034
FXUS02 KWBC 120730
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
330 AM EDT SUN JUL 12 2026
VALID 12Z WED JUL 15 2026 - 12Z SUN JUL 19 2026
...DANGEROUS HEAT CONTINUES ACROSS THE NORTH-CENTRAL U.S. THROUGH
NEXT WEEKEND AND SPREAD TO THE EAST AT TIMES..
..OVERVIEW
AN ELONGATED AND ANOMALOUSLY STRONG UPPER-LEVEL RIDGE WILL STRETCH
FROM THE INTERMOUNTAIN WEST THROUGH MIDWEST TOWARD THE MID-
ATLANTIC MIDWEEK, WITH THE EASTERN PORTION JOINING UP WITH A
SUBTROPICAL ATLANTIC RIDGE AND THE WESTERN PORTION RETROGRADING A
BIT INTO LATE WEEK AND NEXT WEEKEND. HAZARDOUS HEAT IS LIKELY TO
CONTINUE UNDER THE RIDGE, AND MAJOR TO EXTREME HEATRISK WILL BE
PERSISTENT ACROSS THE DAKOTAS TO MIDWEST. RAIN AND THUNDERSTORMS
ARE LIKELY ON THE SOUTHERN PERIPHERY OF THE RIDGE, WITH ELEVATED
CHANCES OF HEAVY RAIN AND FLASH FLOODING IN WESTERN/CENTRAL TEXAS
IN PARTICULAR. ADDITIONALLY, MONSOONAL MOISTURE IS FORECAST TO
INCREASE AND PRODUCE SHOWERS AND STORMS ACROSS THE SOUTHWEST, FOUR
CORNERS STATES, AND NORTHWARD INTO THE NORTHERN ROCKIES/HIGH
PLAINS. SOME ENERGIES ON THE NORTHERN SIDE OF THE RIDGE COULD ALSO
LEAD TO ROUNDS OF RAIN AND THUNDERSTORMS IN THE NORTHERN TIER,
INCLUDING A SEVERE THREAT OVER THE MID-ATLANTIC FRIDAY WITHIN A
RENEWED PRE-FRONTAL EAST COAST HEAT THREAT.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE SHOWS GOOD AGREEMENT IN TERMS OF THE 594+ DM UPPER
HIGH CENTERED NEAR THE NORTH-CENTRAL U.S. AND MEANDERING THROUGH
THE WEEK, LEADING TO HIGH CONFIDENCE IN MULTIPLE DAYS OF HAZARDOUS
HEAT. MODELS INDICATE THE RIDGE SHOULD STRETCH INTO THE MID-
ATLANTIC MIDWEEK AND GET GRADUALLY SUPPRESSED BY AN UPPER TROUGH
MOVING INTO THE NORTHEAST BY THE LATTER HALF OF THE WEEK. THIS
EASTERN PART OF THE RIDGE MAY JOIN WITH THE SUBTROPICAL ATLANTIC
HIGH THAT SHIFTS WEST THROUGH LATER WEEK. MEANWHILE FARTHER WEST,
THE RIDGE SHOULD GET RENEWED ACROSS THE NORTHERN/CENTRAL ROCKIES
AND PLAINS.
SMALLER-SCALE ENERGIES TO THE SOUTH OF THE RIDGE ARE RELATIVELY
MORE UNCERTAIN, BUT GUIDANCE CONTINUES TO HIGHLIGHT A NOTABLE
SHORTWAVE OVER THE SOUTHERN HIGH PLAINS WEDNESDAY-THURSDAY BRINGING
ENHANCED QPF. MEANWHILE A NORTHEASTERN PACIFIC UPPER LOW HAS SHOWN
THE MOST NOTABLE VARIATIONS IN THE GUIDANCE OVER THE PAST DAY OR
TWO. THE NEW 00Z MODEL CYCLE DOES SHOW A BETTER CONSENSUS, AS THE
00Z ECMWF HAS A SLOWER/FARTHER WEST TRACK THAN ITS 12Z RUN AND
BETTER MATCHES THE REMAINDER OF THE GUIDANCE THROUGH THURSDAY. THE
TRACK REMAINS UNCERTAIN INTO LATE WEEK THOUGH, AND WHILE THERE IS A
GENERAL SIGNAL FOR A SHORTWAVE TO MOVE FROM CENTRAL CANADA INTO
THE GREAT LAKES AROUND SATURDAY, THIS TIMING AND TRACK REMAINS
RATHER QUESTIONABLE TOO.
