030
FXUS02 KWBC 181725
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
125 PM EDT SAT JUL 18 2026
VALID 12Z TUE JUL 21 2026 - 12Z SAT JUL 25 2026
..HAZARDOUS HEAT TO SETTLE DOWN ACROSS THE SOUTH NEXT WEEK
..OVERVIEW
VERY HOT AND MOIST CONDITIONS WILL FOCUS OVER THE SOUTH NEXT WEEK
AS NORTHERN TIER SHORTWAVES AND MODERATING SURFACE FRONTS FOCUS
ROUNDS OF LOCALLY HEAVY RAINS AND STRONG TO SEVERE THUNDERSTORMS
FROM THE MIDWEST/GREAT LAKES TO THE EAST. LEAD ACTIVITY OVER THE
SOUTH/SOUTHEAST MAY BE FUELED BY GULF/TROPICAL MOISTURE. ELSEWHERE,
AMPLE MONSOONAL MOISTURE WILL CONTINUE TO STREAM FROM THE
SOUTHWEST AND INTERMOUNTAIN WEST/ROCKIES AND THEN THE PLAINS TO
FUEL ENHANCED SHOWERS AND THUNDERSTORMS AS A CLOSED UPPER HIGH
SHIFTS TO THE SOUTHERN PLAINS. MEANWHILE, CURRENT TROPICAL STORM
ELIDA IS FORECAST BY NHC TO WEAKEN INTO NEXT WEEK WHILE LIFTING
NORTHWARD WELL OFF THE WEST COAST NEAR 130W AS A MARITIME THREAT.
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE REMAINS IN GENERALLY GOOD AGREEMENT THROUGH THE EARLY
PORTION OF THE PERIOD, WITH DETERMINISTIC SOLUTIONS FROM THE GFS,
ECMWF, AND CMC DEPICTING A BROADLY SIMILAR LARGE-SCALE SYNOPTIC
PATTERN OF A RIDGE BUILDING OVER THE WEST AND SOUTH AND A TROUGHING
OVER THE EAST. THE MODELS ALSO CAPTURE THE SHORTWAVE ENERGY
PROGRESSING THROUGH THE NORTHERN TIER AND SOUTHERN CANADA, WITH
SOME MINOR DIFFERENCES WITH TIMING AND AMPLITUDE. DIFFERENCES BEGIN
TOWARDS MID TO LATE WEEK, WHERE THE AMPLITUDE, TIMING, AND PHASING
OF SHORTWAVES EMBEDDED WITHIN THE NORTHERN STREAM BECOME LARGER.
ADDITIONALLY, MODELS DIVERGE WITH THE DEEPENING OF THE TROUGH OVER
THE EASTERN U.S. AND OVER PACIFIC NORTHWEST, SPECIFICALLY WITH THE
ECMWF. THESE DIFFERENCES TRANSLATE INTO FRONTAL PLACEMENT ACROSS
CENTRAL AND EASTERN U.S., WHICH CAN IMPACT PRECIPITATION TIMING
AND MAGNITUDE. THE ENSEMBLE MEANS SEEMS TO SMOOTH SOME OF THESE
DIFFERENCES A BIT, ESPECIALLY AFTER WEDNESDAY. THEREFORE, THE
FORECAST FAVORED A MULTI-MODEL BLEND FOR THE FIRST PORTION OF THE
PERIOD, WITH PHASING IN THE ENSEMBLE MEANS TOWARDS THE LATTER
PORTION OF THE PERIOD.
