290
FXUS02 KWBC 251804
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
204 PM EDT FRI JUL 25 2025
VALID 12Z MON JUL 28 2025 - 12Z FRI AUG 01 2025
...SIGNIFICANT AND PERSISTENT HEAT WAVE CONTINUES ACROSS THE MID-
SOUTH AND SOUTHEAST THROUGH MUCH OF NEXT WEEK...
..OVERVIEW
A LARGE AND STRONG UPPER HIGH MEANDERING OVER THE CENTRAL/SOUTHERN
PLAINS INTO THE MID-SOUTH WILL CAUSE A PERSISTENT AND MAJOR HEAT
WAVE FOR THOSE AREAS THROUGH MUCH OF NEXT WEEK. DANGEROUS HEAT IS
FORECAST TO EXTEND NORTH THROUGH THE MIDWEST AND OHIO VALLEY EARLY
NEXT WEEK BUT GRADUALLY GET PRESSED SOUTHWARD BEHIND A COLD FRONT
AS THE WEEK PROGRESSES. COMPLEXES OF SHOWERS AND STORMS ARE LIKELY
ALONG THE NORTHERN PERIPHERY OF THE RIDGE, ACROSS THE
SOUTHERN/CENTRAL HIGH PLAINS EASTWARD INTO THE MIDWEST. SCATTERED
THUNDERSTORMS ARE POSSIBLE FARTHER EAST AT TIMES, ESPECIALLY NEAR
THE FRONT AS IT PUSHES SOUTH. ADDITIONALLY, SOUTHERLY FLOW WILL
BRING MONSOONAL MOISTURE INTO THE SOUTHWEST STATES FOR POSSIBLY
HEAVY RAIN.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL AGREEMENT REMAINS EXCELLENT FOR THE OVERALL PATTERN NEXT
WEEK. MODELS ARE UNIFIED IN SHOWING AN EXPANSIVE UPPER HIGH OF 2+
STANDARD DEVIATIONS ABOVE NORMAL, WITH WIDESPREAD 594+ DM 500MB
HEIGHTS BUT WITH LOWER CHANCES OF REACHING 600 DM. GUIDANCE SHOWS
THE HIGH MOST EXPANSIVE MONDAY-TUESDAY AS IT ENCOMPASSES THE SOUTH-
CENTRAL ROCKIES EAST ACROSS THE MISSISSIPPI AND OHIO VALLEYS AND
SOUTHEAST, BEFORE SHRINKING IN SCOPE AND BEING CENTERED MORE OVER
THE SOUTHERN PLAINS BY LATER NEXT WEEK. MEANWHILE THE RIDGE AXIS
WILL SHIFT WEST AND BUILD NORTH ACROSS THE NORTHERN ROCKIES INTO
WESTERN CANADA STARTING TUESDAY, CONTINUING TO SUPPORT AN OVERALL
BLOCKY/STAGNANT PATTERN OVER THE CONUS. AN UPPER TROUGH EDGING INTO
THE NORTH- CENTRAL TO NORTHEASTERN U.S. ANCHORED BY A LARGE HUDSON
BAY TO EASTERN CANADA UPPER LOW SHOWS GOOD AGREEMENT OVERALL BUT
SOME QUESTION ON HOW FAR SOUTH THE COLD FRONT REACHES BY THE END OF
THE WEEK.
REGARDLESS OF THE LARGE SCALE AGREEMENT, SHORTWAVES RIDING AROUND
THE RIDGE WILL CAUSE MORE DIFFERENCES IN SENSIBLE WEATHER LIKE
FRONTAL PLACEMENT, AND CONVECTION WILL HAVE FURTHER UNCERTAINTIES
DUE TO INTERACTING SMALLER SCALE BOUNDARIES. THESE MAY TAKE UNTIL
THE SHORT RANGE TO BECOME MORE CLEAR.
THE WPC FORECAST WAS INITIALLY BASED ON AN EQUAL BLEND OF THE 00Z
ECMWF, 06Z GFS, 00Z CMC, AND 00Z UKMET. USED SOME GEFS AND EC
ENSEMBLE MEANS BY THE LATTER PART OF THE PERIOD, BUT WAS ABLE TO
MAINTAIN A MAJORITY OF DETERMINISTIC GUIDANCE WITH THE GOOD GENERAL
AGREEMENT. THIS MAINTAINS GOOD AGREEMENT WITH THE PREVIOUS WPC
FORECAST AS WELL.
