431
FXUS02 KWBC 061900
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 PM EST WED NOV 6 2024
VALID 12Z SAT NOV 09 2024 - 12Z WED NOV 13 2024
..WATCHING HURRICANE RAFAEL AS IT TRACKS INTO THE GULF OF MEXICO
..OVERVIEW
THE NATIONAL HURRICANE CENTER CONTINUES TO ISSUE ADVISORIES FOR
HURRICANE RAFAEL AS IT TRACKS ACROSS THE GULF THIS WEEKEND INTO
EARLY NEXT WEEK WHILE WEAKENING AS IT INTERACTS WITH A MEAN UPPER
RIDGE STRETCHING FROM THE BAHAMAS. MODELS AND THE NHC FORECAST HAVE
TRENDED FARTHER SOUTH WITH RAFAEL, KEEPING IT OFFSHORE WELL SOUTH
OF THE CENTRAL GULF COAST WHILE IT WEAKENS. BUT THE COMBINATION OF
RAFAEL'S MOISTURE AND A FRONTAL SYSTEM SUPPORTED BY AN UPPER LOW
EJECTING NORTHEAST FROM THE PLAINS MAY PRODUCE SOME AREAS OF
LOCALLY HEAVY RAINFALL FROM THE GULF COAST NORTHWARD ESPECIALLY
THIS WEEKEND. MEANWHILE, A SERIES OF PACIFIC SYSTEMS WILL INCREASE
COVERAGE OF RAIN AND HIGHER ELEVATION SNOW OVER THE WEST FROM THE
WEEKEND INTO EARLY NEXT WEEK. MUCH OF THE EAST SHOULD SEE ABOVE
NORMAL TEMPERATURES THROUGH THE PERIOD WHILE THE SOUTHERN ROCKIES
WILL START THE WEEKEND ON THE CHILLY SIDE AND COOLER TEMPERATURES
WILL SPREAD ACROSS THE WEST NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
FOR HURRICANE RAFAEL, RECENT MODEL RUNS HAVE GENERALLY TRENDED TO
THE SOUTH, SHOWING THE SURFACE LOW WEAKENING OVER THE GULF RATHER
THAN MAKING LANDFALL IN THE CENTRAL GULF COAST AS SOME PREVIOUS
RUNS HAD SHOWED. THE 00Z ECMWF, UKMET, AND MANY EC ENSEMBLE MEMBERS
WERE PARTICULARLY AGGRESSIVE WITH THIS SOUTHWESTWARD SHIFT AS
RAFAEL DOES NOT GET PICKED UP BY THE UPPER TROUGH TO TRACK IT
NORTHWARD. GFS RUNS ARE INDICATING THIS TREND BUT NOT TO THE EXTENT
OF THE EC/UKMET THAT TAKE RAFAEL SO FAR SOUTH IT GOES INTO CENTRAL
MEXICO. THE 12Z CMC DOES HAVE RAFAEL TRACK NORTH INTO THE CENTRAL
GULF COAST, ALONG WITH SOME GEFS MEMBERS AND THE BULK OF THE AI/ML
MODELS INITIALIZED AT 00Z, SO THERE REMAINS UNCERTAINTY WITH THIS
TREND. CONTINUE TO MONITOR LATEST NHC PRODUCTS FOR ADDITIONAL
INFORMATION ON RAFAEL.
