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000
FXUS01 KWBC 242033
PMDSPD

SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
433 PM EDT FRI APR 24 2015

VALID 00Z SAT APR 25 2015 - 00Z MON APR 27 2015

...THERE IS A RISK OF SEVERE WEATHER FOR PARTS OF THE SOUTHERN
PLAINS/LOWER MISSISSIPPI VALLEY/TENNESSEE VALLEY/SOUTHEAST...

...COOL WEATHER WILL CONTINUE ACROSS THE NORTHEAST/GREAT LAKES AND
SPREAD ACROSS THE NORTHWEST US....

...RAIN WILL BE WIDESPREAD ACROSS MANY REGIONS OF THE COUNTRY
FOCUSING ON THE MIDDLE ATLANTIC STATES/OHIO VALLEY/MID MISSISSIPPI
VALLEY AND MUCH OF THE ROCKIES WITH MOUNTAIN SNOW...

A VERY SLOW MOVING WEATHER PATTERN WILL COVER MUCH OF THE COUNTRY
WITH A COUPLE OF STORM SYSTEMS BRINGING THE POSSIBILITY OF SEVERE
WEATHER, INCLUDING SEVERE THUNDERSTORMS, HAIL AND A FEW TORNADOES
OVER THE WEEKEND INTO MONDAY.

ONE STORM SYSTEM WILL MOVE FROM THE CENTRAL PLAINS EASTWARD ACROSS
THE OHIO VALLEY AND THE MIDDLE ATLANTIC STATES THROUGH SUNDAY.
SEVERE THUNDERSTORMS ARE POSSIBLE WITH THIS SYSTEM FROM THE
SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY INTO SATURDAY AND
ACROSS THE TENNESSEE AND LOWER OHIO VALLEY INTO THE SOUTHEAST INTO
SUNDAY. ON THE NORTHERN EDGE OF THE STORM, A CHILLY RAIN WILL FALL
ACROSS THE MIDWEST AND UPPER OHIO VALLEY INTO THE MID ATLANTIC
STATES.

COOL WEATHER WILL CONTINUE TO PREVAIL ACROSS THE NORTHEAST AND
MIDWEST AND ONCE THIS FIRST STORM SYSTEM MOVES ACROSS, COOLER
TEMPERATURES WILL FOLLOW ACROSS THE LOW MISSISSIPPI VALLEY INTO
TENNESSEE VALLEY AND SOUTHERN ATLANTIC STATES.

ACROSS THE WESTERN HALF OF THE COUNTRY A COLD FRONT WILL WORK ITS
WAY SLOWLY SOUTH AND EASTWARD AND COOLER AIR WILL FOLLOW IN ITS
WAKE.  RAIN AND SNOW AT HIGHER ELEVATIONS WILL COVER MUCH OF THE
WESTERN US WITH SOME OF THE HEAVIER TOTALS IN MOUNTAINOUS AREAS OF
NORTHERN CALIFORNIA, UTAH, WYOMING, MONTANA AND COLORADO WHERE
RAINFALL OF .5 INCHES TO GREATER THAN AN INCH WILL FALL OVER THE
NEXT FEW DAYS.  SNOW WILL ALSO FALL ACROSS PORTIONS OF THE SIERRA,
THE WASATCH MOUNTAINS IN UTAH, ACROSS NORTHWESTERN WYOMING,
WESTERN MONTANA AND ACROSS PARTS OF IDAHO, AS WELL AS ACROSS THE
HIGHER PEAKS OF THE COLORADO ROCKIES.


KOCIN


GRAPHICS AVAILABLE AT WWW.WPC.NCEP.NOAA.GOV
$$







000
FXUS01 KWBC 242033
PMDSPD

SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
433 PM EDT FRI APR 24 2015

VALID 00Z SAT APR 25 2015 - 00Z MON APR 27 2015

...THERE IS A RISK OF SEVERE WEATHER FOR PARTS OF THE SOUTHERN
PLAINS/LOWER MISSISSIPPI VALLEY/TENNESSEE VALLEY/SOUTHEAST...

...COOL WEATHER WILL CONTINUE ACROSS THE NORTHEAST/GREAT LAKES AND
SPREAD ACROSS THE NORTHWEST US....

...RAIN WILL BE WIDESPREAD ACROSS MANY REGIONS OF THE COUNTRY
FOCUSING ON THE MIDDLE ATLANTIC STATES/OHIO VALLEY/MID MISSISSIPPI
VALLEY AND MUCH OF THE ROCKIES WITH MOUNTAIN SNOW...

A VERY SLOW MOVING WEATHER PATTERN WILL COVER MUCH OF THE COUNTRY
WITH A COUPLE OF STORM SYSTEMS BRINGING THE POSSIBILITY OF SEVERE
WEATHER, INCLUDING SEVERE THUNDERSTORMS, HAIL AND A FEW TORNADOES
OVER THE WEEKEND INTO MONDAY.

ONE STORM SYSTEM WILL MOVE FROM THE CENTRAL PLAINS EASTWARD ACROSS
THE OHIO VALLEY AND THE MIDDLE ATLANTIC STATES THROUGH SUNDAY.
SEVERE THUNDERSTORMS ARE POSSIBLE WITH THIS SYSTEM FROM THE
SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY INTO SATURDAY AND
ACROSS THE TENNESSEE AND LOWER OHIO VALLEY INTO THE SOUTHEAST INTO
SUNDAY. ON THE NORTHERN EDGE OF THE STORM, A CHILLY RAIN WILL FALL
ACROSS THE MIDWEST AND UPPER OHIO VALLEY INTO THE MID ATLANTIC
STATES.

COOL WEATHER WILL CONTINUE TO PREVAIL ACROSS THE NORTHEAST AND
MIDWEST AND ONCE THIS FIRST STORM SYSTEM MOVES ACROSS, COOLER
TEMPERATURES WILL FOLLOW ACROSS THE LOW MISSISSIPPI VALLEY INTO
TENNESSEE VALLEY AND SOUTHERN ATLANTIC STATES.

ACROSS THE WESTERN HALF OF THE COUNTRY A COLD FRONT WILL WORK ITS
WAY SLOWLY SOUTH AND EASTWARD AND COOLER AIR WILL FOLLOW IN ITS
WAKE.  RAIN AND SNOW AT HIGHER ELEVATIONS WILL COVER MUCH OF THE
WESTERN US WITH SOME OF THE HEAVIER TOTALS IN MOUNTAINOUS AREAS OF
NORTHERN CALIFORNIA, UTAH, WYOMING, MONTANA AND COLORADO WHERE
RAINFALL OF .5 INCHES TO GREATER THAN AN INCH WILL FALL OVER THE
NEXT FEW DAYS.  SNOW WILL ALSO FALL ACROSS PORTIONS OF THE SIERRA,
THE WASATCH MOUNTAINS IN UTAH, ACROSS NORTHWESTERN WYOMING,
WESTERN MONTANA AND ACROSS PARTS OF IDAHO, AS WELL AS ACROSS THE
HIGHER PEAKS OF THE COLORADO ROCKIES.


KOCIN


GRAPHICS AVAILABLE AT WWW.WPC.NCEP.NOAA.GOV
$$






000
FXUS06 KWBC 241902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT FRI APRIL 24 2015

6-10 DAY OUTLOOK FOR APR 30 - MAY 04, 2015

TODAY`S ENSEMBLE MODEL SOLUTIONS ARE IN FAIRLY GOOD AGREEMENT ON THE 500-HPA
FLOW PATTERN EXPECTED OVER MUCH OF NORTH AMERICA AND VICINITY. ALL MODELS ARE
FORECASTING A TROUGH OVER THE GULF OF ALASKA OFF THE WEST COAST OF NORTH
AMERICA AND A RIDGE OVER THE CENTRAL CONUS. FARTHER TO THE EAST, A TROUGH IS
PREDICTED BY ALL OF TODAY`S MODEL SOLUTIONS NEAR THE EAST COAST OF NORTH
AMERICA WITH NEGATIVE 500-HPA HEIGHT ANOMALIES FORECAST OVER THE EASTERN CONUS.
THE ENSEMBLE SPAGHETTI DIAGRAMS INDICATE MODERATE SPREAD ACROSS THE FORECAST
DOMAIN.

BELOW NORMAL TEMPERATURES ARE FAVORED FOR MOST OF THE EASTERN OF CONUS AND THE
COASTAL PLAINS IN ASSOCIATION WITH BELOW NORMAL 500-HPA HEIGHTS. RIDGING OVER
CENTRAL NORTH AMERICA INCREASES THE CHANCES FOR ABOVE NORMAL TEMPERATURES FOR
THE WESTERN AND CENTRAL CONUS INCLUDE ALASKA, THE ALEUTIANS AND THE ALASKA
PANHANDLE.

BELOW MEDIAN PRECIPITATION IS FAVORED FOR THE CENTRAL AND EASTERN CONUS DUE TO
DESCENT EXPECTED ON THE WESTERN SIDE OF THE TROUGH FORECAST OVER THE EASTERN
U.S. AND THE WEST-CENTRAL CONUS IN ASSOCIATION WITH THE RIDGE OVER CENTRAL AND
WESTERN NORTH AMERICA.  ABOVE MEDIAN PRECIPITATION IS FAVORED FOR NEW MEXICO,
CONSISTENT WITH PRECIPITATION ESTIMATES FROM THE GFS AND ECMWF CALIBRATED
REFORECAST TOOLS. THERE ARE ENHANCED CHANCES OF BELOW MEDIAN PRECIPITATION FOR
ALASKA WEST OF A TROUGH PREDICTED OVER THE GULF OF ALASKA. THE TROUGH OVER THE
GULF OF ALASKA ENHANCES PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION FOR THE
ALASKA PANHANDLE.

TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 10% OF TODAY`S 0Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8, 20% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 20%
OF TODAY`S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 8, 20% OF TODAY`S 0Z EUROPEAN
ENSEMBLE MEAN CENTERED ON DAY 8, 10% OF YESTERDAY`S 12Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 7, AND 20% OF TODAY`S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY
8


MODEL OF THE DAY: NO PREFERENCE

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
FAIRLY GOOD ENSEMBLE MEAN AGREEMENT.

8-14 DAY OUTLOOK FOR MAY 02 - 08 2015

TODAY`S WEEK TWO ENSEMBLE MEAN SOLUTIONS DEPICT A MEAN 500-HPA TROUGH OVER THE
GULF OF ALASKA MOVING EASTWARD COMPARED TO YESTERDAY`S PATTERN. A TROUGH IS
FORECAST OVER THE WEST COAST WITH A RIDGE OVER WESTERN CANADA AND MUCH OF THE
CENTRAL CONUS.

ABOVE NORMAL TEMPERATURE PROBABILITIES ARE ENHANCED FOR ALASKA, THE ALEUTIANS,
THE ALASKA PANHANDLE, AND MUCH OF THE CONUS IN ASSOCIATION WITH POSITIVE
500-HPA HEIGHT ANOMALIES AND THE RIDGE FORECAST OVER THE CENTRAL CONUS. WITH
THE YESTERDAY`S TROUGH OVER THE EASTERN CONUS MOVING OVER THE ATLANTIC AND THE
MEAN RIDGE MOVING EASTWARD, ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR THE GULF
COAST, ALSO INFLUENCED BY THE POSITIVE SEA SURFACE TEMPERATURE ANOMALIES.

PROBABILITIES OF BELOW MEDIAN PRECIPITATION ARE ENHANCED WEST OF THE PREDICTED
TROUGH FOR THE PARTS OF OHIO AND TENNESSEE VALLEYS, AND THE MID-ATLANTIC COAST.
ENHANCED PROBABILITIES OF ABOVE MEDIAN PRECIPITATION ARE INDICATED FOR THE
GREAT PLAINS, THE ROCKIES AND THE GREAT BASIN IN ASSOCIATION WITH A MEAN TROUGH
PREDICTED OVER THE WEST COAST. ABOVE MEDIAN PRECIPITATION IS ALSO FAVORED FOR
THE GULF COAST, CONSISTENT WITH PRECIPITATION ESTIMATES FROM THE GFS AND ECMWF
CALIBRATED REFORECAST TOOLS. THERE ARE ENHANCED PROBABILITIES OF BELOW MEDIAN
PRECIPITATION FOR EASTERN ALASKA AND THE ALASKA PANHANDLE DUE TO THE
EXPECTATION OF ABOVE NORMAL 500-HPA HEIGHTS.


THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 20% OF TODAY`S 6Z GFS ENSEMBLE
MEAN CENTERED ON DAY 11, 20% OF TODAY`S GFS SUPERENSEMBLE MEAN CENTERED ON DAY
11, 20% OF TODAY`S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, 20% OF
YESTERDAY`S 12Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 10, 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
RELATIVELY GOOD AGREEMENT AMONG THE ENSEMBLE MEAN SOLUTIONS OFFSET BY LARGE
SPREAD AMONG THE COMPONENT ENSEMBLE MEMBERS OVER MUCH OF NORTH AMERICA

FORECASTER: QIN GINGER ZHANG

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:
19880419 - 20080508 - 19800508 - 20090408 - 19730428


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:
19880419 - 20080507 - 19790407 - 20090408 - 19730427


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR APR 30 - MAY 04, 2015

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



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 02 - 08 2015

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

$$






000
FXUS06 KWBC 241902
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT FRI APRIL 24 2015

6-10 DAY OUTLOOK FOR APR 30 - MAY 04, 2015

TODAY`S ENSEMBLE MODEL SOLUTIONS ARE IN FAIRLY GOOD AGREEMENT ON THE 500-HPA
FLOW PATTERN EXPECTED OVER MUCH OF NORTH AMERICA AND VICINITY. ALL MODELS ARE
FORECASTING A TROUGH OVER THE GULF OF ALASKA OFF THE WEST COAST OF NORTH
AMERICA AND A RIDGE OVER THE CENTRAL CONUS. FARTHER TO THE EAST, A TROUGH IS
PREDICTED BY ALL OF TODAY`S MODEL SOLUTIONS NEAR THE EAST COAST OF NORTH
AMERICA WITH NEGATIVE 500-HPA HEIGHT ANOMALIES FORECAST OVER THE EASTERN CONUS.
THE ENSEMBLE SPAGHETTI DIAGRAMS INDICATE MODERATE SPREAD ACROSS THE FORECAST
DOMAIN.

BELOW NORMAL TEMPERATURES ARE FAVORED FOR MOST OF THE EASTERN OF CONUS AND THE
COASTAL PLAINS IN ASSOCIATION WITH BELOW NORMAL 500-HPA HEIGHTS. RIDGING OVER
CENTRAL NORTH AMERICA INCREASES THE CHANCES FOR ABOVE NORMAL TEMPERATURES FOR
THE WESTERN AND CENTRAL CONUS INCLUDE ALASKA, THE ALEUTIANS AND THE ALASKA
PANHANDLE.

BELOW MEDIAN PRECIPITATION IS FAVORED FOR THE CENTRAL AND EASTERN CONUS DUE TO
DESCENT EXPECTED ON THE WESTERN SIDE OF THE TROUGH FORECAST OVER THE EASTERN
U.S. AND THE WEST-CENTRAL CONUS IN ASSOCIATION WITH THE RIDGE OVER CENTRAL AND
WESTERN NORTH AMERICA.  ABOVE MEDIAN PRECIPITATION IS FAVORED FOR NEW MEXICO,
CONSISTENT WITH PRECIPITATION ESTIMATES FROM THE GFS AND ECMWF CALIBRATED
REFORECAST TOOLS. THERE ARE ENHANCED CHANCES OF BELOW MEDIAN PRECIPITATION FOR
ALASKA WEST OF A TROUGH PREDICTED OVER THE GULF OF ALASKA. THE TROUGH OVER THE
GULF OF ALASKA ENHANCES PROBABILITIES FOR ABOVE MEDIAN PRECIPITATION FOR THE
ALASKA PANHANDLE.

TODAY`S OFFICIAL 500-HPA BLEND CONSISTS OF 10% OF TODAY`S 0Z GFS ENSEMBLE MEAN
CENTERED ON DAY 8, 20% OF TODAY`S 6Z GFS ENSEMBLE MEAN CENTERED ON DAY 8, 20%
OF TODAY`S GFS SUPERENSEMBLE MEAN CENTERED ON DAY 8, 20% OF TODAY`S 0Z EUROPEAN
ENSEMBLE MEAN CENTERED ON DAY 8, 10% OF YESTERDAY`S 12Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 7, AND 20% OF TODAY`S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY
8


MODEL OF THE DAY: NO PREFERENCE

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
FAIRLY GOOD ENSEMBLE MEAN AGREEMENT.

8-14 DAY OUTLOOK FOR MAY 02 - 08 2015

TODAY`S WEEK TWO ENSEMBLE MEAN SOLUTIONS DEPICT A MEAN 500-HPA TROUGH OVER THE
GULF OF ALASKA MOVING EASTWARD COMPARED TO YESTERDAY`S PATTERN. A TROUGH IS
FORECAST OVER THE WEST COAST WITH A RIDGE OVER WESTERN CANADA AND MUCH OF THE
CENTRAL CONUS.

ABOVE NORMAL TEMPERATURE PROBABILITIES ARE ENHANCED FOR ALASKA, THE ALEUTIANS,
THE ALASKA PANHANDLE, AND MUCH OF THE CONUS IN ASSOCIATION WITH POSITIVE
500-HPA HEIGHT ANOMALIES AND THE RIDGE FORECAST OVER THE CENTRAL CONUS. WITH
THE YESTERDAY`S TROUGH OVER THE EASTERN CONUS MOVING OVER THE ATLANTIC AND THE
MEAN RIDGE MOVING EASTWARD, ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR THE GULF
COAST, ALSO INFLUENCED BY THE POSITIVE SEA SURFACE TEMPERATURE ANOMALIES.

PROBABILITIES OF BELOW MEDIAN PRECIPITATION ARE ENHANCED WEST OF THE PREDICTED
TROUGH FOR THE PARTS OF OHIO AND TENNESSEE VALLEYS, AND THE MID-ATLANTIC COAST.
ENHANCED PROBABILITIES OF ABOVE MEDIAN PRECIPITATION ARE INDICATED FOR THE
GREAT PLAINS, THE ROCKIES AND THE GREAT BASIN IN ASSOCIATION WITH A MEAN TROUGH
PREDICTED OVER THE WEST COAST. ABOVE MEDIAN PRECIPITATION IS ALSO FAVORED FOR
THE GULF COAST, CONSISTENT WITH PRECIPITATION ESTIMATES FROM THE GFS AND ECMWF
CALIBRATED REFORECAST TOOLS. THERE ARE ENHANCED PROBABILITIES OF BELOW MEDIAN
PRECIPITATION FOR EASTERN ALASKA AND THE ALASKA PANHANDLE DUE TO THE
EXPECTATION OF ABOVE NORMAL 500-HPA HEIGHTS.


THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 20% OF TODAY`S 6Z GFS ENSEMBLE
MEAN CENTERED ON DAY 11, 20% OF TODAY`S GFS SUPERENSEMBLE MEAN CENTERED ON DAY
11, 20% OF TODAY`S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 11, 20% OF
YESTERDAY`S 12Z EUROPEAN ENSEMBLE MEAN CENTERED ON DAY 10, 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
RELATIVELY GOOD AGREEMENT AMONG THE ENSEMBLE MEAN SOLUTIONS OFFSET BY LARGE
SPREAD AMONG THE COMPONENT ENSEMBLE MEMBERS OVER MUCH OF NORTH AMERICA

FORECASTER: QIN GINGER ZHANG

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:
19880419 - 20080508 - 19800508 - 20090408 - 19730428


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:
19880419 - 20080507 - 19790407 - 20090408 - 19730427


6-10 DAY OUTLOOK TABLE
OUTLOOK FOR APR 30 - MAY 04, 2015

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



8-14 DAY OUTLOOK TABLE
OUTLOOK FOR MAY 02 - 08 2015

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

$$





000
FXSA20 KWBC 241540
PMDSA

SOUTH AMERICA FORECAST DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1139 AM EDT FRI APR 24 2015

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

MODEL DISCUSSION (VALID FROM APRIL 24 AT 0000 UTC): GLOBAL MODELS
AND ENSEMBLE MEMBERS ARE IN GOOD AGREEMENT ON FORECAST EVOLUTION
OVER THE CONTINENT. SOME DISCREPANCIES ARISE OVER THE OCEANS AFTER
96 HRS. FORECAST CONFIDENCE IS HIGH OVER THE CONTINENT.

THE SUBTROPICAL RIDGE CONTINUES STRONG FOR THE TIME OF THE YEAR.
THE HIGH IS FORECAST TO CENTER IN CENTRAL SOUTH AMERICA ABOUT
10S-15S SLOWLY MEANDERING FROM SOUTHERN PARA EARLY IN THE CYCLE
WEST INTO RONDONIA BY LATE CYCLE. INITIALLY...ENHANCED VENTILATION
WILL INTERACT WITH ATLANTIC ITCZ TO ENHANCE ACTIVITY ALONG THE
NORTH COAST OF BRASIL. EXPECTING MAXIMA OF 20-45MM/DAY THROUGH
EARLY SATURDAY DECREASING AFTERWARDS. MOST OF THE STRONGEST
CONVECTION WILL EXTEND ACROSS CENTRAL TROPICAL SOUTH AMERICA AND
GRADUALLY BECOME ENHANCED ACROSS WESTERN EQUATORIAL SOUTH AMERICA.
MAXIMA WILL BE IN THE ORDER OF 20-35MM/DAY...WITH ISOLATED LARGER
AMOUNTS WEST 65W. ISOLATED DIURNAL CONVECTION IS ALSO EXPECTED IN
COASTAL ECUADOR WITH MAXIMA IN THE ORDER OF 15-25MM/DAY EARLY IN
THE CYCLE...DECREASING TO 05-10MM/DAY INTO SATURDAY/SUNDAY. AS THE
UPPER HIGH RELOCATES TO THE WEST AND INSTABILITY INCREASES
SIMULTANEOUSLY...EXPECTING AN ACTIVATION OF ANDEAN CONVECTION INTO
EARLY NEXT WEEK. THIS WILL LEAD DIURNAL MAXIMA OF 10-15MM/DAY IN
THE CENTRAL/NORTHERN PERUVIAN ANDES.

BROAD UPPER TROUGH PATTERN CONTINUES OVER THE SOUTHEASTERN PACIFIC
WHILE A RIDGE IS FORECAST TO DOMINATE THE SOUTHERN CONE. THE RIDGE
WILL MEANDER EASTWARD VERY SLOWLY. UNDER THIS PATTERN EXPECTING
TRAINS OF FRONTS TO CONSTRAIN TO EXTREME SOUTHERN CHILE WHILE
MOVING EAST-SOUTHEASTWARD. HIGHEST RAINFALL AMOUNTS ARE EXPECTED
THROUGH EARLY SATURDAY TO REACH MAXIMA OF 15-20MM/DAY ACROSS THE
AYSEN REGION IN CHILE. AMOUNTS ARE TO DECREASE AFTER. EXPECTING AN
INCREASE IN ACTIVITY ACROSS NORTHERN PATAGONIA DURING SUNDAY INTO
EARLY NEXT WEEK. HOWEVER...LIMITED MOISTURE WILL LIMIT RAINFALL
AMOUNTS. EXPECTING ALSO AN ACTIVATION OF CONVECTION IN WESTERN
PARAGUAY/NORTHWESTERN ARGENTINA AS EAST-NORTHEASTERLIES DEVELOP.
EXPECTING ISOLATED MAXIMA TO INCREASE TO 15-25MM/DAY BY SUNDAY
INTO MONDAY.

COLD FRONT OFF THE COAST OF BRASIL IS FORECAST TO MEANDER
NORTHWARD TO EXTEND INTO SOUTHERN ESPIRITO SANTO BY SATURDAY
EVENING...AND THEN STALL OVER NORTHERN ESPIRITO SANTO AFTERWARDS.
THIS FRONT IS SUSTAINING AN ILL-DEFINED SHEAR LINE INTO CENTRAL
BAHIA THROUGH EARLY SATURDAY. ALTHOUGH THE SHEAR LINE IS FORECAST
TO WEAKEN...INTERACTION OF TRADES WITH COASTAL REGIONS WILL
ENHANCE ACCUMULATIONS. EXPECTING MAXIMA OF 10-15MM/DAY THROUGH
EARLY SATURDAY INCREASING GRADUALLY TO MAXIMA OF 25-50MM/DAY
DURING SUNDAY INTO MONDAY...AIDED BY UPPER TROUGH APPROACHING FROM
THE SOUTHWEST. AMOUNTS WILL START DECREASING AFTER MONDAY.

