751
FXUS06 KWBC 121934
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EDT MON AUGUST 12 2013
6-10 DAY OUTLOOK FOR AUG 18 - 22 2013
TODAYS ENSEMBLE MEAN SOLUTIONS ARE IN VERY GOOD AGREEMENT ON THE 6-10 DAY MEAN
500-HPA CIRCULATION OVER NORTH AMERICA. MODELS PREDICT ABOVE NORMAL 500-HPA
HEIGHTS OVER THE NORTHERN CONUS AND SOUTHERN CANADA, WITH NEAR TO BELOW NORMAL
HEIGHTS OVER THE SOUTHERN CONUS. A WEAK TROUGH IS FORECAST TO BE OVER THE
SOUTHEASTERN CONUS. IN SPITE OF GOOD AGREEMENT BETWEEN ENSEMBLE MEAN SOLUTIONS,
THERE IS A FAIRLY HIGH AMOUNT OF SPREAD AMONG INDIVIDUAL ENSEMBLES OF THE GEFS
AND ECMWF NEAR THE EASTERN TROUGH. THIS SUGGESTS A CONSIDERABLE AMOUNT OF
UNCERTAINTY FOR THE EASTERN CONUS, WITH THE GENERAL CONSENSUS THAT A TROUGH
WILL BE IN THE REGION, BUT CONSIDERABLE SPREAD IN THE FORECAST AMPLITUDE AND
AXIS. MODELS AGREE QUITE WELL IN THE PLACEMENT OF A FAIRLY DEEP 500-HPA TROUGH
OVER THE EASTERN NORTH PACIFIC, WELL SOUTH OF ALASKA, THAT SHOULD FOCUS A
PACIFIC STORM TRACK NEAR THE ALASKAN PANHANDLE.
THERE IS AN INCREASED CHANCE FOR ABOVE-NORMAL TEMPERATURES IN THE WESTERN CONUS
DUE TO SOUTHWESTERLY UPPER LEVEL FLOW AHEAD OF THE ANTICIPATED PACIFIC TROUGH.
A WEAK RIDGE EXPECTED OVER ROCKIES AND GENERAL ABOVE NORMAL 500-HPA HEIGHTS
OVER SOUTHERN CANADA EXTEND THE AREA OF ENHANCED ODDS OF ABOVE-NORMAL
TEMPERATURES ALONG THE NORTHERN CONUS TO NEW ENGLAND. NEAR THE ANTICIPATED
TROUGH, BELOW-NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF THE SOUTH CENTRAL AND
SOUTHEASTERN CONUS. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF ALASKA
DUE TO INDICATIONS FROM LOW LEVEL TEMPERATURES FROM THE GEFS AND CANADIAN
MODELS.
INCREASED ODDS FOR ABOVE-MEDIAN PRECIPITATION ARE FORECAST ACROSS THE
SOUTHEASTERN CONUS NEAR THE EXPECTED TROUGH. THE NORTHERN AND WESTERN EDGE OF
THIS AREA WILL DEPEND ON THE EXACT ORIENTATION OF THE EASTERN TROUGH, AND IS
QUITE UNCERTAIN AT THIS TIME. THE PACIFIC JET IS EXPECTED TO BE FOCUSED ON THE
ALASKAN PANHANDLE, EAST OF THE NORTH PACIFIC TROUGH, RESULTING IN A NORTHWARD
SHIFT IN THE STORM TRACK OVER WESTERN NORTH AMERICA, AND INCREASING CHANCES FOR
BELOW-MEDIAN PRECIPITATION FOR MUCH OF THE WESTERN CONUS AND NORTHERN GREAT
PLAINS. THE EXPECTED PACIFIC JET INCREASES CHANCES FOR ABOVE-MEDIAN
PRECIPITATION FOR EASTERN ALASKA INCLUDING THE PANHANDLE. MOST TOOLS FAVOR
BELOW MEDIAN PRECIPITATION FOR WESTERN ALASKA.
TODAY'S OFFICIAL 500-HPA BLEND CONSISTS OF 40 PERCENT OF TODAY'S 6Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8...10 PERCENT OF TODAY'S OPERATIONAL 0Z ECMWF
CENTERED ON DAY 8...30 PERCENT OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN CENTERED ON
DAY 8...AND 20 PERCENT OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY 8.
MODEL OF THE DAY: TODAYS 06Z GFS ENSEMBLE MEAN.
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: BELOW AVERAGE, 2 OUT OF 5, DUE TO
RELATIVELY WEAK ANOMALY MAGNITUDES OVER MUCH OF THE CONUS, AND CONSIDERABLE
DIFFERENCES IN MODEL SOLUTIONS NEAR THE TROUGH ANTICIPATED OVER THE EASTERN
CONUS.
8-14 DAY OUTLOOK FOR AUG 20 - 26 2013
THE FORECAST PATTERN IN THE 500-HPA MANUAL BLEND FOR WEEK 2 IS QUITE SIMILAR TO
THE 6-10 DAY PERIOD. THE FAIRLY DEEP TROUGH OVER THE NORTH PACIFIC FORECAST
DURING THE 6-10 DAY PERIOD IS MUCH WEAKER IN THE 8-14 DAY MEAN AND APPEARS TO
HAVE RETROGRADED TO A POSITION OVER THE ALEUTIANS. OTHERWISE THE EXPECTED
CIRCULATION IS LARGELY UNCHANGED BETWEEN THE TWO PERIODS. JUST AS IN THE
FORECAST FOR THE 6-10 DAY PERIOD, THE ENSEMBLE MEAN SOLUTIONS ARE IN GOOD
AGREEMENT, BUT INDIVIDUAL MEMBERS OF THE GEFS, ECMWF AND CANADIAN MODELS
INDICATE A HIGH SPREAD OF SOLUTIONS.
