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FXUS06 KWBC 152016
PMDMRD
PROGNOSTIC DISCUSSION FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK, MD
300 PM EST FRI DECEMBER 15 2023
6-10 DAY OUTLOOK FOR DEC 21 - 25 2023
THE FORECASTED MID-LEVEL HEIGHT PATTERN CONTINUES TO LOOK SIMILAR TO PREVIOUS
FORECASTS. POSITIVE 500-HPA HEIGHT ANOMALIES ARE FORECAST ACROSS MUCH OF THE
CONTIGUOUS U.S. (CONUS) CENTERED ACROSS THE UPPER GREAT LAKES REGION. A
DEPARTING SHORTWAVE TROUGH AND ACCOMPANYING WEAK NEGATIVE 500-HPA HEIGHT
ANOMALIES ARE DEPICTED WELL EAST OF FLORIDA. THE MANUAL HEIGHT BLEND DEPICTS
ANOTHER SHORTWAVE TROUGH WITH SLIGHTER LARGER NEGATIVE 500-HPA HEIGHT ANOMALIES
NEAR THE SOUTHERN CALIFORNIA COAST. UNCALIBRATED GEFS, ECMWF, AND CANADIAN
ENSEMBLE MEANS INITIALLY PREDICT THIS SYSTEM TO BE CUT-OFF, THOUGH IT’S
PREDICTED TO BECOME AN OPEN-WAVE TROUGH BY THE MIDDLE OF THE 6-10 DAY PERIOD. A
MUCH MORE SIGNIFICANT MID-LEVEL TROUGH IS FORECAST TO AMPLIFY ACROSS THE
EASTERN PACIFIC DURING THE MIDDLE AND LATTER PORTIONS OF THE 6-10 DAY PERIOD,
EXTENDING BACK OVER SOUTHWESTERN ALASKA AND THE EASTERN BERING SEA. AHEAD OF
THIS DEEP TROUGH, MOIST SOUTHERLY FLOW IS EXPECTED ACROSS EASTERN ALASKA. IN
HAWAII, NEAR TO SLIGHTLY ABOVE-NORMAL 500-HPA HEIGHTS ARE FAVORED.
THE PERSISTENT PACIFIC FLOW ACROSS THE CONUS LEADS TO A CONTINUATION OF MILD
TEMPERATURES FOR MUCH OF THE CONUS. THE LARGEST PROBABILITIES, MORE THAN 90%,
FOR ABOVE-NORMAL TEMPERATURES ARE FORECAST ACROSS THE UPPER MISSISSIPPI VALLEY,
WITH THE GEFS FORECASTING 2-METER AVERAGE TEMPERATURES AT LEAST 15 DEGREES
ABOVE NORMAL FOR THE 6-10 DAY PERIOD. NEAR-NORMAL TEMPERATURES ARE FAVORED FOR
FLORIDA AND ADJACENT PARTS OF THE SOUTHEAST COAST, IN THE WAKE OF THE SOUTHERN
STREAM SYSTEM WELL EAST OF FLORIDA. ABOVE-NORMAL TEMPERATURES ARE FAVORED
ACROSS EASTERN ALASKA AS SOUTHERLY FLOW CONTINUES TO BRING WARM MOIST AIR FROM
THE PACIFIC INTO THE REGION WHILE NEAR- TO BELOW-NORMAL TEMPERATURES ARE
FAVORED ACROSS CENTRAL AND WESTERN ALASKA, CLOSER TO THE TROUGH AXIS. IN
HAWAII, ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR THE ENTIRE ARCHIPELAGO, BASED
ON THE TEMPERATURE CONSOLIDATION TOOL.
ABOVE-NORMAL PRECIPITATION IS FAVORED FROM CALIFORNIA EAST TO MOST OF THE GREAT
PLAINS AND MISSISSIPPI VALLEY, LOWER OHIO AND TENNESSEE VALLEYS, AND GULF COAST
REGION AS MOIST AIR FROM THE PACIFIC CONTINUES TO FLOW INTO THE WESTERN CONUS.
PROBABILITIES FAVORING ABOVE-NORMAL PRECIPITATION EXCEED 60% FROM SOUTHERN
CALIFORNIA EASTWARD TO THE SOUTHERN HIGH PLAINS. THIS IS BASED ON GOOD
AGREEMENT BETWEEN THE CONSOLIDATED AND AUTOMATED TEMPERATURE TOOLS DURING THE 6
TO 10 DAY PERIOD. BELOW-NORMAL PRECIPITATION CHANCES ARE ENHANCED OVER THE
NORTHWESTERN CONUS, FROM THE PACIFIC NORTHWEST EASTWARD TO THE DAKOTAS, WELL
REMOVED FROM THE PRIMARY STORM TRACK. BELOW-NORMAL PRECIPITATION CHANCES ARE
ALSO INCREASED EAST OF A LINE THAT EXTENDS FROM ABOUT MICHIGAN TO SOUTH
CAROLINA, CONSISTENT WITH CONSOLIDATED AND AUTOMATED PRECIPITATION TOOLS. IN
ALASKA, ABOVE-NORMAL PRECIPITATION IS FAVORED FOR MOST OF THE STATE AS
SOUTHERLY FLOW AROUND A MID-LEVEL TROUGH AND SURFACE LOW-PRESSURE BRING
INCREASED MOISTURE INTO THE STATE. ODDS FAVORING ABOVE-NORMAL PRECIPITATION
EXCEED 50% OVER PARTS OF SOUTH-CENTRAL AND SOUTHEAST ALASKA. ACROSS THE
HAWAIIAN ISLANDS, ABOVE-NORMAL PRECIPITATION IS FAVORED DUE TO A PREDICTED FLOW
OF DEEP TROPICAL MOISTURE AHEAD OF AN APPROACHING MID-LEVEL TROUGH.