..WEATHER/HAZARDS HIGHLIGHTS
THE PERSISTENT AND STRONG UPPER RIDGE WILL LEAD TO CONTINUED
DANGEROUS HEAT THAT WILL BE LONGEST LASTING ACROSS THE TENNESSEE
VALLEY/MID-SOUTH AND SOUTHEAST INTO THE CAROLINAS NEXT WEEK.
HEATRISK IS IN THE MAJOR (LEVEL 3/4) TO EXTREME (LEVEL 4/4)
CATEGORIES FOR THESE AREAS THROUGH WEDNESDAY OR THURSDAY. HIGH
TEMPERATURES WILL BE IN THE UPPER 90S AND 100S WITH HEAT INDICES
POTENTIALLY EXCEEDING 110 TO 115 DEGREES, WHILE MORNING LOWS WELL
INTO THE 70S AND NEARING 80 WILL NOT PROVIDE MUCH RELIEF. THIS IS
LIKELY TO SET SCATTERED DAILY RECORDS FOR MAXIMUM TEMPERATURES AND
PERHAPS MORE WIDESPREAD RECORDS FOR MINIMUM TEMPERATURES. FARTHER
NORTH, THE MIDWEST AND OHIO VALLEY INTO THE MID-ATLANTIC CAN EXPECT
HOTTER THAN NORMAL TEMPERATURES INTO THE 90S WITH MAJOR HEATRISK
EARLY NEXT WEEK, BUT THESE AREAS ARE LIKELY TO COOL BY WEDNESDAY OR
THURSDAY BEHIND A COLD FRONT.
RAIN AND THUNDERSTORMS ARE LIKELY TO FOCUS ON THE PERIPHERY OF THE
RIDGE. SOME UPPER JET AND SHORTWAVE FORCING COMBINED WITH
SUFFICIENT MOISTURE AND HIGH TO EXTREME INSTABILITY SHOULD LEAD TO
CONVECTION ACROSS THE NORTHERN TIER MONDAY AND TUESDAY. THERE ARE
SOME UNCERTAINTIES IN THE AXIS OF STORMS AND PLACEMENT OF HEAVIEST
RAIN, SO WILL MAINTAIN MARGINAL RISKS IN THE DAY 4/MONDAY AND DAY
5/TUESDAY EXCESSIVE RAINFALL OUTLOOKS. ITS POSSIBLE THAT HEAVY RAIN
RATES AND RAIN AMOUNTS COULD EVENTUALLY WARRANT SLIGHT RISKS FOR
FLASH FLOODING. MEANWHILE TO THE WEST OF THE RIDGE, MONSOONAL
MOISTURE WILL BE INCREASING OVER THE SOUTHWEST. MARGINAL RISKS ARE
IN PLACE IN THE DAYS 4 AND 5 EROS FOR THE SOUTHWEST, AND REACHING
INTO THE CENTRAL ROCKIES/HIGH PLAINS ESPECIALLY BY DAY 5/TUESDAY AS
THE MONSOONAL MOISTURE MEETS THE FRONTAL SYSTEM TO THE NORTH. THE
NORTH-CENTRAL ROCKIES AND PLAINS LOOK TO BE AREAS OF FOCUS FOR
HEAVY RAIN INTO WEDNESDAY AND THURSDAY AS WELL.
ELSEWHERE, MOISTURE AND INSTABILITY COULD LEAD TO SCATTERED
THUNDERSTORMS IN PARTS OF THE EASTERN HALF OF THE U.S. FROM DAY TO
DAY. THERE MAY BE SOME FOCUS FOR STORMS ALONG THE COAST OF THE
CAROLINAS ON MONDAY, AND THEN OVER THE CENTRAL/EASTERN GULF COAST
ON TUESDAY AND WEDNESDAY ASSOCIATED WITH A TROUGH/WEAK LOW. DID GO
AHEAD AND ADD A MARGINAL RISK AREA FOR THE NORTHEAST GULF COAST
(NEAR THE FL BIG BEND AREA) FOR TUESDAY. BY WEDNESDAY AND
ESPECIALLY THURSDAY THE COLD FRONTS SLOWLY PUSHING SOUTH COULD
PROVIDE A FOCUS FOR ENHANCED RAIN AMOUNTS IN THE EAST, WHICH WILL
BE REFINED IN FUTURE FORECASTS.
SANTORELLI/TATE
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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