PROGNOSTIC DISCUSSIONS FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EDT TUE MAY 04 2004
6 TO 10 DAY OUTLOOK FOR MAY 10 - 14 2004
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TODAYS MODEL HEIGHT GUIDANCE SHOWS FAIRLY GOOD SIMILARITY OF EXPEC-
TED CIRCULATION FEATURES OVER THE NORTH AMERICAN VICINITY FOR THE
6-10 DAY PERIOD...THOUGH THERE ARE SOME MINOR DIFFERENCES CONCERNING
THE AMPLITUDE OF VARIOUS LONGWAVES.  THE OPERATIONAL ECMWF HAS CON-
SIDERABLE AMPLITUDE IN THE NORTH AMERICAN WAVE FEATURES...WHICH IS
FAIRLY COMMON WITH THIS MODEL.  AN OVERALL CONSENSUS OF MODEL RUNS
INDICATES GOOD SIMILARITY WITH YESTERDAYS OFFICIAL 500-HPA BLEND
MAP.  THE PROMINENT CIRCULATION FEATURES INCLUDE A STRONG ANOMALOUS
RIDGE OVER THE GULF OF ALASKA - A DOWNSTREAM TROUGH NEAR THE WEST
COAST OF THE UNITED STATES - A FAIRLY FLAT RIDGE OVER THE SOUTHEAST
- AND A BELT OF NEAR TO BELOW AVERAGE HEIGHTS FROM NORTHERN ALASKA
EASTWARD ACROSS MOST OF CANADA TO THE GRAND BANKS/NEWFOUNDLAND AREA.
IN ADDITION...SIGNIFICANTLY ABOVE AVERAGE HEIGHTS DOMINATE MOST OF
THE POLAR BASIN WITH AN ANOMALOUS BLOCK PERCHED OVER GREENLAND.
THE BLEND COMPOSITE ANALOG - WHICH SIMPLY COMPOSITES THE 10 BEST
HISTORICAL HEIGHT MATCHES TO TODAYS BLEND PATTERN - SHOWS A CORREL-
ATION OF 0.89 WITH TODAYS BLEND...WHICH IS QUITE USEFUL.  INSPEC-
TION OF THE D+8 NCEP ENSEMBLE SPAGHETTI MAPS SHOWS THE 5760M CON-
TOURS IN REASONABLY GOOD AGREEMENT ACROSS THE SOUTHERN U.S. WITH
A WESTERN TROUGH/EASTERN RIDGE...BUT THE NORTHERN STREAM (5520M)
CONTOURS SHOW MUCH UNCERTAINTY/SPREAD NEAR AND NORTH OF THE CANA-
DIAN BORDER.  ANOTHER ITEM OF INTEREST INVOLVES THE POSSIBILITY
OF FREQUENT SHORTWAVES ROUNDING THE BASE OF THE WESTERN TROUGH
AND MOVING INTO THE GREAT PLAINS.  THIS WILL ELEVATE THE LIKELI-
HOOD OF STRONG AND SEVERE THUNDERSTORMS ACROSS THE PLAINS REGION
...BUT SPECIFIC DETAILS OF PARAMETERS SUCH AS LOW LEVEL MOISTURE -
INSTABILITY - AND WIND SHEAR PROFILES - REMAIN ELUSIVE THIS FAR
IN ADVANCE.
THE OFFICIAL HEIGHT PROG FOR TODAY CONSISTS OF 50 PERCENT OF THE
ECMWF ENSEMBLE MEAN CENTERED ON DAY 7... 20 PERCENT OF THE LATEST
CANADIAN ENSEMBLE CENTERED ON DAY 8...10 PERCENT OF TODAYS 0Z GFS
OPERATIONAL RUN CENTERED ON DAY 8...AND 20 PERCENT OF THE GFS
ENSEMBLE RUN CENTERED ON DAY 8.
MODEL OF THE DAY: ECMWF ENSEMBLE
FORECAST CONFIDENCE FOR THE 6 TO 10 DAY PERIOD IS JUDGED TO BE
ABOVE AVERAGE TODAY...4 ON A SCALE FROM 1 TO 5...MAINLY DUE TO
FAIRLY GOOD AGREEMENT AND CONTINUITY BETWEEN MOST MODEL RUNS.