THE OFFICIAL 6-10 DAY 500-HPA HEIGHT BLEND CONSISTS OF 33% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 8, 34% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 8, AND 33% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON DAY
8
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO
GOOD AGREEMENT AMONG THE MID-LEVEL HEIGHT FORECASTS, OFFSET BY MINOR
DIFFERENCES AMONG THE SURFACE TEMPERATURE AND PRECIPITATION TOOLS.
8-14 DAY OUTLOOK FOR DEC 23 - 29 2023
AS WITH THE 6 TO 10 DAY PERIOD, THE FORECASTED 500-HPA HEIGHT PATTERN REMAINS
IN GOOD AGREEMENT WITH THE EARLIER PERIOD AND YESTERDAY’S FORECAST. POSITIVE
500-HPA HEIGHT ANOMALIES CONTINUE OVER ALL BUT FAR WESTERN AND SOUTHERN
PORTIONS OF THE CONUS WITH THE PATTERN PROGRESSING NORTHEASTWARD RELATIVE TO
YESTERDAY. NEAR- TO SLIGHTLY BELOW-NORMAL 500-HPA HEIGHTS ARE FAVORED ACROSS
THE FAR WEST DUE TO A NEARBY MID-LEVEL TROUGH, AND ACROSS APPROXIMATELY THE
SOUTHERN ONE-THIRD TO ONE-HALF OF THE CONUS AS THE LARGE ANOMALOUS RIDGE PULLS
AWAY FROM THIS REGION TO THE NORTHEAST. NEGATIVE 500-HPA HEIGHT ANOMALIES ARE
FORECAST OVER THE GULF OF ALASKA AND EASTERN PACIFIC, WITH SHORTER-WAVELENGTH
ENERGY EXPECTED TO MOVE ONSHORE INTO THE WESTERN CONUS. POSITIVE 500-HPA HEIGHT
ANOMALIES ARE FORECAST ACROSS THE HAWAIIAN ISLANDS.
ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR NEARLY THE ENTIRE CONUS FOR THE
WEEK-2 PERIOD. THE GREATEST CHANCES FOR ABOVE-NORMAL TEMPERATURES, EXCEEDING
80%, IS OVER THE DAKOTAS AND MINNESOTA. THIS IS WELL SUPPORTED BY THE
REFORECAST TEMPERATURE TOOLS AND THE STATISTICAL ANALOGS FROM THE MANUAL HEIGHT
BLEND. NEAR-NORMAL TEMPERATURES ARE FAVORED OVER THE FLORIDA PENINSULA,
CONSISTENT WITH PREDICTED NEAR- TO BELOW-NORMAL 500-HPA HEIGHTS IN THAT REGION.
IN ALASKA, SOUTHERLY FLOW IS FORECAST FOR APPROXIMATELY THE EASTERN HALF OF THE
STATE BRINGING ENHANCED ABOVE-NORMAL TEMPERATURES CHANCES. CLOSER TO THE MEAN
TROUGH AXIS JUST OFF THE WEST COAST OF ALASKA, NEAR- TO BELOW-NORMAL
TEMPERATURES ARE FAVORED ACROSS THE WESTERN HALF OF ALASKA. MEANWHILE,
ABOVE-NORMAL TEMPERATURES ARE FAVORED FOR HAWAII BASED ON THE TEMPERATURE
CONSOLIDATION TOOL.
THE DEVELOPMENT OF A FULL-LATITUDE TROUGH OVER THE EASTERN PACIFIC AND BERING
SEA EARLY IN WEEK-2 LEADS TO INCREASED CHANCES OF ABOVE-NORMAL PRECIPITATION
FOR THE ENTIRE WEST COAST. SHORTWAVE ACTIVITY ASSOCIATED WITH IT, AND FROM THE
EARLIER 6-10 DAY PERIOD, EXTENDS THE INCREASED CHANCES OF ABOVE-NORMAL
PRECIPITATION INLAND ACROSS MOST OF THE SOUTHERN AND CENTRAL THIRDS OF THE
CONUS. DISPLACED FROM THE PRIMARY STORMTRACK, THE AREA FROM THE NORTHERN
ROCKIES EASTWARD ACROSS THE NORTHERN TIER TO THE CENTRAL GREAT LAKES REGION IS
FAVORED TO GET BELOW-NORMAL PRECIPITATION, THOUGH THIS REGION OF FAVORED
ANOMALOUS DRYNESS CONTINUES TO DECREASE IN SIZE. UNCALIBRATED PRECIPITATION
GUIDANCE FROM THE THREE ENSEMBLES DURING THE FIRST HALF OF WEEK-2 FAVORS A WET
PATTERN ACROSS THE SOUTH-CENTRAL STATES, AS SURFACE HIGH PRESSURE LOCATED OVER
THE SOUTHEAST HELPS TO CHANNEL LOW-LEVEL GULF MOISTURE INTO THIS AREA.
