545
FXUS02 KWBC 290619
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
219 AM EDT MON JUL 29 2024
VALID 12Z THU AUG 01 2024 - 12Z MON AUG 05 2024
...HAZARDOUS HEAT TO SHIFT FROM THE SOUTH-CENTRAL PLAINS EARLY
PERIOD TO THE NORTHWEST LATER THIS WEEK...
..OVERVIEW
A STRONG UPPER RIDGE OVER THE CENTRAL U.S. INTO THE SOUTHEAST AS
THE PERIOD BEGINS THURSDAY WILL CONTINUE TO PROMOTE UNSEASONABLY
WARM TEMPERATURES OVER CENTRAL PARTS OF THE PLAINS AND INTO THE
SOUTHEAST. A SHORTWAVE THROUGH THE NORTHERN TIER WILL EVENTUALLY
ESTABLISH TROUGHING IN THE EAST, ALLOWING FOR THE RIDGE TO SHIFT
MORE INTO THE WEST. THIS SETS UP WHAT COULD BE A RATHER STAGNANT
UPPER PATTERN INTO EARLY NEXT WEEK SUPPORTING INCREASING HEAT
ACROSS THE WEST, AND UNSETTLED WEATHER OVER THE EAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST MODELS AND ENSEMBLES CONTINUE TO SHOW GOOD AGREEMENT ON
THE LARGE SCALE PATTERN EVOLUTION, BUT PLENTY OF UNCERTAINTY IN
THE DETAILS. THE MAIN SYSTEM OF UNCERTAINTY IS STILL WITH THE
SHORTWAVE THROUGH THE MIDWEST ON THURSDAY, LEADING TO MEAN
TROUGHING OVER THE EAST BY THE WEEKEND. COMPARED TO A DAY AGO,
MODELS SEEM TO BE CONVERGING ON A LITTLE SLOWER SOLUTION, BUT THE
GFS IS STILL NOTABLY FASTER THAN THE CONSENSUS, THOUGH STILL WITH
SUPPORT FROM SOME OF THE AI/ML MODELS. MODELS ARE STILL QUITE
UNCERTAIN WITH THE PATTERN IN THE NORTHEASTERN PACIFIC, WHICH COULD
AFFECT THE NORTHWEST AS WELL.
STILL SEEING SUPPORT FOR POSSIBLE TROPICAL DEVELOPMENT IN THE
ATLANTIC, WHICH THE LATEST OUTLOOK FROM THE NATIONAL HURRICANE
CENTER IS HIGHLIGHTING. THE OPERATIONAL ECMWF AND ITS ENSEMBLES
SHOW A MORE EASTERN TRACK, BRINGING A LOW NORTHWARD OFF THE COAST
OF FL/THE SOUTHEAST NEXT WEEKEND. THE CMC IS SIGNIFICANTLY STRONGER
AND SHOWS A MORE SOUTHERLY TRACK SOUTH OF FL INTO THE GULF. A LOOK
AT ENSEMBLE LOW PLOTS FROM THE ECENS AND GEFS ILLUSTRATE THE
UNCERTAINTY ON THE TRACK OR EVEN ITS EXISTENCE AS A DEFINED
TROPICAL SYSTEM, BUT THIS FEATURE WILL NEED TO BE WATCHED.
THE WPC FORECAST USED A BLEND OF DETERMINISTIC GUIDANCE EARLY IN
THE PERIOD, WITH MORE ENSEMBLE MEAN SUPPORT LATE PERIOD (WITH
CONTINUED WEIGHTING TOWARDS THE ECMWF). OVERALL, THIS MAINTAINED
GOOD CONTINUITY WITH THE PREVIOUS WPC FORECAST.
..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 ALL SUPPORTING
SCATTERED THUNDERSTORMS. THUS THE DAYS 4-5 EXCESSIVE RAINFALL
OUTLOOKS COVERING THURSDAY-FRIDAY NIGHT SHOW FAIRLY BROAD MARGINAL
RISKS ACROSS PARTS OF THE MIDWEST TO OHIO VALLEY AND THE
NORTHEAST/MID-ATLANTIC. SOME POTENTIAL FOR MESOSCALE SYSTEMS WITH
HEAVY RAINFALL TO MOVE THROUGH THE REGION, BUT WAY TOO MUCH
UNCERTAINTY FOR ANY SORT OF SLIGHTS ON THE EROS STILL. MUCH OF THE
NORTH- CENTRAL U.S. TO THE EASTERN THIRD OF THE COUNTRY SHOULD
REMAIN GENERALLY UNSETTLED THROUGH NEXT WEEKEND AND INTO EARLY NEXT
WEEK AS THE NOW ESTABLISHED UPPER TROUGH IS SLOW TO BUDGE OUT OF
THE REGION.
ELSEWHERE, MONSOONAL CONVECTION OVER THE SOUTHWEST CONTINUES TO
SUPPORT MARGINAL RISKS ON THE DAYS 4 AND 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. AS SUCH THE DAY
5/THURSDAY MARGINAL EXPANDS A BIT NORTHWARD INTO SOUTHERN COLORADO,
AND RAIN CHANCES INCREASE INTO THE CENTRAL HIGH PLAINS BY FRIDAY.
THE HEAT WAVE OVER THE CENTRAL PLAINS EARLY THIS WEEK SHOULD
CONTINUE THROUGH THURSDAY, WITH DAYTIME HIGHS AROUND 10F ABOVE
NORMAL AND WIDESPREAD MAJOR TO LOCALLY EXTREME HEATRISK THREATS. AN
INCOMING FRONT WILL BRING RELIEF TO THE CENTRAL PLAINS BY FRIDAY,
BUT HEAT WILL CONTINUE ACROSS THE SOUTHEAST THROUGH FRIDAY WITH
WARM OVERNIGHT TEMPERATURES ONLY EXACERBATING HEAT STRESS IN THAT
REGION. MEANWHILE, MUCH OF THE WEST WILL TREND WARMER, WITH LOWER
ELEVATIONS SEEING 100F+ HIGH TEMPERATURES. SCATTERED DAILY RECORD
HIGHS ARE POSSIBLE. SHORTER BURSTS OF ABOVE NORMAL TEMPERATURES ARE
ALSO LIKELY FOR THE MIDWEST TO OHIO VALLEY TO THE MID-
ATLANTIC/NORTHEAST LATE THIS WEEK, WITH PERHAPS SOME MODERATION
NEXT WEEKEND AFTER COLD FRONTS PASS THROUGH.
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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