SCHNEIDER...INMET (BRASIL)
CALLE...UNALM (PERU)
CHARPENTIER...DMC (CHILE)
DAVISON/GALVEZ...WPC (USA)
$$







000
FXUS02 KWBC 241533
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1132 AM EDT FRI APR 24 2015

VALID 12Z MON APR 27 2015 - 12Z FRI MAY 01 2015

...OVERVIEW...

THE DOMINANT FOCUS OF THE MEDIUM RANGE FCST IN TERMS OF COMBINED
SENSIBLE WEATHER IMPACTS AND UNCERTAINTY WILL BE ON THE EVOLUTION
OF CLOSED LOW ENERGY EJECTING FROM THE SRN HIGH PLAINS AND NRN
STREAM SHORTWAVES FLOWING INTO AN EASTERN CONUS MEAN TROUGH.
IMPORTANT DETAILS ARE OF THE TYPE THAT CAN BE DIFFICULT TO RESOLVE
VERY FAR IN ADVANCE BUT WILL HAVE SIGNIFICANT INFLUENCE ON
SENSIBLE WEATHER. UPSTREAM... THERE IS FAIR AGREEMENT THAT A
WESTERN CONUS MEAN RIDGE SHOULD GRADUALLY BUILD TOWARD THE PLAINS
OR AT LEAST EAST OF THE DIVIDE AS AN EPAC UPPER TROUGH DIGS SLOWLY
TOWARD THE WEST COAST. GUIDANCE SHOWS INCREASING DIVERGENCE FOR
SHORTWAVE DETAILS THAT WILL INFLUENCE TIMING/SWD EXTENT OF NWRN
CONUS PRECIP.


...GUIDANCE EVALUATION AND PREFERENCES...

ENSEMBLE AGREEMENT IS GOOD IN THE CENTRAL/EASTERN STATES THROUGH
ABOUT TUE... WITH MUCH MORE SPREAD OFF THE PAC NW COAST. FOR
WED-FRI... THE UNCERTAINTY IN FCST DETAILS INCREASES FAIRLY
RAPIDLY GIVEN THE MODEL/ENSEMBLE SPREAD IN HOW NRN PLAINS/MS VLY
ENERGY MAY INTERACT WITH THE SRN PLAINS FEATURE.  THE APPROACH OF
ONE OR MORE UPSTREAM SHRTWVS FURTHER COMPLICATES THE FCST MID-LATE
PERIOD.  THUS FAR THE GEFS/ECMWF MEANS HAVE BEEN THE MOST STABLE
GUIDANCE SOURCES OVERALL WITH THE TRACK/TIMING OF ASSOC LOW PRES
FROM THE GULF COAST INTO THE WRN ATLC... WITH ONLY TYPICAL RUN TO
RUN VARIATIONS. 00Z MODELS HAPPENED TO CLUSTER FAIRLY WELL NEAR
THE GA COAST UNTIL ABOUT LATE WED -- 00Z/30 -- BEFORE THEY
DIVERGE. 06Z GFS WENT ITS OWN WAY. 00Z GFS OFFERED THE BEST
AGREEMENT WITH THE ENSEMBLE MEANS AND OVERNIGHT CONTINUITY WHILE
THE 00Z ECMWF SHOWED ITS TYPICAL SLOWER/DEEPER BIAS... BUT WAS
WITHIN THE ENSEMBLE SPREAD. PREFERRED AN ENSEMBLE COMPROMISE
TAKING THE LOW OFF THE NC COAST AND THEN E OF SE NEW ENGLAND...
WITH ROOM TO MOVE IN ANY DIRECTION. BLOCKY PATTERN WOULD CERTAINLY
SUPPORT A SLOWER AND PERHAPS WRAPPED UP SOLUTION SO ANYTHING IS ON
THE TABLE... COMPLICATED BY NORTHERN STREAM ENERGY IN SE CANADA
THAT MAY DIVE INTO THE NORTHEAST... ALLOWING A SYSTEM TO ITS EAST
TO GET TUGGED WESTWARD.

SHRTWV DETAIL DIFFS WITHIN THE TROUGH OFF THE NWRN COAST BECOME
APPARENT ALREADY BY DAY 4/TUE. 00Z GFS RUN WAS NOTICEABLY SLOWER
THAN MOST OTHER SOLNS WITH A LEADING SHRTWV. 06Z WAS QUICKER BUT
STILL LAGGED A BIT. MODEST COMPROMISE OFFERED A GOOD STARTING
POINT. THEREAFTER... RECENT ECMWF RUNS HAVE BEEN QUICKER THAN THE
ENSEMBLES TO BRING HEIGHT FALLS INTO THE PAC NW AMID INCREASING
ENSEMBLE SPREAD. WITH GOOD AGREEMENT AMONG THE GEFS/ECENS MEMBERS
ON A SLOWER SOLUTION... OPTED TO TREND TOWARD THEM WHICH ALSO FIT
THE BILL IN THE EAST.


...SENSIBLE WEATHER HIGHLIGHTS...

HEAVY PRECIP POSSIBLE ALONG THE GULF COAST EARLY/MID-WEEK...

COMBINATION OF UPPER LOW ENERGY EJECTING FROM THE SOUTHERN
PLAINS... SFC FRONTAL BOUNDARY... AND LOW PRESSURE TRACKING ALONG
THE GULF COAST INTO THE ATLANTIC SHOULD FAVOR A LARGE AREA OF
MODEST RAIN AND SOME AREAS OF HEAVY PRECIP FROM PORTIONS OF THE
SRN HALF OF THE ROCKIES OR HIGH PLAINS THROUGH THE SOUTHEAST AND
CENTRAL/NORTHERN FLORIDA. SOME AREAS LIKELY TO BE AFFECTED HAVE
ALREADY RECEIVED SIGNIFICANT RAINFALL TOTALS OVER RECENT WEEKS.
CONSULT SPC OUTLOOKS FOR LATEST INFO REGARDING SEVERE WEATHER
THREATS... CURRENTLY INDICATED OVER THE SRN PLAINS EARLY IN THE
PERIOD.

COVERAGE AND INTENSITY OF PRECIP OVER THE CENTRAL/NORTHERN PARTS
OF THE EAST IS MUCH MORE UNCERTAIN AND DEPENDENT ON DIFFICULT TO
RESOLVE ASPECTS OF MULTIPLE FEATURES ALOFT. TEMPERATURES SHOULD
AVERAGE NEAR TO BELOW CLIMO AMID LOWER THAN AVERAGE HEIGHTS AND
NORTH/NORTHEASTERLY FLOW. MEANWHILE THE PATTERN FARTHER WWD WILL
SUPPORT MULTIPLE EPISODES OF LGT TO PERHAPS LOCALLY MDT PRECIP
OVER THE PAC NW AND VICINITY. THE MOST NOTABLE EXTREMES IN TEMPS
WILL BE FROM THE CENTRAL-SOUTHERN HIGH PLAINS INTO THE SOUTHEAST
WHERE CLOUDS/PCPN SHOULD HOLD DAYTIME HIGHS TO 5-20F BELOW AVERAGE
ONE OR MORE DAYS... AND FROM THE WEST INTO THE NORTHERN PLAINS
WHERE SOME LOCATIONS MAY SEE READINGS UP TO 10-20F ABOVE AVERAGE.


FRACASSO/RAUSCH

$$






000
FXUS02 KWBC 241533
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1132 AM EDT FRI APR 24 2015

VALID 12Z MON APR 27 2015 - 12Z FRI MAY 01 2015

...OVERVIEW...

THE DOMINANT FOCUS OF THE MEDIUM RANGE FCST IN TERMS OF COMBINED
SENSIBLE WEATHER IMPACTS AND UNCERTAINTY WILL BE ON THE EVOLUTION
OF CLOSED LOW ENERGY EJECTING FROM THE SRN HIGH PLAINS AND NRN
STREAM SHORTWAVES FLOWING INTO AN EASTERN CONUS MEAN TROUGH.
IMPORTANT DETAILS ARE OF THE TYPE THAT CAN BE DIFFICULT TO RESOLVE
VERY FAR IN ADVANCE BUT WILL HAVE SIGNIFICANT INFLUENCE ON
SENSIBLE WEATHER. UPSTREAM... THERE IS FAIR AGREEMENT THAT A
WESTERN CONUS MEAN RIDGE SHOULD GRADUALLY BUILD TOWARD THE PLAINS
OR AT LEAST EAST OF THE DIVIDE AS AN EPAC UPPER TROUGH DIGS SLOWLY
TOWARD THE WEST COAST. GUIDANCE SHOWS INCREASING DIVERGENCE FOR
SHORTWAVE DETAILS THAT WILL INFLUENCE TIMING/SWD EXTENT OF NWRN
CONUS PRECIP.


...GUIDANCE EVALUATION AND PREFERENCES...

ENSEMBLE AGREEMENT IS GOOD IN THE CENTRAL/EASTERN STATES THROUGH
ABOUT TUE... WITH MUCH MORE SPREAD OFF THE PAC NW COAST. FOR
WED-FRI... THE UNCERTAINTY IN FCST DETAILS INCREASES FAIRLY
RAPIDLY GIVEN THE MODEL/ENSEMBLE SPREAD IN HOW NRN PLAINS/MS VLY
ENERGY MAY INTERACT WITH THE SRN PLAINS FEATURE.  THE APPROACH OF
ONE OR MORE UPSTREAM SHRTWVS FURTHER COMPLICATES THE FCST MID-LATE
PERIOD.  THUS FAR THE GEFS/ECMWF MEANS HAVE BEEN THE MOST STABLE
GUIDANCE SOURCES OVERALL WITH THE TRACK/TIMING OF ASSOC LOW PRES
FROM THE GULF COAST INTO THE WRN ATLC... WITH ONLY TYPICAL RUN TO
RUN VARIATIONS. 00Z MODELS HAPPENED TO CLUSTER FAIRLY WELL NEAR
THE GA COAST UNTIL ABOUT LATE WED -- 00Z/30 -- BEFORE THEY
DIVERGE. 06Z GFS WENT ITS OWN WAY. 00Z GFS OFFERED THE BEST
AGREEMENT WITH THE ENSEMBLE MEANS AND OVERNIGHT CONTINUITY WHILE
THE 00Z ECMWF SHOWED ITS TYPICAL SLOWER/DEEPER BIAS... BUT WAS
WITHIN THE ENSEMBLE SPREAD. PREFERRED AN ENSEMBLE COMPROMISE
TAKING THE LOW OFF THE NC COAST AND THEN E OF SE NEW ENGLAND...
WITH ROOM TO MOVE IN ANY DIRECTION. BLOCKY PATTERN WOULD CERTAINLY
SUPPORT A SLOWER AND PERHAPS WRAPPED UP SOLUTION SO ANYTHING IS ON
THE TABLE... COMPLICATED BY NORTHERN STREAM ENERGY IN SE CANADA
THAT MAY DIVE INTO THE NORTHEAST... ALLOWING A SYSTEM TO ITS EAST
TO GET TUGGED WESTWARD.

SHRTWV DETAIL DIFFS WITHIN THE TROUGH OFF THE NWRN COAST BECOME
APPARENT ALREADY BY DAY 4/TUE. 00Z GFS RUN WAS NOTICEABLY SLOWER
THAN MOST OTHER SOLNS WITH A LEADING SHRTWV. 06Z WAS QUICKER BUT
STILL LAGGED A BIT. MODEST COMPROMISE OFFERED A GOOD STARTING
POINT. THEREAFTER... RECENT ECMWF RUNS HAVE BEEN QUICKER THAN THE
ENSEMBLES TO BRING HEIGHT FALLS INTO THE PAC NW AMID INCREASING
ENSEMBLE SPREAD. WITH GOOD AGREEMENT AMONG THE GEFS/ECENS MEMBERS
ON A SLOWER SOLUTION... OPTED TO TREND TOWARD THEM WHICH ALSO FIT
THE BILL IN THE EAST.


...SENSIBLE WEATHER HIGHLIGHTS...

