 19751101 - 19991007 - 19541008


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 25 - 29 2017

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



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 27 - NOV 02, 2017

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