THE TEMPERATURE OUTLOOK FOR THE 8-14 DAY PERIOD IS VERY SIMILAR TO THE 6-10 DAY
OUTLOOK. THE PRECIPITATION OUTLOOK IS ALSO SIMILAR, EXCEPT FOR PORTIONS OF THE
SOUTHERN GREAT PLAINS, WHERE THE GEFS REFORECAST TOOL SUGGESTS AN INCREASED
CHANCE FOR ABOVE-MEDIAN PRECIPITATION AMOUNTS. THE CONTINUED FORECAST OF A
TROUGH OVER THE EASTERN PART OF THE CONUS INCREASES THE CHANCES OF ABOVE-MEDIAN
PRECIPITATION OVER PARTS OF THE NORTHEAST AS WELL.
THE OFFICIAL 8-14 DAY HEIGHT PROG CONSISTS OF: 10 PERCENT OF TODAY'S
OPERATIONAL 6Z GFS CENTERED ON DAY 11...40 PERCENT OF TODAY'S 6Z GFS ENSEMBLE
MEAN CENTERED ON DAY 11...30 PERCENT OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11...AND 20 PERCENT OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN
CENTERED ON DAY 11.
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: NEAR AVERAGE, 3 OUT OF 5, DUE
TO RELATIVELY GOOD AGREEMENT IN ENSEMBLE MEANS, BUT RELATIVELY HIGH SPREAD
AMONG INDIVIDUAL MEMBERS.
FORECASTER: DAVE UNGER
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
AUGUST 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:
19740731 - 19790812 - 19990806 - 19540811 - 19750817
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:
19990805 - 19540812 - 19800810 - 19740730 - 19530804
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 18 - 22 2013
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A N
SRN CALIF A N IDAHO A B NEVADA A B
W MONTANA A B E MONTANA A B WYOMING A B
UTAH A B ARIZONA A N COLORADO N B
NEW MEXICO A B N DAKOTA A B S DAKOTA A B
NEBRASKA N B KANSAS B N OKLAHOMA B N
N TEXAS B N S TEXAS N N W TEXAS N N
MINNESOTA A N IOWA N B MISSOURI B N
ARKANSAS B A LOUISIANA B A WISCONSIN A N
ILLINOIS N N MISSISSIPPI B A MICHIGAN A N
INDIANA N N OHIO N N KENTUCKY N A
TENNESSEE B A ALABAMA B A NEW YORK A N
VERMONT A B NEW HAMP A B MAINE A B
MASS A B CONN A B RHODE IS A B
PENN A N NEW JERSEY A N W VIRGINIA N A
MARYLAND A A DELAWARE A A VIRGINIA N A
N CAROLINA N A S CAROLINA B A GEORGIA B A
FL PNHDL B A FL PENIN A A AK N SLOPE N B
AK ALEUTIAN N B AK WESTERN A B AK INT BSN A A
AK S INT A N AK SO COAST N A AK PNHDL N A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR AUG 20 - 26 2013
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A B
SRN CALIF A N IDAHO A B NEVADA A B
W MONTANA A B E MONTANA A B WYOMING A N
UTAH A N ARIZONA A N COLORADO A N
NEW MEXICO A N N DAKOTA A B S DAKOTA A N
NEBRASKA N N KANSAS B A OKLAHOMA B A
N TEXAS N A S TEXAS A N W TEXAS A N
MINNESOTA A B IOWA N N MISSOURI B N
ARKANSAS B A LOUISIANA N A WISCONSIN A N
ILLINOIS N N MISSISSIPPI B A MICHIGAN A N
INDIANA N N OHIO N N KENTUCKY B N
TENNESSEE B A ALABAMA B A NEW YORK A A
VERMONT A A NEW HAMP A A MAINE A N
MASS A A CONN A A RHODE IS A A
PENN A A NEW JERSEY A A W VIRGINIA N A
MARYLAND A A DELAWARE N A VIRGINIA N A
N CAROLINA N A S CAROLINA N A GEORGIA N A
FL PNHDL N A FL PENIN A N AK N SLOPE N B
AK ALEUTIAN A A AK WESTERN A N AK INT BSN A N
AK S INT A A AK SO COAST A A AK PNHDL N A
LEGEND
TEMPS WITH RESPECT TO NORMAL PCPN WITH RESPECT TO MEDIAN
A - ABOVE N - NEAR NORMAL A - ABOVE N - NEAR MEDIAN
B - BELOW B - BELOW
THE FORECAST CLASSES REPRESENT AVERAGES FOR EACH STATE. NORMAL
VALUES - WHICH MAY VARY WIDELY ACROSS SOME STATES - ARE
AVAILABLE FROM YOUR LOCAL WEATHER SERVICE FORECAST OFFICE.
FOR ADDITIONAL INFORMATION SEE MESSAGE FXUS06 KWBC - ON AWIPS AS
PMDMRD.
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