112
FXUS02 KWBC 041820
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
220 PM EDT SAT JUL 4 2026
VALID 12Z TUE JUL 07 2026 - 12Z SAT JUL 11 2026
..MAJOR HEATWAVE TO SETTLE OVER THE SOUTHERN TIER NEXT WEEK
..PATTERN OVERVIEW
BROAD UPPER-LEVEL RIDGING IS FORECAST TO BUILD OVER THE SOUTHERN
U.S. NEXT WEEK WHILE TRANSIENT SHORTWAVES PROPAGATE THROUGH THE
GREAT LAKES AND NORTHEAST/MID-ATLANTIC. THE SOUTHERN RIDGE WILL
SUPPORT A MAJOR HEATWAVE INITIALLY OVER THE SOUTH/SOUTHEAST THEN
BUILDING INTO THE SOUTHWEST/GREAT BASIN. TROUGHING ALONG THE
U.S.-CANADIAN BORDER WILL PROMOTE DIURNAL SHOWERS AND THUNDERSTORMS
FROM THE NORTHERN PLAINS TO THE NORTHEAST, WITH A FOCUSED RISK FOR
HEAVIER RAIN OVER THE UPPER MIDWEST INTO THE GREAT LAKES TUE-WED.
TROUGHING OVER THE NORTHEAST PACIFIC WILL MAINTAIN NEAR TO BELOW
AVERAGE TEMPERATURES IN THE PACIFIC NORTHWEST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS AND ENSEMBLES WERE IN MOSTLY GOOD AGREEMENT REGARDING THE
EVOLUTION OF THE SYNOPTIC PATTERN NEXT WEEK. THERE WAS A BUDGE
FASTER IN THE NORTHERN STREAM FLOW COMPARED TO THE PREVIOUS
FORECAST, BUT OVERALL CONTINUITY WAS GOOD. DIFFERENCES AMONG THE
DETERMINISTIC MODELS GENERALLY FELL WITHIN THE TYPICAL RANGE FOR
MID-SUMMER.
..WEATHER/HAZARDS HIGHLIGHTS
A MAJOR HEATWAVE WILL ENSUE ACROSS THE SOUTH/SOUTHEAST AND
SOUTHWEST NEXT WEEK AS WEAK UPPER RIDGING/QUASI-ZONAL FLOW IS
EXPECTED TO PERSIST SOUTH OF TRANSIENT SHORTWAVES PROPAGATING
THROUGH THE NORTHEAST/MID-ATLANTIC. THE AFOREMENTIONED TROUGHING
WILL PULL WARM AND MOIST AIR ACROSS THE SOUTHEAST AND GENERATE
DAILY HEAT INDICES BETWEEN 105-110 DEGREES FROM EASTERN TEXAS TO
THE MID-ATLANTIC/SOUTHEAST COAST NEXT WEEK. THESE CONDITIONS WILL
BE DANGEROUS AND LIKELY IMPACT SOME HEALTH SYSTEMS, HEAT SENSITIVE
INDUSTRIES, AND INFRASTRUCTURE. THIS LEVEL OF HEAT WILL ALSO AFFECT
THOSE WITHOUT ADEQUATE COOLING AND/OR HYDRATION.
SURFACE WAVES AND ATTENDANT FRONTS DRAPED ACROSS THE NORTHERN
PLAINS AND UPPER MIDWEST WILL BE THE FOCUS FOR SCATTERED
THUNDERSTORMS ON TUESDAY AND WEDNESDAY. WELL ABOVE NORMAL MOISTURE
(>90TH PERCENTILE) AND INSTABILITY ALONG THE FRONT COULD COMBINE TO
PRODUCE HEAVY RAINFALL/FLASH FLOODING, BUT WEAK SHEARING WILL
LIKELY MITIGATE A SEVERE WEATHER THREAT. RAIN SHOWERS AND
THUNDERSTORMS WILL MOVE INTO THE EASTERN U.S. LATER IN THE WEEK
INTO NEXT WEEKEND. LASTLY, MONSOONAL MOISTURE MAY START TO INCREASE
OVER AT LEAST ARIZONA LATE NEXT WEEK INTO THE WEEKEND AS THE UPPER
HIGH DRIFTS A BIT FARTHER NORTH INTO UTAH.
FRACASSO/KEBEDE
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, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY MESSAGES
ARE AT:
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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