..WEATHER/HAZARDS HIGHLIGHTS
FLOW AROUND A MAIN UPPER RIDGE WILL CONTINUE TO DRAW SIGNIFICANT
MONSOONAL MOISTURE INTO THE SOUTHWEST AND INTERMOUNTAIN
WEST/ROCKIES INTO NEXT WEEK. THIS MOISTURE WILL LEAD TO SCATTERED
TO NUMEROUS SHOWERS AND THUNDERSTORMS WITH POTENTIAL TO PRODUCE
HEAVY RAINFALL AND LOCALIZED FLASH FLOODING. SENSITIVE PLACES SUCH
AS BURN SCARS, STEEP TERRAIN, ETC., WOULD BE THE MOST VULNERABLE TO
ANY FLOODING CONCERNS THAT MAY DEVELOP. BROAD MARGINAL AND AN
EMBEDDED SLIGHT RISK OF EXCESSIVE RAINFALL HAVE BEEN INTRODUCED
FROM THE SOUTHWEST INTO THE INTERMOUNTAIN WEST FOR TUESDAY INTO
WEDNESDAY. SHOWER AND THUNDERSTORM COVERAGE SHOULD GRADUALLY
INCREASE EASTWARD FROM THE ROCKIES INTO THE PLAINS NEXT WEEK AS THE
CLOSED UPPER HIGH SHIFTS DOWN TO THE SOUTHERN PLAINS.
UPPER RIDGE/CLOSED HIGH INFLUENCE SHIFT TO THE SOUTH WILL LEAD TO
AT LEAST MAJOR HEATRISKS OVER MUCH OF THE SOUTH NEXT WEEK AS
TEMPERATURES 5-10F ABOVE ALREADY HOT AVERAGES COMBINE WITH HIGH
HUMIDITY. EXPECT SPOTTY RECORD HIGHS AND MORE WIDESPREAD RECORD
OVERNIGHT LOWS. HEAT INDICES MAY RISE TO 105-110+F IN SOME SPOTS.
ELSEWHERE, HEAVY RAINS WITH STRONG TO SEVERE THUNDERSTORMS PER SPC
ARE FORECAST TO WORK THROUGH THE MIDWEST/GREAT LAKES INTO EARLY
NEXT WEEK GIVEN SHORTWAVES ALOFT AND WAVY FRONTAL PUSH. AS THE
UPPER TROUGH POSITION AMPLIFIES AND THE FRONTS WORK SOUTHEAST
THROUGH EARLY-MID NEXT WEEK, HEAVY CONVECTIVE RAIN CHANCES WILL
OVERSPREAD MUCH OF THE EAST, SETTLING INTO THE SOUTHEAST LATER NEXT
WEEK WITH SLOW WAVY FRONTAL PROGRESSION. WPC EXCESSIVE RAINFALL
MARGINAL RISK AREAS SLOWLY SHIFT EASTWARD TUESDAY AND WEDNESDAY
FROM THE OHIO VALLEY TO OVER THE MID-ATLANTIC AND THE NORTHEAST.
AN EMBEDDED SLIGHT RISK AREA HAS ALSO BEEN INTRODUCED FOR TUESDAY
OVER THE CENTRAL APPALACHIANS.
MEANWHILE TO THE SOUTH, ENERGY IS FORECAST TO MEANDER FROM THE
NORTHEASTERN GULF IN A MOIST AND UNSTABLE ENVIRONMENT INTO EARLY
NEXT WEEK AS MONITORED BY NHC. TROUGHING AND TROPICAL MOISTURE IN
PLACE (EVEN IF THERE IS NO TRUE TROPICAL LOW) MAY LEAD TO HEAVY
RAIN AND MARGINAL RISKS ARE FROM NORTHERN FLORIDA TO THE COASTAL
SOUTHEAST FOR ISOLATED FLASH FLOODING FOR TUESDAY INTO WEDNESDAY.
THERE IS SOME GUIDANCE SIGNAL TO MONITOR THAT A COMBINATION OF
SYSTEM ENERGIES FROM THE NORTH AND DEEPER GULF/TROPICAL MOISTURE
MAY FAVOR LINGERING HEAVY RAIN FRONTAL FOCUS EXTENDING INTO LATER
NEXT WEEK OVER THE EASTERN CAROLINAS VERSUS A SHIFT JUST OFFSHORE.
OUDIT/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, 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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