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FXUS06 KWBC 242000
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EST WED DECEMBER 24 2014

6-10 DAY OUTLOOK FOR DEC 30, 2014 - JAN 03, 2015

TODAY`S MODEL SOLUTIONS CONTINUE TO DIFFER ON THE ORIENTATION OF THE LONGWAVE
TROUGH AXIS EXPECTED ACROSS THE LOWER 48. MODEL CONTINUITY AMONG THE HIGH
RESOLUTION MODEL RUNS IS POOR RANGING FROM YESTERDAY`S 12Z SOLUTIONS FEATURING
A FULL LATITUDE TROUGH CENTERED OVER THE EAST-CENTRAL CONUS, TO TODAY`S 0Z
SOLUTIONS DEPICTING A POSITIVELY TILTED TROUGH EXTENDING FROM HUDSON BAY
SOUTHWEST TO NORTHERN MEXICO. DUE TO THE LACK OF CONTINUITY, NO HIGH RESOLUTION
MODEL RUNS ARE USED IN CREATING THE 500-HPA BLEND.  TELECONNECTIONS ON A WELL
AGREED UPON POSITIVE 500-HPA HEIGHT ANOMALY CENTER NEAR BRITISH COLUMBIA AT
50N-140W DOES NOT FAVOR THE PROGRESSIVE LONGWAVE TROUGH PREDICTED BY THE 0Z
CANADIAN ENSEMBLE MEAN. THE 500-HPA MANUAL BLEND IS CREATED USING THE 0Z/6Z GFS
AND 0Z ECMWF ENSEMBLE MEANS WHICH MAINTAINS GOOD CONTINUITY WITH YESTERDAY`S
MANUAL BLEND AND IS SUPPORTED BY THE AFOREMENTIONED TELECONNECTION.

DESPITE UNCERTAINTY ON THE ORIENTATION OF THE LONGWAVE TROUGH AXIS, TEMPERATURE
TOOLS INCLUDING GUIDANCE DERIVED FROM THE TELECONNECTION FAVOR BELOW-NORMAL
TEMPERATURES FOR A MAJORITY OF THE CONUS. THE HIGHEST ODDS FOR BELOW-NORMAL
TEMPERATURES ARE FORECAST ACROSS THE CENTRAL ROCKIES AND CENTRAL/SOUTHERN
PLAINS WHERE A 1048-HPA OR STRONGER SURFACE HIGH IS EXPECTED TO BUILD SOUTH
EARLY IN THE PERIOD. NEAR NORMAL TEMPERATURES ARE FAVORED FOR PARTS OF
CALIFORNIA WHERE A WARMING TREND IS EXPECTED LATER IN THIS PERIOD, WHILE A
SHIFTING TEMPERATURE PATTERN FAVORS NEAR NORMAL TEMPERATURES FOR THE FLORIDA
PENINSULA AND COASTAL SOUTHEAST.

SINCE THE NORTHERN STREAM IS EXPECTED TO BECOME MORE DOMINANT BY THE NEW YEAR,
A DRIER PATTERN IS LIKELY FOR MUCH OF THE CONUS BY EARLY JANUARY. A LOW
PRESSURE SYSTEM IS EXPECTED TO RAPIDLY EXIT THE EAST COAST BY DAY 6 WITH LITTLE
OR NO EFFECT ON THE PRECIPITATION OUTLOOK. THE LACK OF A BLOCKING RIDGE OF HIGH
PRESSURE OVER THE NORTH ATLANTIC IS LIKELY TO RESULT IN FAST-MOVING AND
RELATIVELY WEAK LOW PRESSURE SYSTEMS FOR THE EAST COAST. THEREFORE, NEAR TO
BELOW-MEDIAN PRECIPITATION IS FAVORED ACROSS THE NORTHEAST. UPSLOPE FLOW EARLY
IN THE PERIOD TILTS THE ODDS TOWARDS ABOVE-MEDIAN PRECIPITATION ACROSS
SOUTHEAST COLORADO AND EASTERN NEW MEXICO. LATER IN THE PERIOD, A SLOW RETURN
OF LOW-LEVEL MOISTURE AND THE POTENTIAL FOR CYCLOGENESIS NEAR THE GULF COAST
FAVOR NEAR TO ABOVE-MEDIAN PRECIPITATION ACROSS THE GULF COAST STATES AND PARTS
OF THE SOUTHEAST. THE UPPER-LEVEL RIDGE FORECAST UPSTREAM OVER THE NORTHEAST
PACIFIC FAVORS BELOW-MEDIAN PRECIPITATION FOR THE WESTERN CONUS.

ANOMALOUS SOUTHERLY FLOW AND ABOVE-NORMAL 500-HPA HEIGHTS INCREASE CHANCES FOR
ABOVE-NORMAL TEMPERATURES ACROSS ALASKA. 5-DAY PRECIPITATION AMOUNTS FROM THE
0Z GFS AND 0Z ECMWF ENSEMBLE MEANS ARE DECREASING FROM PREVIOUS MODEL RUNS
WHICH IS CONSISTENT WITH FORECASTS OF A BUILDING 500-HPA RIDGE. THE TROUGH OVER
THE BERING SEA INCREASES CHANCES FOR ABOVE-MEDIAN PRECIPITATION ACROSS WESTERN
ALASKA.

TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 25% OF TODAY`S 0Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8, 25% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, AND
50% OF TODAY`S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 8


MODEL OF THE DAY: 0Z ECMWF ENSEMBLE MEAN

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO GOOD
AGREEMENT AMONG THE TEMPERATURE TOOLS OFFSET BY POOR CONTINUITY AMONG THE HIGH
RESOLUTION MODEL RUNS AND INCREASING ENSEMBLE SPREAD ACROSS THE NORTHEAST
PACIFIC.

8-14 DAY OUTLOOK FOR JAN 01 - 07 2015

THE 0Z/6Z GFS AND 0Z ECMWF ENSEMBLE MEANS INDICATE THAT THE AMPLIFIED RIDGE
OVER THE NORTHEAST PACIFIC SHIFTS SLIGHTLY NORTHWEST, BUT THEIR INDIVIDUAL
ENSEMBLE MEMBERS INDICATE A LARGE SPREAD ON THE POSITION AND AMPLITUDE OF THIS
FEATURE. 500-HPA HEIGHTS ARE FORECAST TO INCREASE ACROSS THE SOUTHEASTERN CONUS
AMONG THE 0Z/6Z GFS AND 0Z ECMWF ENSEMBLE MEANS. A BROAD TROUGH OVER THE CONUS
IS PREDICTED BY THESE ENSEMBLE MEANS, BUT THE 0Z/6Z GFS ENSEMBLE MEANS FEATURE
LOWER 500-HPA HEIGHTS ACROSS THE WESTERN CONUS THAN DEPICTED BY THE 0Z ECMWF
ENSEMBLE MEAN.

AN INCREASE IN 500-HPA HEIGHTS, A CONSISTENT SIGNAL AMONG MODEL GUIDANCE,
ACROSS MUCH OF THE LOWER 48 FAVORS LESS COVERAGE AND LOWER PROBABILITIES OF
BELOW-NORMAL TEMPERATURES ACROSS THE CONUS COMPARED TO THE 6-10 DAY PERIOD. IT
SHOULD BE NOTED THAT THE INCREASE IN 500-HPA HEIGHTS CAN ALSO BE CONTRIBUTING
TO THE INCREASE SPREAD AMONG ENSEMBLE MEMBERS. THE MOST LIKELY AREA TO
EXPERIENCE A WARMING TREND DURING WEEK-2 IS THE SOUTHEAST AS 0Z/6Z GFS AND 0Z
ECMWF ENSEMBLE MEANS DEPICT ABOVE-NORMAL 500-HPA HEIGHTS ACROSS THIS REGION.

THE EASING OF ANOMALOUS NORTHERLY FLOW ACROSS THE LOWER 48 IS EXPECTED TO FAVOR
A WETTER PATTERN FOR THE EASTERN THIRD OF THE CONUS DURING WEEK-2. HOWEVER, THE
PRECIPITATION SIGNAL AMONG VARIOUS TOOLS IS GENERALLY WEAK. THE MOST FAVORED
AREA FOR ABOVE-MEDIAN PRECIPITATION INCLUDE EAST TEXAS, THE LOWER MISSISSIPPI
VALLEY, SOUTHEAST, AND MID-ATLANTIC WHERE THE 6Z GFS AND 0Z ECMWF MODELS
INDICATE 0.75 INCHES OR MORE OF PRECIPITATION DURING WEEK-2. A NORTHWEST SHIFT
OF THE UPPER-LEVEL RIDGE AWAY FROM THE WEST COAST SIGNALS A POTENTIAL CHANGE
WITH AN INCREASE IN ONSHORE FLOW AND MORE SEASONAL PRECIPITATION FOR THE WEST
COAST BY THE END OF WEEK-2. THEREFORE, PROBABILITIES FOR BELOW-MEDIAN
PRECIPITATION CONTINUE TO DECREASE FOR THIS REGION COMPARED TO PREVIOUS DAY`S
OUTLOOKS.

ANOMALOUS SOUTHERLY FLOW EARLY IN WEEK-2 FAVORS ABOVE-NORMAL TEMPERATURES
ACROSS THE ALEUTIANS AND WESTERN ALASKA. NEAR TO BELOW-MEDIAN PRECIPITATION IS
FAVORED FOR ALASKA DUE TO THE STRENGTHENING UPPER-LEVEL RIDGE.

THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 20% OF TODAY`S 0Z GFS ENSEMBLE
MEAN CENTERED ON DAY 11, 20% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY
11, AND 60% 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 CONTINUED POOR MODEL CONTINUITY AND LARGE SPREAD AMONG THE 6Z AND 0Z ECMWF
ENSEMBLE MEMBERS.

FORECASTER: BRAD PUGH

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
JANUARY 15

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:
19581229 - 19591227 - 19751228 - 19991206 - 19731207


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:
19731206 - 19581229 - 19991205 - 19991212 - 19751228


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 30, 2014 - JAN 03, 2015

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



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR JAN 01 - 07 2015

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