HEAVY PRECIP POSSIBLE ALONG THE GULF COAST EARLY/MID-WEEK...

COMBINATION OF UPPER LOW ENERGY EJECTING FROM THE SOUTHERN
PLAINS... SFC FRONTAL BOUNDARY... AND LOW PRESSURE TRACKING ALONG
THE GULF COAST INTO THE ATLANTIC SHOULD FAVOR A LARGE AREA OF
MODEST RAIN AND SOME AREAS OF HEAVY PRECIP FROM PORTIONS OF THE
SRN HALF OF THE ROCKIES OR HIGH PLAINS THROUGH THE SOUTHEAST AND
CENTRAL/NORTHERN FLORIDA. SOME AREAS LIKELY TO BE AFFECTED HAVE
ALREADY RECEIVED SIGNIFICANT RAINFALL TOTALS OVER RECENT WEEKS.
CONSULT SPC OUTLOOKS FOR LATEST INFO REGARDING SEVERE WEATHER
THREATS... CURRENTLY INDICATED OVER THE SRN PLAINS EARLY IN THE
PERIOD.

COVERAGE AND INTENSITY OF PRECIP OVER THE CENTRAL/NORTHERN PARTS
OF THE EAST IS MUCH MORE UNCERTAIN AND DEPENDENT ON DIFFICULT TO
RESOLVE ASPECTS OF MULTIPLE FEATURES ALOFT. TEMPERATURES SHOULD
AVERAGE NEAR TO BELOW CLIMO AMID LOWER THAN AVERAGE HEIGHTS AND
NORTH/NORTHEASTERLY FLOW. MEANWHILE THE PATTERN FARTHER WWD WILL
SUPPORT MULTIPLE EPISODES OF LGT TO PERHAPS LOCALLY MDT PRECIP
OVER THE PAC NW AND VICINITY. THE MOST NOTABLE EXTREMES IN TEMPS
WILL BE FROM THE CENTRAL-SOUTHERN HIGH PLAINS INTO THE SOUTHEAST
WHERE CLOUDS/PCPN SHOULD HOLD DAYTIME HIGHS TO 5-20F BELOW AVERAGE
ONE OR MORE DAYS... AND FROM THE WEST INTO THE NORTHERN PLAINS
WHERE SOME LOCATIONS MAY SEE READINGS UP TO 10-20F ABOVE AVERAGE.


FRACASSO/RAUSCH

$$







000
FXCA20 KWBC 241524
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1124 AM EDT FRI APR 24 2015

DISCUSSION FROM APRIL 24/12 UTC: AT MID/UPPER LEVELS...A HIGH
AMPLITUDE TROUGH EXTENDS FROM THE WESTERN USA TO THE TROPICAL
PACIFIC. THIS TROUGH IS PRESSING AGAINST A BUILDING RIDGE TO THE
EAST...WITH THE ENSUING GRADIENT SUSTAINING A STRONG JET PATTERN
ACROSS THE NORTHERN STATES OF MEXICO. THIS CONTINUES TO FAVOR
GENERATION OF LEE SIDE PERTURBATIONS/MOUNTAIN WAVE TURBULENCE
ACROSS NORTHWEST MEXICO. FURTHERMORE...THE DEEP TROUGH PATTERN IS
ADVECTING ITCZ MOISTURE NORTHWARD ACROSS NORTHERN MEXICO INTO THE
CENTRAL USA. THROUGH SATURDAY EVENING THE TROUGH IS TO PULL OVER
THE RIDGE TO THE EAST...WITH INFLOW OF TROPICAL MOISTURE EXPECTED
TO WANE. MEANWHILE...THIS IS TO CONTINUE FEEDING ISOLATED
CONVECTION ACROSS SINALOA-CHIHUAHUA IN WESTERN MEXICO...WHILE OVER
NORTHEAST MEXICO EXPECTING SCATTERED CONVECTION TO RESULT IN
RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM.

THE SUBTROPICAL RIDGE TO THE EAST ORIGINATES ON A CLOSED 500 HPA
HIGH OVER THE YUCATAN CHANNEL. THE RIDGE EXPANDS INTO THE CENTRAL
USA WHILE ENVELOPING SOUTHERN STATES OF MEXICO-CENTRAL AMERICA AND
MOST OF THE CARIBBEAN BASIN. ALTHOUGH RIDGE TENDS TO FLATTEN OVER
THE USA...IT IS TO REMAIN STRONG AND DOMINANT ACROSS THE CARIBBEAN
BASIN-CENTRAL AMERICA...WITH AXIS TO RAPIDLY BUILD ACROSS THE
GREATER ANTILLES TO THE NORTHEAST CARIBBEAN ISLES THROUGH
SATURDAY. THE BUILDING RIDGE PATTERN IS TO SUSTAIN A TRADE WINDS
CAP ACROSS MOST OF THE BASIN. AS THE CAP STRENGTHENS...DIURNAL
CONVECTION OVER CENTRAL AMERICA IS TO CONFINE TO SOUTHERN
GUATEMALA-SOUTHERN HONDURAS/EL SALVADOR... WHERE WE EXPECT
RAINFALL AMOUNTS OF 00-05MM/DAY AND WIDELY ISOLATED MAXIMA OF
10MM. ACROSS SOUTHERN CENTRAL AMERICA... MEANWHILE...EXPECTING
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM/DAY. THIS IS TO
INCREASE TO 05-10MM/DAY AND MAXIMA OF 15-20MM THROUGH SUNDAY
MORNING. ISOLATED CONVECTION IS ALSO EXPECTED ACROSS CENTRAL
PORTIONS OF CUBA...BUT THIS IS TO DECREASE IN COVERAGE THROUGH THE
WEEKEND UNDER THE INFLUENCE OF DEVELOPING LOW-LEVEL RIDGES. ACROSS
CENTRAL HISPANIOLA...TO CLUSTER OVER THE MOUNTAINS...EXPECT
RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM.

FARTHER EAST...AT 500 HPA...BROAD TROUGH EXTENDS ACROSS THE
WESTERN NORTH ATLANTIC. THE BROAD TROUGH IS TO SLOWLY PULL TO THE
EAST NORTHEAST THROUGH FRIDAY EVENING. LATER ON
SATURDAY...HOWEVER...THE TROUGH WILL START TO LIFT AT A FASTER
PACE AS THE AFOREMENTIONED RIDGE BUILDS TO THE SOUTH. LACKING
UPPER SUPPORT...THE ASSOCIATED FRONT IS TO STALL FAR TO THE
NORTH...WITH BOUNDARY FORECAST TO BOTTOM OUT NORTH OF THE ISLANDS
BY MIDDAY TODAY. ALTHOUGH THE FRONT REMAINS FAR TO THE
NORTH...PREFRONTAL CONVECTION ACROSS THE NORTHWEST BAHAMAS IS TO
RESULT IN RAINFALL AMOUNTS OF 00-05MM/DAY
AND MAXIMA OF 10MM THROUGH SATURDAY MORNING.

ALSO AT LOW LEVELS...THE POLAR TROUGH OVER THE WESTERN ATLANTIC
SPLITS THE SUBTROPICAL RIDGE IN TWO CELLS...WITH ONE OVER THE GULF
OF MEXICO/WESTERN CARIBBEAN AND THE OTHER OVER THE CENTRAL
ATLANTIC. AN INDUCED/INVERTED TROUGH OVER THE CENTRAL CARIBBEAN
SEPARATES THESE RIDGES TO THE SOUTH. RIDGE OVER THE GULF IS TO
WEAKEN THROUGH SUNDAY MORNING...WHILE THE ONE OVER THE CENTRAL
ATLANTIC IS TO GENERALLY PERSIST. THE LATTER IS TO ACTUALLY BECOME
BETTER ORGANIZED AS THE CYCLE PROGRESSES...BUILDING INTO THE
NORTHERN GUIANAS EARLY ON SUNDAY. AS THE RIDGE BUILDS IT IS TO
DISPLACE THE ATLANTIC ITCZ SOUTH OF ITS CLIMATOLOGICAL
POSITION...TO FAVOR A DECREASE IN CONVECTION ACROSS THE GUIANAS.
EARLY IN THE CYCLE EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 15-20MM ACROSS THE NORTHERN GUIANAS...WHILE OVER THE
SOUTHERN HALF EXPECTING ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF
20-30MM. ACROSS THE GUIANAS THIS DECREASES TO 00-05MM/DAY AND
MAXIMA OF 10MM LATER ON SUNDAY...WITH MOST ACTIVE EXPECTED TO THE
SOUTH ALONG THE BORDER WITH BRASIL. OVER THE EASTERN CARIBBEAN THE
LOW LEVEL RIDGE IS TO SUSTAIN A SOUTH-SOUTHEASTERLY FLOW. THESE
ARE FORECAST TO PERSIST THROUGH DAY 05. EARLY IN THE CYCLE THIS
WILL FAVOR A SLIGHT INCREASE IN PWAT CONTENT ACROSS THE NORTHEAST
CARIBBEAN...BUT THIS WILL BE SHORT LASTING AS BUILDING MID LEVEL
RIDGE STRENGTHENS THE CAP INVERSION. LIGHT TRADE WIND SHOWERS ARE
EXPECTED OVER THE ISLAND CHAIN TO FAVOR TRACE RAINFALL AMOUNTS.

THE INDUCED/INVERTED LOW LEVEL TROUGH OVER THE CENTRAL CARIBBEAN
IS PHASING WITH THE PANAMANIAN LOW TO THE SOUTH. THIS IS ENHANCING
MOISTURE CONVERGENCE ALONG THE WEST COAST OF COLOMBIA. BUT THIS
WILL BE SHORT LASTING...WITH CONVECTION ON THE ANDEAN
REGION-SIERRA NEVADA DE SANTA MARTA TO PREVAIL OVER THE NEXT FEW
DAYS. IN THIS AREA EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY AND
MAXIMA OF 20-30MM THROUGH SATURDAY MORNING...WITH MAXIMA OF
15-20MM/DAY EXPECTED ON SATURDAY THROUGH MONDAY MORNING. ON THE
EASTERN PLAINS OF COLOMBIA AND CENTRAL VENEZUELA INITIALLY
EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM. A
SURGE IN ACTIVITY IS EXPECTED ON SATURDAY...WITH MAXIMA TO
INCREASE TO 20-45MM...BUT ON SUNDAY IT DECREASES TO RAINFALL
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15-20MM.

TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC
INITIAL  24     36     48     60     72     84     96        TYPE
NONE

CRAIG...TTMS (TRINIDAD AND TOBAGO)
SAMUEL...MDS (SURINAME)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)
$$







000
FXSA20 KWBC 241332
PMDSA

SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
931 AM EDT FRI APR 24 2015

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

SYNOPSIS (VALID FROM APRIL 24 AT 00UTC): AT 200 HPA...THE UPPER
FLOW SPLITS BETWEEN THE SUBEQUATORIAL AND SUBTROPICAL
RIDGES...WITH THE SUBEQUATORIAL RIDGE EXTENDING WEST ACROSS THE
TROPICAL ATLANTIC TO THE GUIANAS-VENEZUELA-COLOMBIA WHILE
ANCHORING ON A CLOSED HIGH NEAR 02N 37W. THE SUBTROPICAL RIDGE TO
THE SOUTH DOMINATES CONTINENTAL AREA BETWEEN 00N-30S...WHILE
CENTERING ON A CLOSED HIGH NEAR 15S 52W. DIVERGENCE BETWEEN THESE
RIDGES IS VENTING ORGANIZED DEEP CONVECTION ALONG THE NORTH COAST
OF BRASIL INTO NORTHERN PARA-AMAZONAS TO THE WEST. THE SUBTROPICAL
RIDGE IS ALSO VENTING DIURNAL CONVECTION ACROSS CENTRAL PORTIONS
OF BRASIL-NORTHERN BOLIVIA TO PERU.

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR JET FORMING AT
59S 100W ALONG 62S 84W...59S 65W...54S 54W...53S 36W...53S 15W.
THE NORTHERN POLAR JET FORMS AT 33S 105W ALONG A 144KT MAXIMA AT
39S 97W...A 146KT MAXIMA AT 46S 87W...A 173 MAXIMA AT 51S 64W...A
148KT MAXIMA AT 49S 41W...EXITING AT 43S 19W. THE SUBTROPICAL JET
FORMS AT 23S 109W ALONG 37S 94W...44S 75W...46S 56W...EXITING AT
43S 40W. ANOTHER BRANCH FORMS AT 23S 77W ALONG 28S 63W...A 129KT
MAXIMA OVER PORTO ALEGRE...28S 35W...30S 19W...35S 06W.

