141
FXUS02 KWBC 310641
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
241 AM EDT WED JUL 31 2024
VALID 12Z SAT AUG 03 2024 - 12Z WED AUG 07 2024
...HAZARDOUS HEAT LIKELY THIS WEEKEND FOR PARTS OF THE WEST AND
SOUTHEAST, SHIFTING BACK INTO THE CENTRAL U.S. BY NEXT WEEK...
..OVERVIEW
AMPLIFIED UPPER RIDGING OVER THE WESTERN U.S. ON SATURDAY WILL
GRADUALLY GET SUPPRESSED WITH TIME AND EXPAND EASTWARD BACK INTO
PARTS OF THE SOUTH-CENTRAL U.S. AND THE SOUTHEAST. THIS WILL
PROMOTE HEAT THREATS SHIFTING FROM THE WEST INTO THE CENTRAL PLAINS
AND SOUTHEAST. NORTHERN STREAM FLOW AND ENERGY DIGGING TO THE LEE
OF THE UPPER RIDGE WILL REINFORCE TROUGHING OVER THE UPPER MIDWEST
TO NORTHEAST THAT LASTS INTO THE MIDDLE OF NEXT WEEK. THE NATIONAL
HURRICANE CENTER IS ALSO MONITORING THE POTENTIAL FOR TROPICAL
DEVELOPMENT THAT COULD AT LEAST COME CLOSE TO AFFECTING LOCATIONS
NEAR THE SOUTHEASTERN COAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
LATEST GUIDANCE AGREES FAIRLY WELL FOR THE LARGE SCALE PATTERN,
BUT STILL DISPLAYS IMPORTANT DIFFERENCES IN THE DETAILS. THERE IS
UNCERTAINTY REGARDING AMPLITUDE AND TIMING OF ENERGIES TO CARVE OUT
A MIDWEST/EASTERN U.S. MEAN UPPER TROUGH THIS WEEKEND INTO EARLY
NEXT WEEK BUT A GENERAL MODEL COMPROMISE SERVES AS A GOOD STARTING
POINT. THE RIDGE OVER THE WEST SHOULD BE SUFFICIENTLY STRONG TO
PREVENT ANY MAJOR INTRUSIONS FROM UPSTREAM, BUT GUIDANCE STRUGGLES
ON POSSIBLE ENERGY SLIDING INTO THE NORTHWEST AND OVER THE TOP OF
THE RIDGE ON SUNDAY WHICH COULD AFFECT ITS OVERALL
STRENGTH/NORTHWARD EXTENT BY EARLY NEXT WEEK.
MOST GUIDANCE CONTINUES TO SUPPORT THE IDEA OF POSSIBLE TROPICAL
DEVELOPMENT IN THE ATLANTIC, AS HIGHLIGHTED IN THE NATIONAL
HURRICANE CENTER OUTLOOK, BUT A LOT OF LINGERING UNCERTAINTY IN THE
EXACT TRACK. BETTER SUPPORT FOR A MORE EASTERLY TRACK UP THROUGH
THE BAHAMAS AND OFF THE SOUTHEAST U.S., AND LESS SO FOR SOMETHING
MORE WESTWARD INTO THE GULF. WPC FORECAST TODAY STUCK CLOSE TO THE
EASTERLY TRACK CONSISTENT WITH CONTINUITY AND NHC THOUGHTS.
THE WPC MEDIUM RANGE FORECAST SUITE WAS HEAVILY WEIGHTED TOWARDS
THE ECMWF AND ECENS MEAN. THIS WAS REASONABLE GIVEN GOOD AGREEMENT
IN THE REST OF THE GUIDANCE OVER THE MAJORITY OF THE CONUS AND THE
BEST SUPPORT FOR WPC/NHC PREFERENCES ON THE POTENTIAL TROPICAL
SYSTEM.
..WEATHER/HAZARDS HIGHLIGHTS
A GENERALLY WET AND UNSETTLED PATTERN IS LIKELY FROM THE OHIO
VALLEY TO THE EASTERN SEABOARD INTO THIS WEEKEND WITH AMPLE
MOISTURE AND INSTABILITY IN PLACE WHILE A SLOW MOVING UPPER TROUGH
AND SURFACE/FRONTAL SYSTEMS ALL SUPPORT AREAS OF SHOWERS AND
THUNDERSTORMS. THE DAYS 4 AND DAY 5 EXCESSIVE RAINFALL OUTLOOKS
CENTERED ON SATURDAY AND SUNDAY SHOW BROAD MARGINAL RISKS FROM THE
OHIO VALLEY/APPALACHIANS AND THE MID-ATLANTIC INTO THE NORTHEAST.
LATEST GUIDANCE CONTINUES TO SHOW POTENTIAL LOCALLY HEAVY RAINFALL
ACROSS PARTS OF THE ABOVE AREAS BUT THERE IS STILL A LOT OF SPREAD
FOR LOCATION OF HEAVIEST ACTIVITY, PLUS DEPENDENCE ON STILL
UNCERTAIN SHORTER TERM RAINFALL AND RESULTING SOIL SENSITIVITY.
PARTS OF THE NORTH- CENTRAL U.S. TO THE EASTERN THIRD OF THE
COUNTRY SHOULD REMAIN GENERALLY UNSETTLED INTO EARLY NEXT WEEK WITH
GENERAL MEAN TROUGHING LIKELY TO PERSIST. LOCATIONS NEAR FLORIDA
AND THE SOUTHEASTERN COAST SHOULD MONITOR LATEST FORECASTS
REGARDING POSSIBLE TROPICAL DEVELOPMENT DURING THE WEEKEND/EARLY
NEXT WEEK TIME FRAME. A DAY 4/SATURDAY MARGINAL RISK AREA WAS
MAINTAINED FOR SOUTHEAST FLORIDA TO DENOTE THE UNCERTAIN RAINFALL
THREAT GIVEN PROXIMITY.
ELSEWHERE, MONSOONAL CONVECTION OVER THE SOUTHWEST CONTINUES TO
SUPPORT MARGINAL RISK AREAS ON THE DAYS 4 AND 5 EROS. CHANCES FOR
CONVECTION MAY EXPAND NORTHWARD WITH TIME DEPENDING ON THE SHAPE OF
THE SOUTHERN ROCKIES/PLAINS RIDGE AND UPPER LEVEL ENERGY ROTATING
AROUND ITS PERIPHERY.
HEAT SHOULD REMAIN A THREAT ACROSS PARTS OF THE WEST INTO NEXT
WEEK, WITH LOWER ELEVATIONS SEEING NEAR 100F HIGH TEMPERATURES MOST
DAYS. SCATTERED RECORD HIGHS AND RECORD HIGH MIN TEMPS ARE
POSSIBLE ON SATURDAY AS WELL. ABOVE NORMAL TEMPERATURES FROM THE
NORTHERN PLAINS TO THE NORTHEAST INTO SATURDAY SHOULD MODERATE AND
SHIFT SOUTH AS SHORTWAVE ENERGY MOVES THROUGH THESE REGIONS. AS THE
UPPER RIDGE BUILDS BACK EASTWARD NEXT WEEK, HAZARDOUS HEAT WILL
RETURN TO PARTS OF THE CENTRAL/SOUTHERN PLAINS TO THE SOUTHEAST.
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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