088
FXUS02 KWBC 280627
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
227 AM EDT SUN JUL 28 2024
VALID 12Z WED JUL 31 2024 - 12Z SUN AUG 04 2024
...HAZARDOUS HEAT TO SHIFT FROM THE SOUTH-CENTRAL PLAINS EARLY
PERIOD TO THE NORTHWEST LATER NEXT WEEK...
..OVERVIEW
GUIDANCE CONTINUES TO SHOW A PATTERN EVOLVING FROM A SOUTHERN
ROCKIES/PLAINS UPPER RIDGE EARLIER IN THE WEEK TO AN AMPLIFYING
WESTERN RIDGE LATER IN THE WEEK. THIS WOULD HELP SET UP A PROLONGED
PERIOD OF HOT WEATHER OVER MANY AREAS WITH THE MOST ANOMALOUS HEAT
EXPECTED OVER CENTRAL PARTS OF THE PLAINS EARLY TO MIDWEEK. WARMER
THAN NORMAL TEMPERATURES ARE FORECAST TO EXPAND NORTH TOWARD THE
U.S./CANADIAN BORDER LATER IN THE WEEK, DESPITE SHORTWAVE ENERGY
MOVING THROUGH THE MIDWEST AND EVENTUALLY DEVELOPING MEAN TROUGHING
OVER THE EASTERN U.S. THAT WILL SUPPORT A BROAD AREA OF
SHOWERS/THUNDERSTORMS DRIFTING ACROSS THE EASTERN HALF OF THE
COUNTRY.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST MODELS AND ENSEMBLES CONTINUE TO SHOW GOOD AGREEMENT ON
THE LARGE SCALE REGARDING THE INITIAL SOUTHERN TIER RIDGE SHIFTING
AND BUILDING OVER THE WEST. THE MAIN MODEL UNCERTAINTIES CONTINUE
TO LIE NORTH OF THE RIDGE, WITH THE TIMING AND STRENGTH OF A
SHORTWAVE THROUGH THE NORTHERN TIER INTO THE NORTHEAST. THE ECMWF
(AND THE UKMET) CONTINUE TO BE SLOWER WITH THIS FEATURE, EVEN AS
EARLY AS THURSDAY, WHILE THE CMC AND GFS ARE FASTER. THE ENSEMBLE
MEANS ARE WEAKER AND MORE IN THE MIDDLE, BUT THERE IS GOOD SUPPORT
FROM THE ECMWF-BASED AI/ML MODELS FOR THE FASTER SOLUTIONS BOOSTING
CONFIDENCE TO LEAN AWAY FROM THE OPERATIONAL ECMWF.
GUIDANCE AND ENSEMBLES CONTINUE TO HINT AT POSSIBLE TROPICAL
DEVELOPMENT INTO/TOWARDS THE GULF, WHICH THE LATEST OUTLOOK FROM
THE NATIONAL HURRICANE CENTER IS HIGHLIGHTING. THE OPERATIONAL
ECMWF AND ITS ENSEMBLES SHOW A MORE EASTERN TRACK (OWING TO
STRONGER RIDGING INTO THE GULF), BRINGING A LOW NORTHWARD OFF THE
COAST OF FL NEXT WEEKEND. THE CMC (WITH SOME SUPPORT FROM THE GEFS
AS WELL) SHOWS A MORE SOUTHERLY TRACK SOUTH OF FL INTO THE GULF. A
LOT OF UNCERTAINTY STILL ON THE TRACK OR EVEN ITS EXISTENCE AS A
DEFINED TROPICAL SYSTEM, BUT THIS FEATURE WILL NEED TO BE WATCHED.
THE WPC FORECAST LEANED MORE HEAVILY TOWARDS THE GFS/CMC EARLY IN
THE PERIOD, INCREASING THE WEIGHTING OF THE ENSEMBLE MEANS THURSDAY
ONWARD TO 60 PERCENT OF THE TOTAL BLEND BY DAY 7. OVERALL, THIS
MAINTAINED GOOD CONTINUITY WITH THE PREVIOUS WPC FORECAST THROUGH
SATURDAY.
