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FXUS06 KWBC 181901
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT WED OCTOBER 18 2017

6-10 DAY OUTLOOK FOR OCT 24 - 28 2017

TODAY`S ENSEMBLE MEAN SOLUTIONS ARE IN VERY GOOD AGREEMENT ON AN AMPLIFIED FLOW
PATTERN OVER MOST OF THE FORECAST DOMAIN. A DEEP, CLOSED 500-HPA TROUGH IS
FORECAST OVER PARTS OF WESTERN ALASKA. DOWNSTREAM A STRONG RIDGE IS PREDICTED
OVER THE WESTERN HALF OF THE CONUS. A TROUGH IS FORECAST OVER THE EASTERN HALF
OF THE CONUS. TODAY`S 500-HPA MANUAL BLEND FEATURES NEGATIVE HEIGHT ANOMALIES
OVER MOST OF ALASKA, POSITIVE HEIGHT ANOMALIES OVER THE WESTERN HALF OF THE
CONUS, AND NEGATIVE HEIGHT ANOMALIES OVER THE EASTERN HALF OF THE CONUS.

BELOW NORMAL TEMPERATURES ARE FAVORED FOR PARTS OF WESTERN ALASKA DUE TO A DEEP
TROUGH PREDICTED OVER PARTS OF WESTERN ALASKA. 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,
WHERE THE PREDICTED RIDGE IS CENTERED. 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 DEEPENING TROUGH AND COLD
AIR ADVECTION BEHIND A FRONTAL PASSAGE INCREASE THE LIKELIHOOD OF BELOW NORMAL
TEMPERATURES FOR PARTS OF THE EASTERN U.S. IN PARTS OF THE NORTHEAST, LARGE
POSITIVE TEMPERATURE ANOMALIES FORECAST DURING THE FIRST HALF OF THE PERIOD
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 THE ALEUTIANS, THE SOUTHERN ALASKA COAST, THE ALASKA PANHANDLE, 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 COUNTRY NEAR AND WEST OF THE
MISSISSIPPI RIVER. A FRONTAL PASSAGE PREDICTED NEAR THE BEGINNING OF THE 6-10
DAY PERIOD INCREASES THE LIKELIHOOD OF ABOVE NORMAL PRECIPITATION FOR PARTS OF
EASTERN U.S.

TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 50% OF TODAY`S 6Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8, AND 50% OF TODAY`S OPERATIONAL 0Z ECMWF 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 AND FAIRLY GOOD AGREEMENT AMONG THE TEMPERATURE
AND PRECIPITATION TOOLS.

8-14 DAY OUTLOOK FOR OCT 26 - NOV 01, 2017

DURING THE WEEK-2 PERIOD, THE OVERALL 500-HPA FLOW PATTERN IS EXPECTED SHIFT
SLIGHTLY EASTWARD, AND BE LESS AMPLIFIED. TODAY`S MODELS SIGNIFICANTLY WEAKEN
THE EASTERN TROUGH DURING THE WEEK-2 PERIOD, PREDICTING A MORE PROGRESSIVE
PATTERN ACROSS MUCH OF THE CONUS.

THE TEMPERATURE PROBABILITIES FORECAST DURING THE 6-10 DAY PERIOD ARE VERY
SIMILAR TO THOSE FORECAST DURING THE WEEK-2 PERIOD, WITH A COUPLE OF
EXCEPTIONS. PROBABILITIES ARE SOMEWHAT LOWER ACROSS THE COUNTRY DUE TO THE
INCREASED UNCERTAINTY DURING THE WEEK-2 PERIOD, A MORE PROGRESSIVE PATTERN, AND
SMALLER FORECAST 500-HPA HEIGHT ANOMALIES. THE TEMPERATURE PROBABILITIES ARE
ALSO SHIFTED SLIGHTLY EASTWARD, COINCIDING WITH THE EXPECTED EASTWARD SHIFT IN
THE LARGE-SCALE PATTERN.

THE PRECIPITATION PROBABILITIES FORECAST DURING THE 6-10 DAY PERIOD ARE SIMILAR
TO THE WEEK-2 PERIOD, EXCEPT THAT THE FRONTAL SYSTEM FORECAST TO FAVOR ABOVE
NORMAL PRECIPITATION IN THE EASTERN U.S. DURING THE 6-10 DAY PERIOD IS
PREDICTED TO MOVE OFFSHORE BEFORE THE WEEK-2 PERIOD BEGINS, EXPANDING THE
FAVORED NEAR TO BELOW NORMAL PRECIPITATION INTO THE EASTERN U.S. THE EXCEPTION
TO THIS IS THE FLORIDA PENINSULA, WHERE A FORECAST PERSISTENT SURFACE FRONT
INCREASES THE CHANCES FOR ABOVE NORMAL PRECIPITATION THERE.

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 50% OF TODAY`S OPERATIONAL 6Z
GFS CENTERED ON DAY 11, AND 50% OF TODAY`S 0Z EUROPEAN ENSEMBLE MEAN CENTERED
ON DAY 11


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOVE AVERAGE, 4 OUT OF 5, DUE
TO GOOD AGREEMENT AMONG THE MODELS AND FAIRLY GOOD AGREEMENT AMONG THE
TEMPERATURE AND PRECIPITATION TOOLS.

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:
20071030 - 20050928 - 19781029 - 20011030 - 19541009


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:
20050927 - 19781030 - 20011030 - 20071031 - 19541008


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

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  A    B     OREGON      A    B     NRN CALIF   A    B
SRN CALIF   A    B     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    N    B
N TEXAS     B    B     S TEXAS     B    B     W TEXAS     A    B
MINNESOTA   N    B     IOWA        N    B     MISSOURI    B    B
ARKANSAS    B    B     LOUISIANA   B    B     WISCONSIN   N    B
ILLINOIS    B    B     MISSISSIPPI B    B     MICHIGAN    N    A
INDIANA     B    B     OHIO        B    A     KENTUCKY    B    A
TENNESSEE   B    B     ALABAMA     B    N     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        A    A     NEW JERSEY  A    A     W VIRGINIA  B    A
MARYLAND    N    A     DELAWARE    A    A     VIRGINIA    B    A
N CAROLINA  B    A     S CAROLINA  B    A     GEORGIA     B    A
FL PNHDL    B    A     FL PENIN    B    A     AK N SLOPE  N    N
AK ALEUTIAN B    A     AK WESTERN  B    N     AK INT BSN  A    N
AK S INT    A    A     AK SO COAST A    A     AK PNHDL    A    A



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR OCT 26 - NOV 01, 2017

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