AT 500 HPA...A LONG WAVE TROUGH ON THE NORTHERN STREAM EXTENDS
FROM A CLOSED LOW NEAR 45S 102W...ALONG 35S 103W...TO 23S 110W.
THIS IS PRESSING AGAINST A RIDGE TO THE EAST THAT EXTENDS FROM 36S
78W... ALONG THE SOUTH COAST OF CHILE TO THE BELLINGSHAUSEN SEA.
IN A TIGHT GRADIENT BETWEEN THESE SYSTEMS...SHORT WAVE ENERGY AND
SUBTROPICAL MOISTURE FOCUSES ACROSS SOUTHERN PORTIONS OF CHILE.
FARTHER EAST... OVER THE SOUTH ATLANTIC...A BROAD/LOW AMPLITUDE
TROUGH EXTENDS BETWEEN 65W-00W AND TO THE SOUTH OF 40S. SHORT WAVE
PERTURBATIONS POPULATE THE NORTHERN STREAM FLOW ACROSS MID
SECTIONS OF SOUTH AMERICA AND THE EASTERN PACIFIC. THE WESTERNMOST
CENTERS ON A CLOSED LOW NEAR 26S 82W...WHILE TWO OTHERS TO THE
EAST EXTEND OVER CORDOBA IN ARGENTINA AND EASTERN URUGUAY/RIO
GRANDE DO SUL IN BRASIL.

THE SURFACE ANALYSIS SHOWS A 986 HPA LOW AT 50S 41W EXTENDING A
FRINT INTO 46S 55W...48S 70W...A 1002 HPA LOW AT 49S 80W...46S
81W...A 1006 HPA LOW AT 44S 89W...37S 93W. RAINFALL WAS BEING
REPORTED OVER SOUTHERN PATAGONIA. A 1003 HPA POLAR HIGH CENTERS AT
53S 78W. A 1021 HPA HIGH CENTERS AT 34S 82W. THIS HIGH RIDGES INTO
TWO 1017 HPA HIGHS. ONE CENTERS AT 29S 90W AND ANOTHER AT 40S 74W.
TO THE EAST...A 1014 HPA LOW AT 35S 09W EXTENDS A FRONT INTO 28S
18W...25S 28W...A 1014 HPA LOW AT 22S 33W...20S 38W...24S 44W...A
1014 HPA LOW AT 27S 53W...24S 56W...23S 60W. TWO THE SOUTH OF THIS
FRONT...TWO 1023 HPA HIGHS CENTER AT 30S 36W...AND AT 34S 52W.

CALLE...UNALM (PERU)
CHARPENTIER...DMC (CHILE)
SCHNEIDER...INMET (BRASIL)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)

$$







000
FXSA20 KWBC 241332
PMDSA

SOUTH AMERICA SYNOPTIC DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
931 AM EDT FRI APR 24 2015

GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

SYNOPSIS (VALID FROM APRIL 24 AT 00UTC): AT 200 HPA...THE UPPER
FLOW SPLITS BETWEEN THE SUBEQUATORIAL AND SUBTROPICAL
RIDGES...WITH THE SUBEQUATORIAL RIDGE EXTENDING WEST ACROSS THE
TROPICAL ATLANTIC TO THE GUIANAS-VENEZUELA-COLOMBIA WHILE
ANCHORING ON A CLOSED HIGH NEAR 02N 37W. THE SUBTROPICAL RIDGE TO
THE SOUTH DOMINATES CONTINENTAL AREA BETWEEN 00N-30S...WHILE
CENTERING ON A CLOSED HIGH NEAR 15S 52W. DIVERGENCE BETWEEN THESE
RIDGES IS VENTING ORGANIZED DEEP CONVECTION ALONG THE NORTH COAST
OF BRASIL INTO NORTHERN PARA-AMAZONAS TO THE WEST. THE SUBTROPICAL
RIDGE IS ALSO VENTING DIURNAL CONVECTION ACROSS CENTRAL PORTIONS
OF BRASIL-NORTHERN BOLIVIA TO PERU.

THE 250 HPA JET ANALYSIS SHOWS THE SOUTHERN POLAR JET FORMING AT
59S 100W ALONG 62S 84W...59S 65W...54S 54W...53S 36W...53S 15W.
THE NORTHERN POLAR JET FORMS AT 33S 105W ALONG A 144KT MAXIMA AT
39S 97W...A 146KT MAXIMA AT 46S 87W...A 173 MAXIMA AT 51S 64W...A
148KT MAXIMA AT 49S 41W...EXITING AT 43S 19W. THE SUBTROPICAL JET
FORMS AT 23S 109W ALONG 37S 94W...44S 75W...46S 56W...EXITING AT
43S 40W. ANOTHER BRANCH FORMS AT 23S 77W ALONG 28S 63W...A 129KT
MAXIMA OVER PORTO ALEGRE...28S 35W...30S 19W...35S 06W.

AT 500 HPA...A LONG WAVE TROUGH ON THE NORTHERN STREAM EXTENDS
FROM A CLOSED LOW NEAR 45S 102W...ALONG 35S 103W...TO 23S 110W.
THIS IS PRESSING AGAINST A RIDGE TO THE EAST THAT EXTENDS FROM 36S
78W... ALONG THE SOUTH COAST OF CHILE TO THE BELLINGSHAUSEN SEA.
IN A TIGHT GRADIENT BETWEEN THESE SYSTEMS...SHORT WAVE ENERGY AND
SUBTROPICAL MOISTURE FOCUSES ACROSS SOUTHERN PORTIONS OF CHILE.
FARTHER EAST... OVER THE SOUTH ATLANTIC...A BROAD/LOW AMPLITUDE
TROUGH EXTENDS BETWEEN 65W-00W AND TO THE SOUTH OF 40S. SHORT WAVE
PERTURBATIONS POPULATE THE NORTHERN STREAM FLOW ACROSS MID
SECTIONS OF SOUTH AMERICA AND THE EASTERN PACIFIC. THE WESTERNMOST
CENTERS ON A CLOSED LOW NEAR 26S 82W...WHILE TWO OTHERS TO THE
EAST EXTEND OVER CORDOBA IN ARGENTINA AND EASTERN URUGUAY/RIO
GRANDE DO SUL IN BRASIL.

THE SURFACE ANALYSIS SHOWS A 986 HPA LOW AT 50S 41W EXTENDING A
FRINT INTO 46S 55W...48S 70W...A 1002 HPA LOW AT 49S 80W...46S
81W...A 1006 HPA LOW AT 44S 89W...37S 93W. RAINFALL WAS BEING
REPORTED OVER SOUTHERN PATAGONIA. A 1003 HPA POLAR HIGH CENTERS AT
53S 78W. A 1021 HPA HIGH CENTERS AT 34S 82W. THIS HIGH RIDGES INTO
TWO 1017 HPA HIGHS. ONE CENTERS AT 29S 90W AND ANOTHER AT 40S 74W.
TO THE EAST...A 1014 HPA LOW AT 35S 09W EXTENDS A FRONT INTO 28S
18W...25S 28W...A 1014 HPA LOW AT 22S 33W...20S 38W...24S 44W...A
1014 HPA LOW AT 27S 53W...24S 56W...23S 60W. TWO THE SOUTH OF THIS
FRONT...TWO 1023 HPA HIGHS CENTER AT 30S 36W...AND AT 34S 52W.

CALLE...UNALM (PERU)
CHARPENTIER...DMC (CHILE)
SCHNEIDER...INMET (BRASIL)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)

$$






000
FXCA20 KWBC 241044
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
643 AM EDT FRI APR 24 2015

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM APRIL
24/06 UTC. GLOBAL MODELS AGREE ON EROSION OF AVAILABLE MOISTURE
THROUGH SUNDAY MORNING AS BUILDING MID LEVEL RIDGE STRENGTHENS ITS
FOOTHOLD ACROSS THE NORTHERN CARIBBEAN ISLANDS. AT LOW
LEVELS...RIDGE TO THE EAST IS TO FAVOR A SOUTH-SOUTHEASTERLY FLOW
THAT IS TO PERSIST FOR THE NEXT SEVERAL DAYS.

AS THE CAP INVERSION IS TO STRENGTHEN...GLOBAL MODELS ONLY SHOWING
SLIGHT RISK OF CONVECTION OVER THE NEXT TWO DAYS...WITH DRY AND
STABLE CONDITIONS TO ESTABLISH LATER ON SUNDAY. IN A PREVAILING
SOUTHERLY FLOW...HOT AND HUMID CONDITIONS ARE EXPECTED ACROSS
NORTHERN PORTIONS OF PUERTO RICO. DURING THE NOWCAST/SHORT RANGE
PERIOD...LATE AFTERNOON SHOWERS MIGHT PROVIDE SOME RELIEF ALONG
THE NORTH COAST...WITH HRWRF GUIDANCE SHOWING ACTIVITY CLUSTERING
TO THE WEST OF TOA BAJA/DORADO. ACTIVITY IS TO THEN BECOME MORE
SPARSE INTO THE MEDIUM RANGE PERIOD.

CRAIG...TTMS (TRINIDAD AND TOBAGO)
SAMUEL...MDS (SURINAME)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)
$$






000
FXCA20 KWBC 241044
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
643 AM EDT FRI APR 24 2015

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM APRIL
24/06 UTC. GLOBAL MODELS AGREE ON EROSION OF AVAILABLE MOISTURE
THROUGH SUNDAY MORNING AS BUILDING MID LEVEL RIDGE STRENGTHENS ITS
FOOTHOLD ACROSS THE NORTHERN CARIBBEAN ISLANDS. AT LOW
LEVELS...RIDGE TO THE EAST IS TO FAVOR A SOUTH-SOUTHEASTERLY FLOW
THAT IS TO PERSIST FOR THE NEXT SEVERAL DAYS.

AS THE CAP INVERSION IS TO STRENGTHEN...GLOBAL MODELS ONLY SHOWING
SLIGHT RISK OF CONVECTION OVER THE NEXT TWO DAYS...WITH DRY AND
STABLE CONDITIONS TO ESTABLISH LATER ON SUNDAY. IN A PREVAILING
SOUTHERLY FLOW...HOT AND HUMID CONDITIONS ARE EXPECTED ACROSS
NORTHERN PORTIONS OF PUERTO RICO. DURING THE NOWCAST/SHORT RANGE
PERIOD...LATE AFTERNOON SHOWERS MIGHT PROVIDE SOME RELIEF ALONG
THE NORTH COAST...WITH HRWRF GUIDANCE SHOWING ACTIVITY CLUSTERING
TO THE WEST OF TOA BAJA/DORADO. ACTIVITY IS TO THEN BECOME MORE
SPARSE INTO THE MEDIUM RANGE PERIOD.

CRAIG...TTMS (TRINIDAD AND TOBAGO)
SAMUEL...MDS (SURINAME)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)
$$







000
FXCA20 KWBC 241044
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
643 AM EDT FRI APR 24 2015

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM APRIL
24/06 UTC. GLOBAL MODELS AGREE ON EROSION OF AVAILABLE MOISTURE
THROUGH SUNDAY MORNING AS BUILDING MID LEVEL RIDGE STRENGTHENS ITS
FOOTHOLD ACROSS THE NORTHERN CARIBBEAN ISLANDS. AT LOW
LEVELS...RIDGE TO THE EAST IS TO FAVOR A SOUTH-SOUTHEASTERLY FLOW
THAT IS TO PERSIST FOR THE NEXT SEVERAL DAYS.

AS THE CAP INVERSION IS TO STRENGTHEN...GLOBAL MODELS ONLY SHOWING
SLIGHT RISK OF CONVECTION OVER THE NEXT TWO DAYS...WITH DRY AND
STABLE CONDITIONS TO ESTABLISH LATER ON SUNDAY. IN A PREVAILING
SOUTHERLY FLOW...HOT AND HUMID CONDITIONS ARE EXPECTED ACROSS
NORTHERN PORTIONS OF PUERTO RICO. DURING THE NOWCAST/SHORT RANGE
PERIOD...LATE AFTERNOON SHOWERS MIGHT PROVIDE SOME RELIEF ALONG
THE NORTH COAST...WITH HRWRF GUIDANCE SHOWING ACTIVITY CLUSTERING
TO THE WEST OF TOA BAJA/DORADO. ACTIVITY IS TO THEN BECOME MORE
SPARSE INTO THE MEDIUM RANGE PERIOD.

