088
FXUS02 KWBC 011900
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 PM EDT TUE OCT 1 2024
VALID 12Z FRI OCT 04 2024 - 12Z TUE OCT 08 2024
...ANOMALOUS HEAT WILL PERSIST ACROSS THE SOUTHWEST INTO THE
WEEKEND...
..OVERVIEW
LATEST MODELS AND ENSEMBLES CONTINUE TO SHOW A PATTERN TRANSITION
FROM PROGRESSIVE NORTHERN TIER FLOW LATE THIS WEEK TOWARD AN
AMPLIFYING EASTERN U.S./ATLANTIC COAST TROUGH EARLY NEXT WEEK WHILE
A MEAN RIDGE COVERING MUCH OF THE WEST EXTENDS INTO THE PLAINS,
PRODUCING AN EXTENDED PERIOD OF UNSEASONABLY WARM TO HOT WEATHER.
SEPARATE FRONTS AFFECTING THE NORTHEAST AND NORTHWEST LATE THIS
WEEK SHOULD GENERATE MAINLY LIGHT RAIN, BUT A FRONT AND POTENTIAL
EMBEDDED SURFACE SYSTEM REACHING NEAR THE EAST COAST NEXT WEEK
COULD SUPPORT MORE ORGANIZED RAINFALL OVER THAT REGION. FARTHER
SOUTH, NOT MUCH HAS CHANGED REGARDING THE OVERALL FORECAST
EVOLUTION FAVORING LOW PRESSURE AND HEAVY RAINFALL POTENTIAL OVER
THE GULF OF MEXICO WITH SOME POCKETS OF ENHANCED MOISTURE POSSIBLY
EXTENDING INTO SOME AREAS ALONG THE GULF COAST, BUT WITH POOR
AGREEMENT/CONSISTENCY FOR DETAILS. THERE MAY BE MULTIPLE SURFACE
FEATURES TO FOCUS RAINFALL, INCLUDING ONE LIFTING FROM THE
NORTHWESTERN CARIBBEAN INTO THE GULF AND ANOTHER THAT MAY BE OVER
THE WESTERN GULF, WITH SOME POTENTIAL FOR THESE TO COMBINE INTO
EARLY NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE AGREEMENT FOR NORTHERN STREAM FLOW LATE THIS WEEK INTO
THE WEEKEND HAS BEEN RATHER GOOD OTHER THAN A LINGERING STRAY
SOLUTION OR TWO. THE 00Z CMC SEEMED TO BE THE BIGGEST OUTLIER AS IT
SHOWED A CLOSED LOW EMBEDDED WITHIN THE TROUGH ATOP THE UPPER
MIDWEST TO GREAT LAKES SUNDAY-MONDAY UNLIKE OTHER MODELS WITH THEIR
PHASED TROUGH. TROUGH DETAILS BECOME MORE OF A QUESTION MARK
TOWARD THE EAST COAST BY NEXT MONDAY-TUESDAY AS ENERGY PIVOTS
EASTWARD. GFS RUNS LATELY HAVE INDICATED AN UPPER LOW CLOSING OFF
NEAR NEW ENGLAND AND THE NEARBY WESTERN ATLANTIC BY TUESDAY, WITH
THE 00/12Z RUNS SHOWING FAIRLY SIMILAR POSITION WHILE THE 06Z WAS
MORE NORTH. WHILE EC RUNS WERE DISPLAYING A CLOSED UPPER LOW ALBEIT
A BIT FARTHER SOUTH TOWARD THE MID-ATLANTIC, THE NEW 12Z EC HAS
BECOME MORE LIKE THE AI/ML MODELS BY SHOWING A PHASED TROUGH. THESE
DIFFERENCES WILL ALSO AFFECT THE ASSOCIATED SURFACE LOW'S DEPTH
AND POSITION NEAR NEW ENGLAND; 12Z MODEL RUNS ARE GENERALLY WEAKER
THAN THE 00Z/06Z GUIDANCE. ALSO WORTH KEEPING AN EYE ON, BY TUESDAY
A FEW ML MODELS SHOW MORE POTENTIAL FOR A SHORTWAVE FROM HUDSON
BAY SOUTH/SOUTHWESTWARD VERSUS WHAT MOST DYNAMICAL GUIDANCE SHOWS.
THE 12Z CMC ALSO GOES ALL IN ON THIS ENERGY, DIGGING IT INTO THE
MIDWEST BY TUESDAY, UNLIKE OTHER MODELS.
THE FORECAST OVER AND NEAR THE GULF OF MEXICO CONTINUES TO HAVE
LOW PREDICTABILITY DUE TO A COMBINATION OF SMALLER-SCALE FEATURES.