THE WPC FORECAST WAS BASED ON A MULTI-MODEL DETERMINISTIC BLEND
EARLY ON, WITH INCREASING PROPORTIONS OF THE ENSEMBLE MEANS TO
ABOUT HALF THE BLEND BY DAY 7 AMID INCREASING SPREAD.
..WEATHER/HAZARDS HIGHLIGHTS
THE STRONG AND EXPANSIVE UPPER RIDGE WILL CONTINUE TO CREATE
CONCERNS FOR HAZARDOUS HEAT ACROSS THE NORTHERN PLAINS TO MIDWEST
THROUGH MIDWEEK AND CONTINUING INTO THE WEEKEND, WITH SOME DAY TO
DAY VARIATIONS IN THE PLACEMENT. SEVERAL DAYS OF WELL ABOVE NORMAL
AND POTENTIALLY RECORD-BREAKING MAXIMUM AND MINIMUM TEMPERATURES
WILL LEAD TO MAJOR TO EXTREME HEATRISK. WPC CONTINUES TO UPDATE
HEAT KEY MESSAGES FOR THIS EVENT, WHICH CAN BE FOUND ON OUR
HOMEPAGE. FARTHER EAST, WARMER THAN AVERAGE TEMPERATURES ARE LIKELY
FOR THE GREAT LAKES AND NORTHEAST TO MID-ATLANTIC INTO WEDNESDAY,
BUT SHIFT GRADUALLY SOUTHWARD AS AN UPPER TROUGH PUSHES A COLD
FRONT SLOWLY SOUTH. THE UPPER RIDGE POTENTIALLY COMBINING WITH
SUBTROPICAL RIDGING DOWN TO FLORIDA WILL MAINTAIN WARM TEMPERATURES
AND ELEVATED HEATRISK THERE.
MEANWHILE, MUCH OF THE SOUTHERN TIER COULD SEE NEAR TO SLIGHTLY
BELOW AVERAGE TEMPERATURES AS AMPLE MOISTURE LEADS TO CLOUDS AND
RAIN/THUNDERSTORMS. INCREASING SOUTHERLY FLOW AROUND THE WESTERN
PERIPHERY OF THE CENTRAL U.S. RIDGE WILL DRAW SIGNIFICANT MONSOONAL
MOISTURE INTO THE SOUTHWEST AND INTERMOUNTAIN WEST TO ROCKIES.
THIS MOISTURE WILL LEAD TO SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS WITH THE 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 RISKS OF EXCESSIVE
RAINFALL REMAIN IN PLACE FROM THE SOUTHWEST NORTH TO MONTANA FOR
DAY 4-5 (WEDNESDAY-THURSDAY), AND MONSOONAL MOISTURE SHOULD
CONTINUE INTO NEXT WEEKEND. FARTHER EAST, PACIFIC AND GULF MOISTURE
SHOULD COMBINE IN THE VICINITY OF A SHORTWAVE ALOFT OVER TEXAS,
LEADING TO FURTHER FLOODING CONCERNS. SLIGHT RISKS ARE IN PLACE FOR
WESTERN/SOUTH-CENTRAL PORTIONS OF TEXAS INTO WEDNESDAY AND
THURSDAY, AND THE FLOODING THREAT COULD BE COMPOUNDED BY THE LIKELY
RAINFALL IN THE SHORT RANGE PERIOD CAUSING WETTER ANTECEDENT
CONDITIONS. SOME SHOWERS AND STORMS COULD STRETCH INTO THE
SOUTHEAST. ROUNDS OF RAIN/THUNDERSTORMS ARE ALSO POSSIBLE FARTHER
NORTH FROM THE GREAT LAKES TO THE MID-ATLANTIC AND NORTHEAST LATE
WEEK AS ENERGY MOVES THROUGH THE NORTHEASTERN UPPER TROUGH. THE
STORM PREDICTION CENTER HAS DELINEATED A SEVERE THREAT IN THE MID-
ATLANTIC TO MONITOR FOR FRIDAY.
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, 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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