CRAIG...TTMS (TRINIDAD AND TOBAGO)
SAMUEL...MDS (SURINAME)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)
$$






000
FXCA20 KWBC 241044
PMDCA

TROPICAL DISCUSSION - INTERNATIONAL DESKS
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
643 AM EDT FRI APR 24 2015

PRELIMINARY DISCUSSION FOR PUERTO RICO AND THE USVI FROM APRIL
24/06 UTC. GLOBAL MODELS AGREE ON EROSION OF AVAILABLE MOISTURE
THROUGH SUNDAY MORNING AS BUILDING MID LEVEL RIDGE STRENGTHENS ITS
FOOTHOLD ACROSS THE NORTHERN CARIBBEAN ISLANDS. AT LOW
LEVELS...RIDGE TO THE EAST IS TO FAVOR A SOUTH-SOUTHEASTERLY FLOW
THAT IS TO PERSIST FOR THE NEXT SEVERAL DAYS.

AS THE CAP INVERSION IS TO STRENGTHEN...GLOBAL MODELS ONLY SHOWING
SLIGHT RISK OF CONVECTION OVER THE NEXT TWO DAYS...WITH DRY AND
STABLE CONDITIONS TO ESTABLISH LATER ON SUNDAY. IN A PREVAILING
SOUTHERLY FLOW...HOT AND HUMID CONDITIONS ARE EXPECTED ACROSS
NORTHERN PORTIONS OF PUERTO RICO. DURING THE NOWCAST/SHORT RANGE
PERIOD...LATE AFTERNOON SHOWERS MIGHT PROVIDE SOME RELIEF ALONG
THE NORTH COAST...WITH HRWRF GUIDANCE SHOWING ACTIVITY CLUSTERING
TO THE WEST OF TOA BAJA/DORADO. ACTIVITY IS TO THEN BECOME MORE
SPARSE INTO THE MEDIUM RANGE PERIOD.

CRAIG...TTMS (TRINIDAD AND TOBAGO)
SAMUEL...MDS (SURINAME)
DAVISON...WPC (USA)
GALVEZ...WPC (USA)
$$







000
FXUS01 KWBC 240836
PMDSPD

SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
436 AM EDT FRI APR 24 2015

VALID 12Z FRI APR 24 2015 - 12Z SUN APR 26 2015

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR
CENTRAL/SOUTHERN PLAINS AND THE LOWER MISSISSIPPI VALLEY...

...HEAVY RAIN POSSIBLE FOR PARTS OF THE LOWER MISSISSIPPI VALLEY
AND THE TENNESSEE VALLEY...

...TEMPERATURES WILL BE 10 TO 15 DEGREES BELOW AVERAGE OVER PARTS
OF THE NORTHEAST INTO THE MID-ATLANTIC AND OVER TO THE UPPER GREAT
LAKES...

A STORM OVER THE CENTRAL HIGH PLAINS WILL MOVE EASTWARD TO THE
MIDDLE MISSISSIPPI/WESTERN OHIO VALLEY BY SATURDAY EVENING.  A
PLUME OF MOISTURE FROM THE GULF OF MEXICO WILL STREAM NORTHWARD TO
THE PLAIN AND THE MISSISSIPPI VALLEY BY FRIDAY EVENING AND MOVE
EASTWARD TO MID-ATLANTIC BY SATURDAY EVENING.  SHOWERS AND
THUNDERSTORMS WILL DEVELOP OVER PARTS OF THE PLAINS AND
MISSISSIPPI VALLEY THAT WILL MOVE TO PART OF THE OHIO VALLEY TO
THE SOUTHEAST BY SATURDAY.  RAIN WILL DEVELOP OVER PARTS OF THE
UPPER MISSISSIPPI VALLEY/NORTHERN PLAINS AND MOVE TO THE OHIO
VALLEY BY SATURDAY MORNING MOVING TO THE MID-ATLANTIC COAST BY
SATURDAY EVENING.

MEANWHILE, A FRONT OVER THE NORTHERN ROCKIES TO THE GREAT
BASIN/NORTHERN CALIFORNIA ALONG WITH ASSOCIATED UPPER-LEVEL ENERGY
WILL MOVE EASTWARD TO THE NORTHERN HIGH PLAINS/GREAT BASIN WHILE
DISSIPATING.  UPPER-LEVEL ENERGY OVER THE PACIFIC NORTHWEST WILL
BE QUASI-STATIONARY THROUGH SATURDAY WHILE ADDITIONAL UPPER-LEVEL
ENERGY OVER THE NORTH PACIFIC WILL MOVE SOUTHEASTWARD TO SOUTHERN
CALIFORNIA BY SATURDAY EVENING.  THE STORMS WILL PRODUCE HIGHER
ELEVATION SNOW AND LOWER ELEVATION RAIN OVER PARTS OF THE PACIFIC
NORTHWEST TO THE NORTHERN ROCKIES THAT WILL EXPAND SOUTHWARD INTO
CENTRAL CALIFORNIA AND EASTWARD INTO PARTS OF THE CENTRAL ROCKIES
BY SATURDAY.  IN THE MEANTIME, SHOWERS AND THUNDERSTORMS WILL
DEVELOP OVER PARTS OF THE SOUTHERN ROCKIES/SOUTHWEST THAT WILL
EXPAND IN AREAL COVERAGE INTO PARTS OF CENTRAL ROCKIES/CENTRAL
HIGH PLAINS BY SATURDAY EVENING.  IN ADDITION, RAIN WILL DEVELOP
OVER THE NORTHERN HIGH PLAINS EARLY SATURDAY MORNING INTO SATURDAY
EVENING.

ELSEWHERE, AN UPPER-LEVEL LOW OVER NORTH NEW ENGLAND WILL SLOWLY
INCH EASTWARD OVER THE GULF OF MAINE BY SATURDAY.  THE ENERGY WILL
AID IN PRODUCING AREAS OF RAIN AND SNOW OVER PARTS OF NORTHERN NEW
ENGLAND THROUGH SATURDAY EVENING.


ZIEGENFELDER


GRAPHICS AVAILABLE AT WWW.WPC.NCEP.NOAA.GOV
$$







000
FXUS01 KWBC 240836
PMDSPD

SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
436 AM EDT FRI APR 24 2015

VALID 12Z FRI APR 24 2015 - 12Z SUN APR 26 2015

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR
CENTRAL/SOUTHERN PLAINS AND THE LOWER MISSISSIPPI VALLEY...

...HEAVY RAIN POSSIBLE FOR PARTS OF THE LOWER MISSISSIPPI VALLEY
AND THE TENNESSEE VALLEY...

...TEMPERATURES WILL BE 10 TO 15 DEGREES BELOW AVERAGE OVER PARTS
OF THE NORTHEAST INTO THE MID-ATLANTIC AND OVER TO THE UPPER GREAT
LAKES...

A STORM OVER THE CENTRAL HIGH PLAINS WILL MOVE EASTWARD TO THE
MIDDLE MISSISSIPPI/WESTERN OHIO VALLEY BY SATURDAY EVENING.  A
PLUME OF MOISTURE FROM THE GULF OF MEXICO WILL STREAM NORTHWARD TO
THE PLAIN AND THE MISSISSIPPI VALLEY BY FRIDAY EVENING AND MOVE
EASTWARD TO MID-ATLANTIC BY SATURDAY EVENING.  SHOWERS AND
THUNDERSTORMS WILL DEVELOP OVER PARTS OF THE PLAINS AND
MISSISSIPPI VALLEY THAT WILL MOVE TO PART OF THE OHIO VALLEY TO
THE SOUTHEAST BY SATURDAY.  RAIN WILL DEVELOP OVER PARTS OF THE
UPPER MISSISSIPPI VALLEY/NORTHERN PLAINS AND MOVE TO THE OHIO
VALLEY BY SATURDAY MORNING MOVING TO THE MID-ATLANTIC COAST BY
SATURDAY EVENING.

MEANWHILE, A FRONT OVER THE NORTHERN ROCKIES TO THE GREAT
BASIN/NORTHERN CALIFORNIA ALONG WITH ASSOCIATED UPPER-LEVEL ENERGY
WILL MOVE EASTWARD TO THE NORTHERN HIGH PLAINS/GREAT BASIN WHILE
DISSIPATING.  UPPER-LEVEL ENERGY OVER THE PACIFIC NORTHWEST WILL
BE QUASI-STATIONARY THROUGH SATURDAY WHILE ADDITIONAL UPPER-LEVEL
ENERGY OVER THE NORTH PACIFIC WILL MOVE SOUTHEASTWARD TO SOUTHERN
CALIFORNIA BY SATURDAY EVENING.  THE STORMS WILL PRODUCE HIGHER
ELEVATION SNOW AND LOWER ELEVATION RAIN OVER PARTS OF THE PACIFIC
NORTHWEST TO THE NORTHERN ROCKIES THAT WILL EXPAND SOUTHWARD INTO
CENTRAL CALIFORNIA AND EASTWARD INTO PARTS OF THE CENTRAL ROCKIES
BY SATURDAY.  IN THE MEANTIME, SHOWERS AND THUNDERSTORMS WILL
DEVELOP OVER PARTS OF THE SOUTHERN ROCKIES/SOUTHWEST THAT WILL
EXPAND IN AREAL COVERAGE INTO PARTS OF CENTRAL ROCKIES/CENTRAL
HIGH PLAINS BY SATURDAY EVENING.  IN ADDITION, RAIN WILL DEVELOP
OVER THE NORTHERN HIGH PLAINS EARLY SATURDAY MORNING INTO SATURDAY
EVENING.

ELSEWHERE, AN UPPER-LEVEL LOW OVER NORTH NEW ENGLAND WILL SLOWLY
INCH EASTWARD OVER THE GULF OF MAINE BY SATURDAY.  THE ENERGY WILL
AID IN PRODUCING AREAS OF RAIN AND SNOW OVER PARTS OF NORTHERN NEW
ENGLAND THROUGH SATURDAY EVENING.


ZIEGENFELDER


GRAPHICS AVAILABLE AT WWW.WPC.NCEP.NOAA.GOV
$$






000
FXUS02 KWBC 240641
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
240 AM EDT FRI APR 24 2015

VALID 12Z MON APR 27 2015 - 12Z FRI MAY 01 2015

...OVERVIEW...

THE DOMINANT FOCUS OF THE MEDIUM RANGE FCST IN TERMS OF COMBINED
SENSIBLE WEATHER IMPACTS AND UNCERTAINTY WILL BE ON THE EVOLUTION
OF CLOSED LOW ENERGY EJECTING FROM THE SRN HIGH PLAINS AND ONE OR
MORE BUNDLES OF NRN STREAM ENERGY FLOWING INTO AN ERN CONUS MEAN
TROUGH.  IMPORTANT DETAILS ARE OF THE TYPE THAT CAN BE DIFFICULT
TO RESOLVE VERY FAR IN ADVANCE BUT WILL HAVE SIGNIFICANT INFLUENCE
ON SENSIBLE WEATHER.  UPSTREAM THERE IS FAIR AGREEMENT THAT A WRN
CONUS MEAN RIDGE SHOULD GRADUALLY BUILD TOWARD THE PLAINS AS AN
ERN PAC MEAN UPR TROUGH HEADS TOWARD THE WEST COAST... THOUGH
GUIDANCE SHOWS INCREASING DIVERGENCE FOR SHRTWV DETAILS THAT WILL
INFLUENCE TIMING/SWD EXTENT OF NWRN CONUS PCPN.


...GUIDANCE EVALUATION AND PREFERENCES...