THE 6 TO 10 DAY TEMPERATURE PROG IS BASED ON THE ANALOG COMPOSITE
TO THE 500-HPA BLEND AS WELL AS THE KLEIN AND NEURAL NET SPECIFI-
CATIONS FROM THE OFFICIAL 500-HPA BLEND.  IT IS ALSO BASED ON A
SUBJECTIVE INTERPRETATION OF THE 6Z GFS DAILY PROGS OF THICKNESS
ADVECTION (1000 TO 500 HPA) PATTERNS....AND ON CDC REFORECAST
TEMPERATURES.
THE 6 TO 10 DAY PRECIPITATION PROG IS BASED ON CALIBRATED GFS OUT-
PUT... ANALOGS AND NEURAL NETWORK SPECIFICATIONS TO THE 500-HPA
BLEND.  IT IS ALSO BASED ON A SUBJECTIVE INTERPRETATION OF THE 6Z
GFS DAILY PROGS OF RAINFALL PATTERNS AND MEAN STORM TRACKS...AND
ON CDC PRECIPITATION.
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8 TO 14 DAY OUTLOOK FOR MAY 12 - 18 2004
THE WEEK 2 CIRCULATION MODELS INDICATE ONLY SMALL CHANGES RELATIVE
TO THE EXPECTED 6-10 DAY CIRCULATION.  THE EASTERN U.S. RIDGE GETS
PRESSED SOMEWHAT TO THE SOUTH...AS WELL AS THE GULF OF ALASKA
RIDGE.  THE CHANCES FOR WIDESPREAD SEVERE WEATHER ARE ENHANCED
OVER THE GREAT PLAINS REGION AS THE WESTERN U.S. TROUGH CONTINUES
TO PUSH EASTWARD...AND THE MONTH OF MAY IS PRIME TIME FOR THE
DEVELOPMENT OF SEVERE STORMS OVER THE CENTRAL STATES.
THE OFFICIAL HEIGHT PROG FOR TODAY CONSISTS OF 35 PERCENT OF THE
GFS ENSEMBLE MEAN CENTERED ON DAY 11... 30 PERCENT OF TODAYS 0Z
GFS CENTERED ON DAY 11...AND 35 PERCENT OF TODAYS 6Z GFS CENTERED
ON DAY 11.  THE GFS ENSEMBLE CONTINUES TO SHOW SIGNIFICANT SPREAD
AMONG ITS MEMBERS...AND THE ENSEMBLE MEAN AGAIN FORECASTS A WEAK
OVERALL HEIGHT ANOMALY PATTERN ACROSS THE LOWER 48.
FORECAST CONFIDENCE FOR THE 8 TO 14 DAY PERIOD IS JUDGED TO BE
NEAR AVERAGE TODAY... 3 ON A SCALE OF 1 TO 5.
THE 8 TO 14 DAY TEMPERATURE PROG IS BASED ON KLEIN AND NEURAL NET
SPECIFICATIONS... AS WELL AS ANALOGS...FROM THE BLEND - CDC
REFORECAST TEMPERATURES - AND TO SOME DEGREE ON THE EXPECTED
EXTRAPOLATION OF THE 6-10 DAY CIRCULATION PATTERN.
THE 8 TO 14 DAY PRECIPITATION PROG IS BASED ON ANALOGS TO THE 500
HPA BLEND... THE CALIBRATED GFS OUTPUT... TO SOME DEGREE ON THE
EXPECTED EXTRAPOLATION OF THE 6-10 DAY FORECAST RAINFALL...AND ON
CDC PRECIPITATION.
FORECASTER: A. ARTUSA
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NOTES:
AUTOMATED FORECASTS ARE ISSUED ON SATURDAY AND SUNDAY.  OTHERWISE -
FORECASTS INCORPORATE FORECASTER INPUT.
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
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 NARRATIVE DESCRIPTION OF THE FORECAST PATTERNS FOR TEMPERATURE
AND PRECIPITATION FOR BOTH THE 6-10 OR 8-14 DAY PERIODS HAS BEEN
DISCONTINUED.  THE STATE TABLES FOR BOTH THE 6-10 AND 8-14 DAY
PERIODS ARE NOW CONTAINED IN THIS MESSAGE...AVAILABLE AS PMDMRD ON
AWIPS.
EFFECTIVE THURSDAY MAY 17 2001...THE CLIMATE PREDICTION CENTER
HAS SWITCHED TO 1971-2000 BASE PERIOD MEANS FOR TEMPERATURE...