INCREASED THUNDERSTORM ACTIVITY IS ALSO POSSIBLE, WITH THE GENERAL REGION OF
STORMINESS SHIFTING EASTWARD INTO THE SOUTHEAST CONUS DURING THE SECOND HALF OF
THE PERIOD. ALL THREE ENSEMBLES PREDICT A COASTAL STORM NEAR THE SOUTHEAST
COAST SHORTLY AFTER CHRISTMAS, WHICH MAY AFFECT HOLIDAY TRAVEL. AT THIS EARLY
DATE, THE SOUTHEAST IS THE AREA OF GREATEST CONCERN, WITH LOWER CONFIDENCE
FARTHER UP THE COAST. FOR ALASKA, ABOVE-NORMAL PRECIPITATION REMAINS FAVORED
FOR MOST OF THE STATE IN ADVANCE OF A DEEP MID-LEVEL TROUGH WITH THE GREATEST
CHANCES IN SOUTH- CENTRAL AND SOUTHEAST ALASKA. THE PRECIPITATION CONSOLIDATION
TOOL FAVORS BELOW-NORMAL PRECIPITATION FOR ALL THE HAWAIIAN ISLANDS, ASSOCIATED
WITH THE ANTICIPATED DEPARTURE OF A MID-LEVEL TROUGH THAT IS FORECAST TO AFFECT
THE ISLAND CHAIN DURING THE EARLIER 6-10 DAY PERIOD.
THE OFFICIAL 8-14 DAY 500-HPA HEIGHT BLEND CONSISTS OF: 33% OF TODAY'S 0Z GFS
ENSEMBLE MEAN CENTERED ON DAY 11, 34% OF TODAY'S 0Z EUROPEAN ENSEMBLE MEAN
CENTERED ON DAY 11, AND 33% OF TODAY'S 0Z CANADIAN ENSEMBLE MEAN CENTERED ON
DAY 11
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: NEAR AVERAGE, 3 OUT OF 5 DUE TO
GENERALLY GOOD AGREEMENT AMONG THE 500-HPA HEIGHT FORECASTS, OFFSET BY GREATER
DIFFERENCES AMONG THE PRECIPITATION TOOLS.
FORECASTER: ANTHONY A
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 1991-2020 BASE PERIOD MEANS AS REFERENCE IN
THE CLIMATE OUTLOOKS.
THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON
DECEMBER 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:
19901209 - 20031203 - 19931125 - 19581229 - 19651205
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:
19651204 - 19591218 - 19971213 - 20031203 - 19861129
6-10 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 21 - 25 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A N
SRN CALIF A A IDAHO A B NEVADA A A
W MONTANA A B E MONTANA A B WYOMING A N
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO A A N DAKOTA A B S DAKOTA A A
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA A A IOWA A A MISSOURI A A
ARKANSAS A A LOUISIANA A A WISCONSIN A A
ILLINOIS A A MISSISSIPPI A A MICHIGAN A N
INDIANA A A OHIO A B KENTUCKY A N
TENNESSEE A N ALABAMA A A NEW YORK A B
VERMONT A B NEW HAMP A B MAINE A B
MASS A B CONN A B RHODE IS A B
PENN A B NEW JERSEY A B W VIRGINIA A B
MARYLAND A B DELAWARE A B VIRGINIA A B
N CAROLINA A B S CAROLINA A N GEORGIA A N
FL PNHDL A A FL PENIN N A AK N SLOPE N A
AK ALEUTIAN B N AK WESTERN N A AK INT BSN N A
AK S INT N A AK SO COAST N A AK PNHDL A A
8-14 DAY OUTLOOK TABLE
OUTLOOK FOR DEC 23 - 29 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF A A IDAHO A B NEVADA A A
W MONTANA A B E MONTANA A B WYOMING A B
UTAH A A ARIZONA A A COLORADO A A
NEW MEXICO A A N DAKOTA A B S DAKOTA A N
NEBRASKA A A KANSAS A A OKLAHOMA A A
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA A B IOWA A A MISSOURI A A
ARKANSAS A A LOUISIANA A A WISCONSIN A N
ILLINOIS A A MISSISSIPPI A A MICHIGAN A N
INDIANA A A OHIO A A KENTUCKY A A
TENNESSEE A A ALABAMA A A NEW YORK A N
VERMONT A N NEW HAMP A N MAINE A N
MASS A N CONN A N RHODE IS A N
PENN A A NEW JERSEY A A W VIRGINIA A A
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A A S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN N A AK N SLOPE N A
AK ALEUTIAN B N AK WESTERN B N AK INT BSN A A
AK S INT A A AK SO COAST A A AK PNHDL A 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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