349
FXUS02 KWBC 062011
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
411 PM EDT SUN OCT 6 2024
VALID 12Z WED OCT 09 2024 - 12Z SUN OCT 13 2024
...HURRICANE MILTON COULD BRING LIFE-THREATENING IMPACTS ACROSS
PARTS OF FLORIDA THROUGH WEDNESDAY...
..OVERVIEW
HURRICANE MILTON IS CURRENTLY LOCATED IN THE WESTERN GULF OF
MEXICO AND IS FORECAST TO CONTINUE TO TRACK GENERALLY EAST-
NORTHEASTWARD ACROSS THE GULF WHILE STRENGTHENING A MAJOR
HURRICANE. MILTON SHOULD BE APPROACHING THE WEST COAST OF THE
FLORIDA PENINSULA BY EARLY WEDNESDAY, AND THOUGH IT MAY WEAKEN A
BIT BEFORE LANDFALL, HEAVY RAINFALL/FLOODING, HIGH WIND, AND STORM
SURGE ARE ALL SIGNIFICANT THREATS. ELSEWHERE, AN UPPER TROUGH
(ANCHORED BY AN UPPER LOW THAT MAY TRACK OVER OR NEAR NEW ENGLAND)
WILL MOVE THROUGH THE EAST MIDWEEK WHILE AN UPSTREAM UPPER RIDGE
TRACKS FROM THE WEST TO CENTRAL U.S. BRINGING A PERIOD OF
CLIMATOLOGICALLY WARM WEATHER. BY LATER THIS WEEK, A PACIFIC TROUGH
MAY PUSH INLAND OVER THE WEST WITH SOME GENERALLY LIGHT
PRECIPITATION TO ACCOMPANY.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE CONTINUES TO SUGGEST MILTON WILL STRENGTHEN INTO A
POSSIBLY MAJOR HURRICANE AS IT TRACKS EAST ACROSS THE GULF. THERE
REMAIN SOME NORTH-SOUTH WOBBLES AND UNCERTAINTY IN THE TIMING, WITH
PLENTY OF RUN TO RUN VARIABILITY. THE CMC REMAINS THE SLOWEST OF
THE DETERMINISTIC MODELS AS IT HAS FOR MULTIPLE DAYS. UKMET RUNS
ARE ON THE SOUTHERN SIDE, WHILE THE 12Z GFS CAME IN A BIT NORTH
WITH THE TRACK AND QPF AXIS. THE 00Z AND 12Z ECMWF RUNS ARE GOOD
MIDDLE GROUND SOLUTIONS AND ARE CLOSEST TO THE OFFICIAL TRACK FROM
THE NHC. TIMING VARIABILITY ALSO EVIDENT IN THE LATEST RUNS OF THE
AI/ML MODELS AS WELL. MILTON MAY TRANSITION TO EXTRATROPICAL QUITE
QUICKLY THURSDAY AFTER IT CROSSES THE FLORIDA PENINSULA.
FARTHER NORTH WITH THE MAIN JET STREAM, MODELS ARE REASONABLY
AGREEABLE WITH THE PATTERN EARLY IN THE PERIOD. THE 00/06Z AND NOW
NEWER 12Z GUIDANCE HAS BECOME MORE AGREEABLE IN SHOWING AN UPPER
TROUGH IN SOUTH-CENTRAL CANADA FRIDAY AND MOVING INTO THE GREAT
LAKES SATURDAY THAT COULD SERVE TO SHUNT THE NORTHERN EXTENT OF THE
UPPER RIDGE SOUTHWARD, ALONG WITH PUSHING A COLD FRONT
SOUTHEASTWARD COMPARED TO CONTINUITY. THEN ACROSS THE WEST, THE
TIMING OF A TROUGH APPROACHING FROM THE EASTERN PACIFIC GETS QUITE
UNCERTAIN LATE WEEK INTO THE WEEKEND WITHOUT MUCH MODEL OR RUN-TO-
RUN AGREEMENT AT ALL. RECENT MODELS ARE GENERALLY SHALLOWER WITH
THE TROUGH COMPARED TO OLDER RUNS, LEADING TO LESS SUPPORT FOR
MODERATE TO HEAVY QPF IN THE INTERIOR WEST. AS OF THE 00Z/06Z
CYCLE, THE CMC APPEARED TO BE A FAST OUTLIER COMPARED TO THE
GFS/EC. GUIDANCE HAS GENERALLY SLOWED IN THE 12Z CYCLE, SO THE 12Z
CMC'S TIMING OF THE TROUGH/POSSIBLE EMBEDDED UPPER LOW PROGRESSION
IS NOW PRETTY SIMILAR TO THE 00/06Z RUNS OF THE GFS AND EC, WHILE
THE 12Z GFS/EC HAVE SLOWED EVEN FURTHER. EXPECT CHANGES TO THIS
ASPECT OF THE FORECAST SINCE MODELS ARE WAFFLING SO MUCH AT THIS
TIME.
THE WPC FORECAST WAS BASED ON A BLEND OF THE DETERMINISTIC 00Z
ECMWF, 06Z GFS, AND SOME 00Z UKMET EARLY IN THE PERIOD, WITH
INCREASING PROPORTIONS OF THE ENSEMBLE MEANS TO HALF BY DAY 6 AND
OVER HALF DAY 7 GIVEN THE UNCERTAINTY PARTICULARLY IN THE WEST.