FOR CNTRL-ERN CONUS EVOLUTION THERE IS DECENT CLUSTERING INTO DAY
4 TUE.  AFTER THAT TIME THE UNCERTAINTY IN FCST DETAILS INCREASES
FAIRLY RAPIDLY GIVEN THE MODEL/ENSEMBLE SPREAD IN HOW NRN
PLAINS/MS VLY ENERGY MAY INTERACT WITH THE SRN PLAINS FEATURE.
THE APPROACH OF ONE OR MORE UPSTREAM SHRTWVS FURTHER COMPLICATES
THE FCST MID-LATE PERIOD.  THUS FAR THE GEFS/ECMWF MEANS HAVE BEEN
THE MOST STABLE GUIDANCE SOURCES OVERALL WITH THE TRACK/TIMING OF
ASSOC LOW PRES FROM THE GULF COAST INTO THE WRN ATLC... WITH ONLY
TYPICAL RUN TO RUN VARIATIONS.  AT THE MOMENT LATEST OPERATIONAL
MODELS ARE SIMILAR TO OR A LITTLE SLOWER THAN THESE MEANS AND IN
THE SLOWER PORTION OF THE VERY BROAD ENSEMBLE SPREAD FOR TIMING.
RECENT 12-HRLY GFS/ECMWF RUNS HAVE OFFERED QUITE VARIED EVOLUTIONS
SFC/ALOFT THUS PROVIDING FURTHER SUPPORT TO MAINTAINING MORE OF AN
ENSEMBLE MEAN EMPHASIS UNTIL THE MODELS STABILIZE.  LATE IN THE
PERIOD CONFIDENCE IS FAIRLY LOW IN THE PAST TWO 00Z GFS RUNS THAT
BRING CNTRL CANADA CLOSED LOW ENERGY INTO THE NORTHEAST AND AS A
RESULT PULL WRN ATLC LOW PRES TOWARD NEW ENGLAND.  THAT SAID...
SUCH AN EVOLUTION ALOFT WOULD STILL FIT WITHIN THE EXPECTED MEAN
PATTERN SO CANNOT FULLY DISCOUNT SUCH A SCENARIO.

SHRTWV DETAIL DIFFS WITHIN THE TROUGH OFF THE NWRN COAST BECOME
APPARENT ALREADY BY DAY 4 TUE.  LATEST GFS RUNS AND ESPECIALLY THE
00Z VERSION ARE NOTICEABLY SLOWER THAN MOST OTHER SOLNS WITH A
LEADING SHRTWV.  THEREAFTER THE 12Z/23 AND 00Z/23 ECMWF RUNS
BECOME PROGRESSIVE EXTREMES WITH TRAILING ENERGY... BRINGING IT
INTO THE DOWNSTREAM MEAN RIDGE MORE AGGRESSIVELY THAN OTHER MODELS
AND THE 12Z/18Z GEFS MEANS AND 12Z ECMWF/CMC MEANS.

A BLEND OF THE 18Z GFS/12Z GEFS MEAN AND 12Z ECMWF/ECMWF MEAN BEST
REPRESENTS EXISTING CONSENSUS FOR THE MON-TUE PORTION OF THE FCST.
 THEN FOR DAYS 5-7 WED-FRI PREFER A 70/30 WEIGHTING OF THE 12Z
ECMWF MEAN/GEFS MEAN.


...SENSIBLE WEATHER HIGHLIGHTS...

COMBINATION OF UPR LOW ENERGY EJECTING FROM THE SRN HIGH PLAINS
AND ASSOC LOW PRES TRACKING ALONG THE GULF COAST INTO THE ATLC
SHOULD GENERATE SOME AREAS OF HVY PCPN FROM PORTIONS OF THE SRN
HALF OF THE ROCKIES OR HIGH PLAINS THROUGH THE SRN TIER STATES.
SOME AREAS LIKELY TO BE AFFECTED HAVE ALREADY RECEIVED SIGNIFICANT
RNFL TOTALS OVER RECENT WEEKS.  CONSULT SPC OUTLOOKS FOR LATEST
INFO REGARDING SEVERE WEATHER THREATS... CURRENTLY INDICATED OVER
THE SRN PLAINS EARLY IN THE PERIOD.  COVERAGE AND INTENSITY OF
PCPN OVER THE CNTRL-NRN PARTS OF THE EAST IS MUCH MORE UNCERTAIN
AND DEPENDENT ON DIFFICULT TO RESOLVE ASPECTS OF MULTIPLE FEATURES
ALOFT.  MEANWHILE THE PATTERN FARTHER WWD WILL SUPPORT MULTIPLE
EPISODES OF LGT TO PERHAPS LOCALLY MDT PCPN OVER THE PAC NW AND
VICINITY.  THE MOST NOTABLE EXTREMES IN TEMPS WILL BE FROM THE
CNTRL-SRN HIGH PLAINS INTO THE SOUTHEAST WHERE CLOUDS/PCPN SHOULD
HOLD DAYTIME HIGHS TO 5-20F BELOW NORMAL ONE OR MORE DAYS... AND
FROM THE WEST INTO THE NRN PLAINS WHERE SOME LOCATIONS MAY SEE
READINGS UP TO 10-20F ABOVE NORMAL.

RAUSCH

$$







000
FXUS02 KWBC 240641
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
240 AM EDT FRI APR 24 2015

VALID 12Z MON APR 27 2015 - 12Z FRI MAY 01 2015

...OVERVIEW...

THE DOMINANT FOCUS OF THE MEDIUM RANGE FCST IN TERMS OF COMBINED
SENSIBLE WEATHER IMPACTS AND UNCERTAINTY WILL BE ON THE EVOLUTION
OF CLOSED LOW ENERGY EJECTING FROM THE SRN HIGH PLAINS AND ONE OR
MORE BUNDLES OF NRN STREAM ENERGY FLOWING INTO AN ERN CONUS MEAN
TROUGH.  IMPORTANT DETAILS ARE OF THE TYPE THAT CAN BE DIFFICULT
TO RESOLVE VERY FAR IN ADVANCE BUT WILL HAVE SIGNIFICANT INFLUENCE
ON SENSIBLE WEATHER.  UPSTREAM THERE IS FAIR AGREEMENT THAT A WRN
CONUS MEAN RIDGE SHOULD GRADUALLY BUILD TOWARD THE PLAINS AS AN
ERN PAC MEAN UPR TROUGH HEADS TOWARD THE WEST COAST... THOUGH
GUIDANCE SHOWS INCREASING DIVERGENCE FOR SHRTWV DETAILS THAT WILL
INFLUENCE TIMING/SWD EXTENT OF NWRN CONUS PCPN.


...GUIDANCE EVALUATION AND PREFERENCES...

FOR CNTRL-ERN CONUS EVOLUTION THERE IS DECENT CLUSTERING INTO DAY
4 TUE.  AFTER THAT TIME THE UNCERTAINTY IN FCST DETAILS INCREASES
FAIRLY RAPIDLY GIVEN THE MODEL/ENSEMBLE SPREAD IN HOW NRN
PLAINS/MS VLY ENERGY MAY INTERACT WITH THE SRN PLAINS FEATURE.
THE APPROACH OF ONE OR MORE UPSTREAM SHRTWVS FURTHER COMPLICATES
THE FCST MID-LATE PERIOD.  THUS FAR THE GEFS/ECMWF MEANS HAVE BEEN
THE MOST STABLE GUIDANCE SOURCES OVERALL WITH THE TRACK/TIMING OF
ASSOC LOW PRES FROM THE GULF COAST INTO THE WRN ATLC... WITH ONLY
TYPICAL RUN TO RUN VARIATIONS.  AT THE MOMENT LATEST OPERATIONAL
MODELS ARE SIMILAR TO OR A LITTLE SLOWER THAN THESE MEANS AND IN
THE SLOWER PORTION OF THE VERY BROAD ENSEMBLE SPREAD FOR TIMING.
RECENT 12-HRLY GFS/ECMWF RUNS HAVE OFFERED QUITE VARIED EVOLUTIONS
SFC/ALOFT THUS PROVIDING FURTHER SUPPORT TO MAINTAINING MORE OF AN
ENSEMBLE MEAN EMPHASIS UNTIL THE MODELS STABILIZE.  LATE IN THE
PERIOD CONFIDENCE IS FAIRLY LOW IN THE PAST TWO 00Z GFS RUNS THAT
BRING CNTRL CANADA CLOSED LOW ENERGY INTO THE NORTHEAST AND AS A
RESULT PULL WRN ATLC LOW PRES TOWARD NEW ENGLAND.  THAT SAID...
SUCH AN EVOLUTION ALOFT WOULD STILL FIT WITHIN THE EXPECTED MEAN
PATTERN SO CANNOT FULLY DISCOUNT SUCH A SCENARIO.

SHRTWV DETAIL DIFFS WITHIN THE TROUGH OFF THE NWRN COAST BECOME
APPARENT ALREADY BY DAY 4 TUE.  LATEST GFS RUNS AND ESPECIALLY THE
00Z VERSION ARE NOTICEABLY SLOWER THAN MOST OTHER SOLNS WITH A
LEADING SHRTWV.  THEREAFTER THE 12Z/23 AND 00Z/23 ECMWF RUNS
BECOME PROGRESSIVE EXTREMES WITH TRAILING ENERGY... BRINGING IT
INTO THE DOWNSTREAM MEAN RIDGE MORE AGGRESSIVELY THAN OTHER MODELS
AND THE 12Z/18Z GEFS MEANS AND 12Z ECMWF/CMC MEANS.

A BLEND OF THE 18Z GFS/12Z GEFS MEAN AND 12Z ECMWF/ECMWF MEAN BEST
REPRESENTS EXISTING CONSENSUS FOR THE MON-TUE PORTION OF THE FCST.
 THEN FOR DAYS 5-7 WED-FRI PREFER A 70/30 WEIGHTING OF THE 12Z
ECMWF MEAN/GEFS MEAN.


...SENSIBLE WEATHER HIGHLIGHTS...

COMBINATION OF UPR LOW ENERGY EJECTING FROM THE SRN HIGH PLAINS
AND ASSOC LOW PRES TRACKING ALONG THE GULF COAST INTO THE ATLC
SHOULD GENERATE SOME AREAS OF HVY PCPN FROM PORTIONS OF THE SRN
HALF OF THE ROCKIES OR HIGH PLAINS THROUGH THE SRN TIER STATES.
SOME AREAS LIKELY TO BE AFFECTED HAVE ALREADY RECEIVED SIGNIFICANT
RNFL TOTALS OVER RECENT WEEKS.  CONSULT SPC OUTLOOKS FOR LATEST
INFO REGARDING SEVERE WEATHER THREATS... CURRENTLY INDICATED OVER
THE SRN PLAINS EARLY IN THE PERIOD.  COVERAGE AND INTENSITY OF
PCPN OVER THE CNTRL-NRN PARTS OF THE EAST IS MUCH MORE UNCERTAIN
AND DEPENDENT ON DIFFICULT TO RESOLVE ASPECTS OF MULTIPLE FEATURES
ALOFT.  MEANWHILE THE PATTERN FARTHER WWD WILL SUPPORT MULTIPLE
EPISODES OF LGT TO PERHAPS LOCALLY MDT PCPN OVER THE PAC NW AND
VICINITY.  THE MOST NOTABLE EXTREMES IN TEMPS WILL BE FROM THE
CNTRL-SRN HIGH PLAINS INTO THE SOUTHEAST WHERE CLOUDS/PCPN SHOULD
HOLD DAYTIME HIGHS TO 5-20F BELOW NORMAL ONE OR MORE DAYS... AND
FROM THE WEST INTO THE NRN PLAINS WHERE SOME LOCATIONS MAY SEE
READINGS UP TO 10-20F ABOVE NORMAL.

RAUSCH

$$







000
FXUS02 KWBC 240641
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
240 AM EDT FRI APR 24 2015

VALID 12Z MON APR 27 2015 - 12Z FRI MAY 01 2015

...OVERVIEW...

THE DOMINANT FOCUS OF THE MEDIUM RANGE FCST IN TERMS OF COMBINED
SENSIBLE WEATHER IMPACTS AND UNCERTAINTY WILL BE ON THE EVOLUTION
OF CLOSED LOW ENERGY EJECTING FROM THE SRN HIGH PLAINS AND ONE OR
MORE BUNDLES OF NRN STREAM ENERGY FLOWING INTO AN ERN CONUS MEAN
TROUGH.  IMPORTANT DETAILS ARE OF THE TYPE THAT CAN BE DIFFICULT
TO RESOLVE VERY FAR IN ADVANCE BUT WILL HAVE SIGNIFICANT INFLUENCE
ON SENSIBLE WEATHER.  UPSTREAM THERE IS FAIR AGREEMENT THAT A WRN
CONUS MEAN RIDGE SHOULD GRADUALLY BUILD TOWARD THE PLAINS AS AN
ERN PAC MEAN UPR TROUGH HEADS TOWARD THE WEST COAST... THOUGH
GUIDANCE SHOWS INCREASING DIVERGENCE FOR SHRTWV DETAILS THAT WILL
INFLUENCE TIMING/SWD EXTENT OF NWRN CONUS PCPN.


