Prognostic Meteorological Discussion
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FXUS06 KWBC 042001
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT MON MAY 04 2015

6-10 DAY OUTLOOK FOR MAY 10 - 14 2015

THE AVAILABLE MODELS EXHIBIT GOOD AGREEMENT ON THE 500-HPA HEIGHT FIELD OVER
NORTH AMERICA. MOST MODELS DEPICT A TROUGH-RIDGE-TROUGH PATTERN OVER THE
EASTERN PACIFIC AND ALASKA, WITH TROUGHING THEN EXTENDING ACROSS THE SOUTHWEST
QUADRANT OF THE CONUS. ABOVE NORMAL HEIGHTS ARE FORECAST OVER THE EASTERN THIRD
OF THE CONUS IN ALL MODELS, EXCEPT THE 6Z DETERMINISTIC GFS, WHICH MOVES THE
ABOVE NORMAL HEIGHTS OVER THE ATLANTIC.

THE AVAILABLE MODELS DIFFER SLIGHTLY IN THE POSITION OF THE RIDGE OVER WESTERN
NORTH AMERICA, WITH THE EUROPEAN ENSEMBLE MEAN DEPICTING LOWER HEIGHTS OVER
BRITISH COLUMBIA. THE GFS-BASED AND CANADIAN MODELING SYSTEM SOLUTIONS DEPICT
RIDGING THAT EXTENDS FROM CANADA ACROSS THE GREAT LAKES, WHILE THE
DETERMINISTIC ECMWF SOLUTIONS BREAK THE AREA OF ABOVE NORMAL HEIGHTS OVER THE
NORTHERN GREAT PLAINS.

THE 0Z GFS ENSEMBLE MEAN IS THE LARGEST CONSTITUENT IN THE THE 500-HPA HEIGHT
MANUAL BLEND, AS THAT MODEL HAD THE HIGHEST COMBINED ANALOG CORRELATION SCORE
AND ANOMALY CORRELATION SCORE. THE 0Z ECMWF ENSEMBLE MEAN HAS THE HIGHEST
COMBINED ANALOG AND ANOMALY CORRELATIONS SCORES FROM NON-GFS MODELS, SO IT IS
INCLUDED AS WELL. TELECONNECTIONS ON THE POSITIVE HEIGHT CENTER OVER NORTHERN
CANADA WOULD FAVOR NEAR TO SLIGHTLY BELOW NORMAL HEIGHTS OVER THE CENTRAL
PORTIONS OF THE CONUS, WHICH ALIGNS WITH THE ENSEMBLE MEAN SOLUTIONS, SO NO
DETERMINISTIC SOLUTIONS ARE INCLUDED.

THE RESULTANT 500-HPA PATTERN CONTAINS ABOVE NORMAL HEIGHTS, WHICH FAVORS ABOVE
NORMAL TEMPERATURES, OVER ALASKA. MID-LEVEL TROUGHING AND STRONG SURFACE
RIDGING NEAR THE WEST COAST FAVORS BELOW NORMAL TEMPERATURS ALONG THE IMMEDIATE
WEST COAST. THE POTENTIAL FOR SOME LATE SEASON COOLER AIR TO MOVE SOUTHWARD
FROM CANADA FAVORS BELOW NORMAL TEMPERATURES OVER THE NORTH CENTRAL CONUS WHILE
ABOVE MEDIAN PRECIPITATION FAVORS BELOW NORMAL TEMPERATURES OVER THE SOUTHERN
GREAT PLAINS AND PORTIONS OF SOUTHWEST. SURFACE AND UPPER-LEVEL RIDGING FAVOR
ABOVE NORMAL TEMPERATURES FOR THE EASTERN THIRD OF THE CONUS.

ABOVE MEDIAN PRECIPITATION IS FAVORED FOR MUCH OF THE CONUS DUE TO TROUGHING
NEAR THE WEST COAST AND A MEAN SOUTHEASTERLY LOW-LEVEL FLOW INTO THE GREAT
PLAINS.  SOME UNCERTAINTY ABOUT TOTAL PRECIPITATION AMOUNTS EXISTS FOR THE
MID-WEST, AS ANY AIR MASS THAT MOVES FROM CANADA WOULD LIKELY BRING DRIER AIR.

TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 35% OF TODAY`S 0Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8, 20% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 30%
OF TODAY`S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8, AND 15% OF TODAY`S 0Z
CANADIAN 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 MODEL SOLUTIONS, TEMPERED BY DISAGREEMENT ON THE
PREDICTED PRECIPITATION PATTERN.

8-14 DAY OUTLOOK FOR MAY 12 - 18 2015

THE MODELS CONTINUE TO EXHIBIT GOOD AGREEMENT ON THE 500-HPA HEIGHT PATTERN
OVER NORTH AMERICA DURING THE 8-14 DAY PERIOD.  MOST MODEL SOLUTIONS DEPICT
ABOVE NORMAL HEIGHTS STRETCHING FROM ALASKA, ACROSS CANADA TO THE NORTHEAST,
WITH TROUGHING AND BELOW NORMAL HEIGHTS WEST OF THE CONTINENTAL DIVIDE.

THE SOLUTIONS FROM THE ECMWF ARE SLIGHTLY MORE AMPLIFIED WITH THE TROUGH NEAR
THE WEST COAST, RESULTING IN A MORE WESTWARD DISPLACEMENT OF THE AREA OF ABOVE
NORMAL HEIGHTS OVER THE NORTHEAST. THE GFS-BASED SOLUTIONS ARE THE MOST
PROGRESSIVE, WITH THE CANADIAN ENSEMBLE MEANS LEANING TOWARD THE ECWMF
SOLUTIONS. TELECONNECTIONS ON THE ANOMALOUS CIRCULATION CENTERS IN THE MODEL
FIELDS DO NOT ALIGN WELL WITH THE MODEL OUTPUTS, INTRODUCING UNCERTAINTY INTO
THE OUTLOOK. THE 500-HPA HEIGHT MANUAL BLEND IS A 50/50 SPLIT BETWEEN GFS AND
ECWMF/CANADIAN, DUE IN PART TO THE UNCERTAINTY REGARDING THE ALIGNMENT WITH
HISTORICAL OBSERVATIONS. DISAGREEMENT AMONG THE TOOLS IS ELEVATED, WITH ANALOG
FORECASTS FROM THE MANUAL BLEND NOT ALIGNING WELL WITH OTHER SPECIFICATION
TOOLS OR CALIBRATED DYNAMICAL MODEL OUTPUTS.

THE PREDICTED 500-HPA PATTERN FAVORS BELOW NORMAL TEMPERATURES FROM CALIFORNIA
TO TEXAS, WITH ABOVE NORMAL TEMPERATURES FROM THE PACIFIC NORTHWEST TO THE
NORTHERN GREAT PLAINS. MOST TOOLS FAVOR ABOVE NORMAL TEMPERATURES FROM THE
MISSISSIPPI RIVER TO THE EAST COAST, ALTHOUGH THERE IS INCREASED UNCERTAINTY
ABOUT THE IMPACT OF A LATE SEASON COLD FRONT ACROSS THE GREAT LAKES AND
NORTHEAST.

TROUGHING FROM THE WEST COAST TO THE SOUTHERN GREAT PLAINS IMPLIES AN ACTIVE
SOUTHERN STORM TRACK, WHICH FAVORS ABOVE MEDIAN PRECIPITATION FOR MUCH OF THE
ROCKIES, HIGH PLAINS, AND SOUTHERN GREAT PLAINS.  MEAN SURFACE HIGH PRESSURE
FAVORS BELOW MEDIAN PRECIPITATION FOR THE GREAT LAKES AND OHIO VALLEY, WHILE
THE POSSIBILITY OF A STALLED FRONT ELEVATES ODDS FOR ABOVE MEDIAN PRECIPITATION
ACROSS THE SOUTHEAST.

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 20% OF TODAY`S 0Z GFS ENSEMBLE
MEAN CENTERED ON DAY 11, 30% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY
11, 30% OF TODAY`S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, AND 20% OF
TODAY`S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 11


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: AVERAGE, 3 OUT OF 5, DUE TO
GOOD AGREEMENT AMONG THE MODELS BUT DISAGREEMENT AMONG THE TOOLS AND POOR
ALIGNMENT WITH TELECONNECTIONS.

FORECASTER: MATT ROSENCRANS

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 MAY
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:
19820505 - 19620504 - 19550503 - 19590505 - 19920508


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:
20090422 - 19620504 - 19590504 - 19820505 - 19550503


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 10 - 14 2015

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



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 12 - 18 2015

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