ONE WAVE MAY TRACK INTO THE CENTRAL/EAST-CENTRAL GULF FROM THE
NORTHWESTERN CARIBBEAN WHILE ANOTHER FEATURE MAY EVOLVE OVER THE
WESTERN GULF, WITH THE SURFACE/QPF DETAILS ALSO POTENTIALLY
AFFECTED BY ENERGY ALOFT OVER TEXAS AND NEARBY AREAS. PER
COORDINATION WITH NHC, THESE FEATURES MAY PHASE AT SOME POINT NEXT
WEEK AS THEY APPROACH AND INTERACT. GUIDANCE SHOWS THE SYSTEM(S)
COULD LINGER AND MEANDER OVER THE GULF EVEN INTO THE MIDDLE OF NEXT
WEEK. THIS APPEARS TO BE A MESSY EVOLUTION AS FRONTS AND MOISTURE
GRADIENTS ARE ALSO EVIDENT NEARBY. CONTINUE TO MONITOR OUTLOOKS
FROM THE NATIONAL HURRICANE CENTER FOR THE LATEST INFORMATION ON
FEATURES OF INTEREST.
FOR THE MOST PART, AN OPERATIONAL MODEL BLEND FAVORING THE GFS AND
ECMWF SUFFICED FOR THE EARLY PART OF THE FORECAST. THE CMC WAS
USED MINIMALLY AND ONLY EARLY ON AS IT DIVERGED WITH THE NORTH-
CENTRAL U.S. SHORTWAVE. BY MID-PERIOD, INCLUDED SOME OF THE GEFS
AND EC ENSEMBLE MEANS, AND BY DAY 7 INCREASED THE PROPORTION OF THE
MEANS TO OVER HALF CONSIDERING THE INDIVIDUAL MODEL DIFFERENCES
ESPECIALLY WITH THE EASTERN TROUGHING/LOW PRESSURE.
..WEATHER/HAZARDS HIGHLIGHTS
VERY LITTLE HAS CHANGED OVER THE PAST DAY IN TERMS OF THE LOW
CONFIDENCE FOR WHERE AREAS OF HEAVY RAIN COULD EXTEND INTO SOME
COASTAL/INLAND AREAS NEAR THE GULF COAST DURING THE PERIOD. FOR THE
FRIDAY-SATURDAY TIME FRAME COVERED BY THE DAYS 4-5 EXCESSIVE
RAINFALL OUTLOOKS, THERE ARE MINORITY MODEL SOLUTIONS
SHOWING POCKETS OF ENHANCED RAINFALL ALONG PARTS OF THE
CENTRAL/EAST-CENTRAL GULF COAST AND/OR THE TEXAS COAST. HOWEVER
WHILE SEPARATE ENSEMBLE SYSTEMS DIFFER OVER WHERE THE BEST HEAVY
RAIN POTENTIAL WILL BE OVER THE GULF, THEY DO NOT EXTEND THEIR
BETTER PROBABILITIES TO LAND. THE COMBINATION OF POOR GUIDANCE
CLUSTERING/CONTINUITY AND HIGH FLASH FLOOD GUIDANCE VALUES ALONG
THE GULF COAST REGION CONTINUE TO FAVOR NOT DEPICTING ANY RISK
AREAS ON THE DAYS 4-5 EROS. RECENT GUIDANCE HAS BEEN SUGGESTING
THAT SOME HEAVY RAIN MAY EVENTUALLY SPREAD ACROSS FLORIDA BY EARLY
NEXT WEEK, PERHAPS AIDED BY A FRONT APPROACHING FROM THE NORTH.
FROM FRIDAY THROUGH THE WEEKEND, EXPECT LIGHTER RAINFALL ALONG
PORTIONS OF THE FRONTS SUPPORTED BY NORTHERN STREAM DYNAMICS. ONE
FRONT MAY PRODUCE AREAS OF LIGHT RAIN OVER THE NORTHEAST LATE THIS
WEEK WHILE A FRONT REACHING THE PACIFIC NORTHWEST AROUND FRIDAY
MAY PRODUCE SOME LIGHT RAIN AS WELL. A FRONTAL SYSTEM AND POSSIBLE
DEVELOPING EMBEDDED LOW MAY PRODUCE MORE ORGANIZED RAINFALL FROM
THE GREAT LAKES REGION TO THE EAST COAST BY NEXT MONDAY-TUESDAY.
COVERAGE AND MAGNITUDE WILL DEPEND ON SYSTEM SPECIFICS THAT HAVE
LOWER CONFIDENCE AT THIS TIME. AN APPROACHING PACIFIC FRONT MAY
BRING LIGHT RAIN TO THE NORTHERN PACIFIC NORTHWEST EARLY NEXT WEEK.
THE STRONG AND PERSISTENT UPPER RIDGE COVERING THE WEST AND
EXTENDING INTO THE PLAINS WILL SUPPORT A LENGTHY PERIOD OF WELL
ABOVE NORMAL TEMPERATURES OVER MANY PARTS OF THE WESTERN/CENTRAL
U.S. HIGHS 10-20F OR SO ABOVE NORMAL WILL BE COMMON AND NUMEROUS
DAILY RECORDS APPEAR LIKELY FROM THE SOUTHERN HALF OF THE WEST
INTO PARTS OF THE HIGH PLAINS, ESPECIALLY FRIDAY-SUNDAY. EASTERN
U.S. TEMPERATURES WILL VARY IN THE NEAR TO ABOVE NORMAL RANGE UNTIL
THE EAST COAST TROUGH DROPS SOME HIGHS MODERATELY BELOW NORMAL NEXT
TUESDAY.
TATE/RAUSCH
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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