..WEATHER/HAZARDS HIGHLIGHTS
MILTON IS FORECAST TO BE A MAJOR HURRICANE AS IT APPROACHES THE
WEST COAST OF FLORIDA BY THE START OF THE MEDIUM RANGE PERIOD
WEDNESDAY. THERE IS AN INCREASING RISK OF LIFE-THREATENING STORM
SURGE AND WIND IMPACTS FOR PORTIONS OF THE WEST COAST OF THE
FLORIDA PENINSULA BEGINNING POTENTIALLY EVEN TUESDAY NIGHT.
RESIDENTS IN THESE AREAS SHOULD FOLLOW ANY ADVICE GIVEN BY LOCAL
OFFICIALS, AND CHECK BACK FOR UPDATES TO THE FORECAST. 5 TO 10
INCHES OF RAINFALL WITH LOCAL AMOUNTS TO 15 INCHES IS POSSIBLE FOR
PARTS OF THE FLORIDA PENINSULA, BUT THE EXACT AXIS IS STILL
UNCERTAIN AND DEPENDENT ON ON THE TRACK MILTON TAKES ACROSS
FLORIDA. THE HIGHEST AMOUNTS ARE LIKELY TO BE ALONG MILTON'S TRACK
AND NORTH CLOSER TO THE SURFACE FRONT AND UPPER SUPPORT. REGARDLESS
OF THE UNCERTAINTY, THE ERO FOR DAY 4/WEDNESDAY CONTINUES TO SHOW
A MODERATE RISK ACROSS NORTH-CENTRAL PORTIONS OF THE PENINSULA,
INCLUDING THE METRO AREAS OF TAMPA BAY AND ORLANDO AND JUST SOUTH
OF JACKSONVILLE, WITH MINIMAL CHANGES TO THE PREVIOUS ISSUANCE. BY
THURSDAY, THE HEAVIEST RAINFALL ASSOCIATED WITH MILTON SHOULD BE
OFFSHORE OF FLORIDA, THOUGH CONTINUE TO DEPICT A MARGINAL RISK FOR
NORTHEAST FL TO ACCOUNT FOR POSSIBLY SLOWER SPEED.
ELSEWHERE, THE UPPER LOW OVER/NEAR NEW ENGLAND SHOULD ALLOW FOR
SOME LAKE-ENHANCED RAIN WITHIN WESTERLY FLOW ACROSS THE GREAT
LAKES/INTERIOR NORTHEAST ON WEDNESDAY. A FRONT PASSING THROUGH THE
PACIFIC NORTHWEST BY MIDWEEK SHOULD PRODUCE SOME LIGHT RAIN AND
NONZERO CHANCES OF SNOW IN THE HIGHEST ELEVATIONS. THEN ANOTHER
ROUND OF PRECIPITATION IS LIKELY TO COME INTO THE WEST WITH UPPER
TROUGHING ON FRIDAY, FOR MODERATE AMOUNTS OF RAIN AND SOME HIGHER
ELEVATION SNOW IN THE PACIFIC NORTHWEST. PRECIPITATION AMOUNTS INTO
THE INTERIOR WEST LATE WEEK-WEEKEND ARE MORE UNCERTAIN RELATED TO
THE EVOLUTION OF THE TROUGH.
THE STRONG AND PERSISTENT WESTERN-CENTRAL U.S. UPPER RIDGE WILL
PROMOTE AN EXTENDED PERIOD OF WELL ABOVE NORMAL TEMPERATURES OVER
THAT PART OF THE COUNTRY. THE HIGHEST ANOMALIES ARE LIKELY FOR THE
NORTHERN PLAINS BY WEDNESDAY-THURSDAY, AND SOME LOCATIONS SHOULD
REACH 20-30F ABOVE NORMAL AS HIGHS IN THE 80S MAY EXTEND TO THE
CANADIAN BORDER. NORTHERN STREAM TROUGHING AND A COLD FRONT COULD
PUSH THE GREATEST WARM ANOMALIES SOUTHEAST INTO THE CENTRAL PLAINS
AND MID/UPPER MISSISSIPPI VALLEY FRIDAY-SATURDAY. MEANWHILE HEIGHT
FALLS SLOWLY PUSHING IN OVER THE WEST COAST WILL SUPPORT A TREND
TOWARD NEAR NORMAL TEMPERATURES BY WEDNESDAY OR THURSDAY. HOWEVER,
TEMPERATURES AROUND 10 DEGREES ABOVE NORMAL IN THE SOUTHWEST COULD
SET ADDITIONAL DAILY RECORDS THOUGH THE TEMPERATURES HAVE MODERATED
COMPARED TO RECENT DAYS AND THE SHORT RANGE. MEANWHILE, COOLER
THAN AVERAGE TEMPERATURES ARE FORECAST ACROSS MOST OF THE EAST AS
UPPER TROUGHING SETS UP NEAR THE EAST COAST, WITH SOME POTENTIAL
FROST/FREEZE CONCERNS ACROSS PORTIONS OF THE GREAT LAKES REGION
INTO THE APPALACHIANS AND INTERIOR NORTHEAST. EXPECT TEMPERATURES
TO MODERATE NEXT WEEKEND AS THE UPPER LOW SCOOTS OUT OF THE REGION.
TATE/SANTORELLI
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC MEDIUM
RANGE HAZARDS OUTLOOK CHART AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,
QUANTITATIVE PRECIPITATION FORECAST (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=ERO
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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