..WEATHER/HAZARDS HIGHLIGHTS
A WET PATTERN IS LIKELY FROM THE MIDWEST TO THE EASTERN SEABOARD
NEXT WEEK WITH AMPLE MOISTURE AND INSTABILITY IN PLACE AS WELL AS
MEAN TROUGHING ALOFT AND SURFACE FRONTAL SYSTEMS FOR SCATTERED
THUNDERSTORMS. THUS THE DAYS 4-5 EXCESSIVE RAINFALL OUTLOOKS
COVERING WEDNESDAY-THURSDAY NIGHT SHOW FAIRLY BROAD MARGINAL RISKS
ACROSS PARTS OF THE MIDWEST TO THE NORTHEAST. MODEL GUIDANCE HAS
BEEN HINTING AT A LIKELY MESOSCALE CONVECTIVE SYSTEM WITH HEAVY
RAIN RATES MOVING ON THE CUSP OF THE INSTABILITY GRADIENT IN
NORTHWEST MEAN FLOW THAT SHOULD AFFECT PARTS OF THE MIDWEST
WEDNESDAY-WEDNESDAY NIGHT. THERE IS SOME PLACEMENT SPREAD WITH
THIS, BUT ANTECEDENT WET CONDITIONS AND THE HEAVY RAINFALL
POTENTIAL SEEMS TO WARRANT A DAY 5/WEDNESDAY SLIGHT RISK ACROSS THE
MIDWEST, THOUGH THE AREA WILL LIKELY BE ADJUSTED IN FUTURE
FORECASTS IF/WHEN MODELS CONVERGE. MUCH OF THE NORTH- CENTRAL U.S.
TO THE EASTERN THIRD OF THE COUNTRY SHOULD REMAIN GENERALLY
UNSETTLED THE REST OF THE WEEK AS A UPPER TROUGH IS SLOW TO BUDGE
OUT OF THE REGION WHILE IT GENERALLY WEAKENS.
ELSEWHERE, MONSOONAL CONVECTION OVER THE SOUTHWEST SHOULD STAY
CONFINED TO SOUTHERN AREAS THROUGH MIDWEEK, AND MARGINAL RISKS
REMAIN REASONABLE FOR THE DAYS 4-5 EROS. CHANCES FOR CONVECTION MAY
EXPAND NORTHEASTWARD INTO LATER WEEK DEPENDING ON THE SHAPE OF THE
SOUTHERN ROCKIES/PLAINS RIDGE AND UPPER LEVEL ENERGY ROTATING
AROUND ITS WESTERN PERIPHERY.
THE FORECAST PATTERN EVOLUTION WILL SUPPORT AN EXPANDING AREA OF
WARMER THAN AVERAGE TEMPERATURES ACROSS THE LOWER 48 INTO NEXT
WEEKEND. THE MOST SIGNIFICANT HIGH TEMPERATURE ANOMALIES SHOULD BE
OVER THE CENTRAL PLAINS EARLY ON WHERE SOME LOCATIONS SHOULD SEE
MULTIPLE DAYS WITH HIGHS 10-15F OR SO ABOVE NORMAL AND HIGH
TEMPERATURES NEAR 105F. THE EXPERIMENTAL HEATRISK LIKEWISE REFLECTS
AN EXPANDING AREA OF MAJOR TO EVEN EXTREME RISKS OF HEAT- RELATED
IMPACTS THROUGH NEXT WEDNESDAY. AN INCOMING FRONT WILL CAUSE SOME
EASING/SOUTHWARD SHIFT OF THE HEAT LATE NEXT WEEK IN THAT REGION,
WITH SOME HEAT BUILDING ACROSS PARTS OF THE SOUTHEAST AS WELL. MUCH
OF THE WEST WILL TREND WARMER AFTER WEDNESDAY, WITH LOWER
ELEVATIONS SEEING 100F+ HIGH TEMPERATURES. THE OHIO VALLEY TO EAST
COAST AND SOUTH TO THE GULF SHOULD ALSO TREND WARMER WITH TIME NEXT
WEEK.
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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