368
FXUS02 KWBC 311850
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
250 PM 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, WORKING BACK INTO THE SOUTH-CENTRAL U.S. 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.. 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 THE EAST
THAT LASTS THROUGH THE MIDDLE OF NEXT WEEK. THE NATIONAL HURRICANE
CENTER IS ALSO MONITORING THE POTENTIAL FOR TROPICAL DEVELOPMENT
THAT COULD AFFECT THE SOUTHEAST FROM THE WEEKEND INTO NEXT WEEK.
..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 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. THERE REMAINS QUITE A BIT OF UNCERTAINTY, BUT THERE IS
STILL 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 TRENDED CLOSER TO THE
EASTERLY TRACK CONSISTENT WITH CONTINUITY AND NHC THOUGHTS.
THE WPC MEDIUM RANGE FORECAST SUITE WAS HEAVILY WEIGHTED TOWARDS
THE 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.
THIS SOLUTION DISCOUNTED MUCH MORE INUNDATING MODEL QPF SOLUTIONS
OUT FROM THE GULF AND POSSIBLE SLOWED POTENTIAL SYSTEM FORWARD
SPEED OVER TIME. HOWEVER, A MORE WESTWARD TRACK TO THE GULF IS
PLAUSIBLE AS OVERALL SUPPORTED BY LATEST 12 UTC GUIDANCE TRENDS.
..WEATHER/HAZARDS HIGHLIGHTS
IT OVERALL REMAINS THE CASE THAT A GENERALLY WET AND UNSETTLED
PATTERN IS LIKELY FROM THE UPPER 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. DAY 4/SATURDAY AND
DAY 5/SUNDAY MARGINAL RISK AREAS FOR SOUTHEAST FLORIDA PORTEND THE
UNCERTAIN RAINFALL THREAT GIVEN POTENTIAL TROPICAL SYSTEM 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/SCHICHTEL
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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