FARTHER NORTH, THE FIRST SYSTEM OF NOTE IS A CLOSED UPPER LOW
STARTING THE PERIOD SATURDAY ATOP THE CENTRAL HIGH PLAINS AND
TRACKING NORTHEAST SUNDAY-MONDAY WHILE OPENING UP. MODEL GUIDANCE
IS RATHER AGREEABLE WITH THIS FEATURE ESPECIALLY OVER THE WEEKEND,
BUT GUIDANCE HAS BEEN MORE ERRATIC WITH DETAILS OF A SHORTWAVE THAT
ENTERS WESTERN NORTH AMERICA DURING THE WEEKEND AND MAY HAVE SOME
INFLUENCE ON THE REMAINING UPPER LOW ENERGY BY EARLY NEXT WEEK. THE
00Z CMC IN PARTICULAR SEEMED LIKE AN EASTERN OUTLIER WITH THIS
SHORTWAVE FOR MORE INTERACTION WITH THE PREEXISTING UPPER
LOW/TROUGH. THIS LEADS TO LINGERING UNCERTAINTY FOR SOME DETAILS OF
THE FRONTAL SYSTEM REACHING THE NORTHEAST.
THERE ARE CONTINUED TIMING AND AMPLITUDE DIFFERENCES FOR THE
LARGER SCALE TROUGH MOVING INTO/THROUGH THE WEST EARLY NEXT WEEK
AND TOWARD THE CENTRAL U.S. BY MIDWEEK, WITH GFS RUNS LEANING
SLOWER AND ECMWF FASTER. LATEST ML MODELS SHOW A SIMILAR SPREAD,
ARGUING FOR A BLEND/COMPROMISE APPROACH. THIS ALSO MITIGATES ISSUES
FOR HOW ENERGY MAY BE DISTRIBUTED WITHIN THE UPPER TROUGH BY THE
MIDDLE OF NEXT WEEK, WITH INDIVIDUAL SOLUTIONS RANGING BETWEEN
GREATER DYNAMICS IN THE NORTHERN PART OF THE TROUGH, OR FARTHER
SOUTH, TO AN EVENLY PHASED TROUGH. A COMPROMISE ALSO LOOKS BEST FOR
THE NEXT SYSTEM THAT MAY COME INTO THE PICTURE OVER THE
NORTHEASTERN PACIFIC BY NEXT WEDNESDAY.
OVERALL A BLEND FAVORING THE 06Z GFS AND 00Z ECMWF WITH LESSER
PORTIONS OF THE UKMET AND GEFS/EC ENSEMBLE MEANS EARLY IN THE
PERIOD, WITH AN INCREASING PROPORTION OF THE ENSEMBLE MEANS AS THE
PERIOD PROGRESSED GIVEN INCREASING UNCERTAINTY.
..WEATHER/HAZARDS HIGHLIGHTS
THE COMBINATION OF THE PLAINS SYSTEM PUSHING INTO THE MISSISSIPPI
VALLEY AND MOISTURE FROM RAFAEL, WHICH IS FORECAST TO BE SOUTH OF
THE CENTRAL GULF COAST BY THE WEEKEND, WILL LEAD TO THE POTENTIAL
FOR SOME AREAS OF HEAVY RAINFALL FROM THE CENTRAL GULF COAST TO THE
OHIO VALLEY THIS WEEKEND. ON SATURDAY, MAINTAINED THE MARGINAL
RISK IN THE ERO WITH GENERALLY MINOR CHANGES FROM THE PREVIOUS
FORECAST. BY SUNDAY, GOOD MOISTURE AND SOME LIMITED INSTABILITY
SHOULD CONTINUE TO SPREAD INTO SIMILAR REGIONS, SHUNTED JUST A BIT
EASTWARD. THIS FORECAST CYCLE, WPC HAS STRETCHED THE MARGINAL RISK
WELL NORTH ACROSS PARTS OF THE LOWER MISSISSIPPI VALLEY TO MID-
SOUTH TO THE OHIO VALLEY WHERE MODERATE TO HEAVY RAINFALL RATES MAY
TRAIN IN THE VICINITY OF THE FRONTAL SYSTEM. THE AREAL COVERAGE
MAY BE ABLE TO SHRINK WITH TIME IF MODELS CONVERGE. DRY ANTECEDENT
CONDITIONS IN THE OHIO VALLEY IN PARTICULAR MAY LIMIT THE EXTENT OF
IMPACTS OF FLASH FLOODING FROM HEAVY RAIN, BUT A 5 PERCENT RISK
(MARGINAL) SEEMS WARRANTED. SOME RAINFALL MAY LINGER BEYOND SUNDAY
BUT MOST OF THE EAST SHOULD TREND DRIER BY MONDAY-TUESDAY. ALSO OF
NOTE, A WAVE TRACKING FROM THE SOUTHERN BAHAMAS INTO THE EASTERN
GULF MAY INCREASE RAINFALL OVER FLORIDA AROUND SUNDAY-MONDAY.