...GUIDANCE EVALUATION AND PREFERENCES...

FOR CNTRL-ERN CONUS EVOLUTION THERE IS DECENT CLUSTERING INTO DAY
4 TUE.  AFTER THAT TIME THE UNCERTAINTY IN FCST DETAILS INCREASES
FAIRLY RAPIDLY GIVEN THE MODEL/ENSEMBLE SPREAD IN HOW NRN
PLAINS/MS VLY ENERGY MAY INTERACT WITH THE SRN PLAINS FEATURE.
THE APPROACH OF ONE OR MORE UPSTREAM SHRTWVS FURTHER COMPLICATES
THE FCST MID-LATE PERIOD.  THUS FAR THE GEFS/ECMWF MEANS HAVE BEEN
THE MOST STABLE GUIDANCE SOURCES OVERALL WITH THE TRACK/TIMING OF
ASSOC LOW PRES FROM THE GULF COAST INTO THE WRN ATLC... WITH ONLY
TYPICAL RUN TO RUN VARIATIONS.  AT THE MOMENT LATEST OPERATIONAL
MODELS ARE SIMILAR TO OR A LITTLE SLOWER THAN THESE MEANS AND IN
THE SLOWER PORTION OF THE VERY BROAD ENSEMBLE SPREAD FOR TIMING.
RECENT 12-HRLY GFS/ECMWF RUNS HAVE OFFERED QUITE VARIED EVOLUTIONS
SFC/ALOFT THUS PROVIDING FURTHER SUPPORT TO MAINTAINING MORE OF AN
ENSEMBLE MEAN EMPHASIS UNTIL THE MODELS STABILIZE.  LATE IN THE
PERIOD CONFIDENCE IS FAIRLY LOW IN THE PAST TWO 00Z GFS RUNS THAT
BRING CNTRL CANADA CLOSED LOW ENERGY INTO THE NORTHEAST AND AS A
RESULT PULL WRN ATLC LOW PRES TOWARD NEW ENGLAND.  THAT SAID...
SUCH AN EVOLUTION ALOFT WOULD STILL FIT WITHIN THE EXPECTED MEAN
PATTERN SO CANNOT FULLY DISCOUNT SUCH A SCENARIO.

SHRTWV DETAIL DIFFS WITHIN THE TROUGH OFF THE NWRN COAST BECOME
APPARENT ALREADY BY DAY 4 TUE.  LATEST GFS RUNS AND ESPECIALLY THE
00Z VERSION ARE NOTICEABLY SLOWER THAN MOST OTHER SOLNS WITH A
LEADING SHRTWV.  THEREAFTER THE 12Z/23 AND 00Z/23 ECMWF RUNS
BECOME PROGRESSIVE EXTREMES WITH TRAILING ENERGY... BRINGING IT
INTO THE DOWNSTREAM MEAN RIDGE MORE AGGRESSIVELY THAN OTHER MODELS
AND THE 12Z/18Z GEFS MEANS AND 12Z ECMWF/CMC MEANS.

A BLEND OF THE 18Z GFS/12Z GEFS MEAN AND 12Z ECMWF/ECMWF MEAN BEST
REPRESENTS EXISTING CONSENSUS FOR THE MON-TUE PORTION OF THE FCST.
 THEN FOR DAYS 5-7 WED-FRI PREFER A 70/30 WEIGHTING OF THE 12Z
ECMWF MEAN/GEFS MEAN.


...SENSIBLE WEATHER HIGHLIGHTS...

COMBINATION OF UPR LOW ENERGY EJECTING FROM THE SRN HIGH PLAINS
AND ASSOC LOW PRES TRACKING ALONG THE GULF COAST INTO THE ATLC
SHOULD GENERATE SOME AREAS OF HVY PCPN FROM PORTIONS OF THE SRN
HALF OF THE ROCKIES OR HIGH PLAINS THROUGH THE SRN TIER STATES.
SOME AREAS LIKELY TO BE AFFECTED HAVE ALREADY RECEIVED SIGNIFICANT
RNFL TOTALS OVER RECENT WEEKS.  CONSULT SPC OUTLOOKS FOR LATEST
INFO REGARDING SEVERE WEATHER THREATS... CURRENTLY INDICATED OVER
THE SRN PLAINS EARLY IN THE PERIOD.  COVERAGE AND INTENSITY OF
PCPN OVER THE CNTRL-NRN PARTS OF THE EAST IS MUCH MORE UNCERTAIN
AND DEPENDENT ON DIFFICULT TO RESOLVE ASPECTS OF MULTIPLE FEATURES
ALOFT.  MEANWHILE THE PATTERN FARTHER WWD WILL SUPPORT MULTIPLE
EPISODES OF LGT TO PERHAPS LOCALLY MDT PCPN OVER THE PAC NW AND
VICINITY.  THE MOST NOTABLE EXTREMES IN TEMPS WILL BE FROM THE
CNTRL-SRN HIGH PLAINS INTO THE SOUTHEAST WHERE CLOUDS/PCPN SHOULD
HOLD DAYTIME HIGHS TO 5-20F BELOW NORMAL ONE OR MORE DAYS... AND
FROM THE WEST INTO THE NRN PLAINS WHERE SOME LOCATIONS MAY SEE
READINGS UP TO 10-20F ABOVE NORMAL.

RAUSCH

$$






000
FXUS02 KWBC 240641
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
240 AM EDT FRI APR 24 2015

VALID 12Z MON APR 27 2015 - 12Z FRI MAY 01 2015

...OVERVIEW...

THE DOMINANT FOCUS OF THE MEDIUM RANGE FCST IN TERMS OF COMBINED
SENSIBLE WEATHER IMPACTS AND UNCERTAINTY WILL BE ON THE EVOLUTION
OF CLOSED LOW ENERGY EJECTING FROM THE SRN HIGH PLAINS AND ONE OR
MORE BUNDLES OF NRN STREAM ENERGY FLOWING INTO AN ERN CONUS MEAN
TROUGH.  IMPORTANT DETAILS ARE OF THE TYPE THAT CAN BE DIFFICULT
TO RESOLVE VERY FAR IN ADVANCE BUT WILL HAVE SIGNIFICANT INFLUENCE
ON SENSIBLE WEATHER.  UPSTREAM THERE IS FAIR AGREEMENT THAT A WRN
CONUS MEAN RIDGE SHOULD GRADUALLY BUILD TOWARD THE PLAINS AS AN
ERN PAC MEAN UPR TROUGH HEADS TOWARD THE WEST COAST... THOUGH
GUIDANCE SHOWS INCREASING DIVERGENCE FOR SHRTWV DETAILS THAT WILL
INFLUENCE TIMING/SWD EXTENT OF NWRN CONUS PCPN.


...GUIDANCE EVALUATION AND PREFERENCES...

FOR CNTRL-ERN CONUS EVOLUTION THERE IS DECENT CLUSTERING INTO DAY
4 TUE.  AFTER THAT TIME THE UNCERTAINTY IN FCST DETAILS INCREASES
FAIRLY RAPIDLY GIVEN THE MODEL/ENSEMBLE SPREAD IN HOW NRN
PLAINS/MS VLY ENERGY MAY INTERACT WITH THE SRN PLAINS FEATURE.
THE APPROACH OF ONE OR MORE UPSTREAM SHRTWVS FURTHER COMPLICATES
THE FCST MID-LATE PERIOD.  THUS FAR THE GEFS/ECMWF MEANS HAVE BEEN
THE MOST STABLE GUIDANCE SOURCES OVERALL WITH THE TRACK/TIMING OF
ASSOC LOW PRES FROM THE GULF COAST INTO THE WRN ATLC... WITH ONLY
TYPICAL RUN TO RUN VARIATIONS.  AT THE MOMENT LATEST OPERATIONAL
MODELS ARE SIMILAR TO OR A LITTLE SLOWER THAN THESE MEANS AND IN
THE SLOWER PORTION OF THE VERY BROAD ENSEMBLE SPREAD FOR TIMING.
RECENT 12-HRLY GFS/ECMWF RUNS HAVE OFFERED QUITE VARIED EVOLUTIONS
SFC/ALOFT THUS PROVIDING FURTHER SUPPORT TO MAINTAINING MORE OF AN
ENSEMBLE MEAN EMPHASIS UNTIL THE MODELS STABILIZE.  LATE IN THE
PERIOD CONFIDENCE IS FAIRLY LOW IN THE PAST TWO 00Z GFS RUNS THAT
BRING CNTRL CANADA CLOSED LOW ENERGY INTO THE NORTHEAST AND AS A
RESULT PULL WRN ATLC LOW PRES TOWARD NEW ENGLAND.  THAT SAID...
SUCH AN EVOLUTION ALOFT WOULD STILL FIT WITHIN THE EXPECTED MEAN
PATTERN SO CANNOT FULLY DISCOUNT SUCH A SCENARIO.

SHRTWV DETAIL DIFFS WITHIN THE TROUGH OFF THE NWRN COAST BECOME
APPARENT ALREADY BY DAY 4 TUE.  LATEST GFS RUNS AND ESPECIALLY THE
00Z VERSION ARE NOTICEABLY SLOWER THAN MOST OTHER SOLNS WITH A
LEADING SHRTWV.  THEREAFTER THE 12Z/23 AND 00Z/23 ECMWF RUNS
BECOME PROGRESSIVE EXTREMES WITH TRAILING ENERGY... BRINGING IT
INTO THE DOWNSTREAM MEAN RIDGE MORE AGGRESSIVELY THAN OTHER MODELS
AND THE 12Z/18Z GEFS MEANS AND 12Z ECMWF/CMC MEANS.

A BLEND OF THE 18Z GFS/12Z GEFS MEAN AND 12Z ECMWF/ECMWF MEAN BEST
REPRESENTS EXISTING CONSENSUS FOR THE MON-TUE PORTION OF THE FCST.
 THEN FOR DAYS 5-7 WED-FRI PREFER A 70/30 WEIGHTING OF THE 12Z
ECMWF MEAN/GEFS MEAN.


...SENSIBLE WEATHER HIGHLIGHTS...

COMBINATION OF UPR LOW ENERGY EJECTING FROM THE SRN HIGH PLAINS
AND ASSOC LOW PRES TRACKING ALONG THE GULF COAST INTO THE ATLC
SHOULD GENERATE SOME AREAS OF HVY PCPN FROM PORTIONS OF THE SRN
HALF OF THE ROCKIES OR HIGH PLAINS THROUGH THE SRN TIER STATES.
SOME AREAS LIKELY TO BE AFFECTED HAVE ALREADY RECEIVED SIGNIFICANT
RNFL TOTALS OVER RECENT WEEKS.  CONSULT SPC OUTLOOKS FOR LATEST
INFO REGARDING SEVERE WEATHER THREATS... CURRENTLY INDICATED OVER
THE SRN PLAINS EARLY IN THE PERIOD.  COVERAGE AND INTENSITY OF
PCPN OVER THE CNTRL-NRN PARTS OF THE EAST IS MUCH MORE UNCERTAIN
AND DEPENDENT ON DIFFICULT TO RESOLVE ASPECTS OF MULTIPLE FEATURES
ALOFT.  MEANWHILE THE PATTERN FARTHER WWD WILL SUPPORT MULTIPLE
EPISODES OF LGT TO PERHAPS LOCALLY MDT PCPN OVER THE PAC NW AND
VICINITY.  THE MOST NOTABLE EXTREMES IN TEMPS WILL BE FROM THE
CNTRL-SRN HIGH PLAINS INTO THE SOUTHEAST WHERE CLOUDS/PCPN SHOULD
HOLD DAYTIME HIGHS TO 5-20F BELOW NORMAL ONE OR MORE DAYS... AND
FROM THE WEST INTO THE NRN PLAINS WHERE SOME LOCATIONS MAY SEE
READINGS UP TO 10-20F ABOVE NORMAL.

RAUSCH

$$






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