PRECIPITATION...AND 500-HPA HEIGHTS AS REFERENCE IN THE CLIMATE
OUTLOOKS.  THE 1971-2000 BASE PERIOD MEANS HAVE REPLACED THE
1961-1990 BASE PERIOD MEANS.
THE NEXT MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED THURSDAY
MAY 20TH.
NEW NOTE EFFECTIVE MAR 16 2004:
THE GLOSSARY FORMERLY FOUND AT THIS LOCATION WILL NO LONGER BE
TRANSMITTED AS PART OF THIS MESSAGE. IF YOU WISH TO SEE THE
DEFINITIONS OF TERMS USED IN THESE MESSAGES... PLEASE GO TO THE
CPC WEB PAGE AT (USE LOWER CASE) HTTP://WWW.CPC.NCEP.NOAA.GOV
AND FOLLOW THE APPROPRIATE LINKS.
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:
19810510 - 19900502 - 19690518 - 19900414 - 19810507
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:
19890414 - 19900502 - 19580430 - 19900413 - 19900416
6 to 10 day Outlook Table
OUTLOOK FOR MAY 10 - 14, 2004
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  B    N     OREGON      B    A     NRN CALIF   B    A
SRN CALIF   B    B     IDAHO       B    N     NEVADA      N    B
W MONTANA   B    N     E MONTANA   N    A     WYOMING     N    A
UTAH        N    B     ARIZONA     N    B     COLORADO    N    N
NEW MEXICO  N    B     N DAKOTA    N    A     S DAKOTA    N    A
NEBRASKA    N    A     KANSAS      N    N     OKLAHOMA    A    N
N TEXAS     A    B     S TEXAS     A    B     W TEXAS     N    B
MINNESOTA   N    A     IOWA        N    A     MISSOURI    A    N
ARKANSAS    A    B     LOUISIANA   A    B     WISCONSIN   N    A
ILLINOIS    A    N     MISSISSIPPI A    B     MICHIGAN    N    A
INDIANA     A    A     OHIO        A    A     KENTUCKY    A    N
TENNESSEE   A    B     ALABAMA     A    B     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        A    N     NEW JERSEY  A    N     W VIRGINIA  A    N
MARYLAND    A    N     DELAWARE    A    N     VIRGINIA    A    N
N CAROLINA  A    B     S CAROLINA  A    B     GEORGIA     A    B
FL PNHDL    A    B     FL PENIN    N    N     AK N SLOPE  N    B
AK ALEUTIAN A    A     AK WESTERN  N    A     AK INT BSN  N    B
AK S INT    N    N     AK SO COAST N    N     AK PNHDL    N    N
8 to 14 day Outlook Table
OUTLOOK FOR MAY 12 - 18, 2004
STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  N    N     OREGON      B    N     NRN CALIF   B    A
SRN CALIF   B    B     IDAHO       B    A     NEVADA      N    A
W MONTANA   B    A     E MONTANA   B    A     WYOMING     B    A
UTAH        N    B     ARIZONA     N    B     COLORADO    N    N
NEW MEXICO  N    B     N DAKOTA    B    N     S DAKOTA    B    N
NEBRASKA    N    N     KANSAS      N    A     OKLAHOMA    A    A
N TEXAS     A    N     S TEXAS     A    B     W TEXAS     A    N
MINNESOTA   N    N     IOWA        N    A     MISSOURI    N    A
ARKANSAS    A    N     LOUISIANA   A    B     WISCONSIN   N    N
ILLINOIS    N    A     MISSISSIPPI A    B     MICHIGAN    N    A
INDIANA     N    A     OHIO        N    A     KENTUCKY    N    A
TENNESSEE   A    N     ALABAMA     A    B     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    N     NEW JERSEY  N    N     W VIRGINIA  A    N
MARYLAND    A    N     DELAWARE    A    N     VIRGINIA    A    N
N CAROLINA  A    B     S CAROLINA  A    B     GEORGIA     A    B
FL PNHDL    A    B     FL PENIN    A    B     AK N SLOPE  N    N
AK ALEUTIAN A    A     AK WESTERN  N    N     AK INT BSN  N    N
AK S INT    N    A     AK SO COAST N    A     AK PNHDL    N    N
                           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.
$$