THE WEST WILL SEE A WETTER REGIME WITH HIGH ELEVATION SNOW,
STARTING IN THE PACIFIC NORTHWEST AND THEN SPREADING FARTHER SOUTH
INTO PARTS OF CALIFORNIA AND EAST INTO THE ROCKIES. HIGHEST TOTALS
SHOULD BE IN THE SUNDAY-MONDAY TIME FRAME WITH A VIGOROUS UPPER
TROUGH AND FRONTAL SYSTEM APPROACHING/REACHING THE AREA. WHILE
THERE IS STILL A FAIR AMOUNT OF SPREAD FOR QPF MAGNITUDES, FIRST-
GUESS GUIDANCE IS SHOWING ENOUGH OF A SIGNAL TO INTRODUCE A
MARGINAL RISK AREA IN THE DAY 5 ERO OVER PARTS OF THE PACIFIC
NORTHWEST WHERE INITIAL SOIL CONDITIONS ARE NEUTRAL TO DAMP. HIGHER
ELEVATION SNOW IS LIKELY FOR THE CASCADES, SIERRA NEVADA, AND
NORTHERN/CENTRAL ROCKIES. ANOTHER SYSTEM IS LIKELY TO BRING
ADDITIONAL FOCUSED PRECIPITATION TO THE PACIFIC NORTHWEST NEXT
WEDNESDAY. DEPENDING ON WESTERN UPPER TROUGH PROGRESSION, SOME
RAINFALL MAY DEVELOP OVER THE CENTRAL U.S. BY THE MIDDLE OF NEXT
WEEK.
EXCEPT FOR THE GREAT LAKES INTO NEW ENGLAND DURING THE WEEKEND,
THE EASTERN HALF OF THE COUNTRY WILL LIKELY SEE ABOVE NORMAL
TEMPERATURES THROUGH THE PERIOD. WARMEST ANOMALIES SHOULD BE FOR
MORNING LOWS, REACHING 20-25F ABOVE NORMAL ON ONE OR MORE DAYS OVER
THE SOUTH AND EXTENDING A LITTLE FARTHER NORTHEASTWARD AT TIMES.
COVERAGE OF PLUS 10-15F ANOMALIES FOR HIGHS SHOULD INCREASE GOING
FROM THE WEEKEND INTO THE FIRST HALF OF NEXT WEEK. CORRESPONDING TO
THESE RELATIVE ANOMALIES, THERE WILL BE BETTER POTENTIAL FOR SOME
RECORD WARM LOWS VERSUS MORE ISOLATED RECORDS FOR DAYTIME HIGHS.
THE NORTHERN PLAINS WILL ALSO BE WELL ABOVE NORMAL UNTIL A COOLING
TREND TUESDAY-WEDNESDAY, WHILE THE SOUTHERN PLAINS WILL BE WARMEST
EARLY NEXT WEEK. CHILLY TEMPERATURES OVER THE SOUTHERN ROCKIES/HIGH
PLAINS WILL GRADUALLY MODERATE WHILE MUCH OF THE WEST WILL BE NEAR
NORMAL DURING THE WEEKEND. THEN THE UPPER TROUGH PUSHING INTO THE
WEST NEXT WEEK SHOULD EXPAND THE COVERAGE OF BELOW NORMAL
TEMPERATURES FROM WEST TO EAST.
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.PHPSCHICHTEL/HAMRICK
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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