000
FXUS02 KWBC 311908
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
308 PM EDT THU JUL 31 2025
VALID 12Z SUN AUG 03 2025 - 12Z THU AUG 07 2025
..OVERVIEW
BROAD UPPER TROUGHING WITH A LARGE POOL OF COOL AIR THAT HAS
SETTLED INTO EASTERN U.S. BY THIS WEEKEND WILL BE REINFORCED BY
DISTURBANCES DROPPING SOUTHEAST ACROSS THE PLAINS ON THE EASTERN
EDGE OF AN UPPER RIDGE OVER THE SOUTHWEST WHICH IS FORECAST TO
BUILD AND EXPAND BY THE MIDDLE OF NEXT WEEK. A STALLED FRONT WILL
INITIALLY SUPPORT HEAVY RAIN THREAT MAINLY NEAR THE COASTAL
SECTIONS OF THE SOUTHEAST. BUT AS THE BERMUDA HIGH BEGINS TO BUILD
WESTWARD, WET WEATHER IS FORECAST TO SPREAD NORTHWARD UP THE
EASTERN U.S. THROUGH MIDWEEK. MEANWHILE, UPPER TROUGHING IS
FORECAST TO PUSH THROUGH THE NORTHWEST WITH PACIFIC FRONTS FORECAST
TO MOVE INTO THE NORTHERN PLAINS BY MIDWEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE REMAINS IN GOOD AGREEMENT ON THE OVERALL SYNOPTIC
PATTERN EVOLUTION ACROSS THE U.S. THROUGH THE MEDIUM-RANGE PERIOD,
WITH RELATIVELY MINOR DIFFERENCES IN DETAILS EARLY IN THE PERIOD.
DIFFERENCES BECOME MORE NOTICEABLE LATER IN THE PERIOD, WITH THE
GFS/GEFS CLUSTER SUPPORTS A MORE NORTHWARD EXTENSION OF THE
RAINFALL UP FROM THE SOUTHEAST TOWARD THE TENNESSEE VALLEY AHEAD
OF THE UPPER TROUGH REINFORCEMENTS ARRIVING FROM THE PLAINS. IN
ADDITION, MODEL CONSENSUS NOW BETTER SUPPORT FRONTAL WAVE
DEVELOPMENT NEAR THE CAROLINA COASTS WITH RAINFALL SPREADING
FARTHER NORTH UP THE EAST COAST DURING MIDWEEK NEXT WEEK. OVER THE
SOUTH-CENTRAL U.S., THE EC/EC MEAN CLUSTER CONTINUES TO FAVOR A
FARTHER SOUTH-AND-WEST PLACEMENT OF THE QPF MAX. SUNDAY AND MONDAY
WHEN COMPARED WITH THE GFS/GEFS CLUSTER. OTHERWISE, DIFFERENCES
ARE RELATIVELY MINOR FOR THE REMAINDER OF THE U.S. COMPARED WITH
THE PREVIOUS WPC FORECAST PACKAGE.
..WEATHER/HAZARDS HIGHLIGHTS
A RATHER EXPANSIVE AND COOL AIR MASS IS FORECAST TO SETTLE INTO
THE EASTERN U.S. AS THE MEDIUM-RANGE PERIOD BEGINS EARLY AUGUST.
HIGH MOISTURE CONTENT AND INSTABILITY NEAR THE FRONT WILL ALLOW FOR
SOME LOCALIZED HEAVY RAIN, WHICH WOULD RAISE FLASH FLOODING RISK
ESPECIALLY AFTER RAIN FROM THE PREVIOUS DAY OR TWO COULD MAKE
ANTECEDENT CONDITIONS WETTER. A SLIGHT RISK OF EXCESSIVE RAINFALL
HAS BEEN INTRODUCED NEAR COASTAL GEORGIA WHERE THERE IS BEST
MODEL CONSENSUS FOR MOIST EASTERLY FLOW FROM THE ATLANTIC TO
CONVERGE WITHIN A MARGINAL RISK ACROSS NORTHERN FLORIDA INTO
SOUTHEASTERN ALABAMA AND NEAR THE SOUTH CAROLINA COAST ON DAY
4/SUNDAY. THE MARGINAL RISK IS MAINTAINED INTO DAY 5/MONDAY AS THE
FRONT STALLS INTO THE WORKWEEK.
FARTHER WEST, SHORTWAVES ROUNDING THE EASTERN EDGE OF THE UPPER
RIDGE IN THE ROCKIES/HIGH PLAINS ARE FORECAST TO INTERACT WITH THE
SAME FRONT THAT BENDS BACK ACROSS THE GREAT PLAINS. ROUNDS OF RAIN
AND THUNDERSTORMS ARE LIKELY TO CONTINUE INTO SUNDAY WITH POSSIBLY
MULTIPLE MCSS. ABOVE NORMAL MOISTURE AND INSTABILITY SHOULD SUPPORT
HIGH RAIN RATES AT TIMES. A BROAD MARGINAL RISK ON DAY 4/SUNDAY
COVERS MUCH OF THE PLAINS FROM THE TX/OK RED RIVER NORTH INTO THE
DAKOTAS, WITH JUST A BIT OF THE MISSISSIPPI VALLEY COVERED DUE TO
ISOLATED FLASH FLOODING CONCERNS. A SLIGHT RISK HAS BEEN INTRODUCED
WITHIN THE MARGINAL RISK WHERE THERE IS A CONVERGENCE OF THE
HIGHEST RAINFALL AMOUNTS FROM MODELS. THEN BY MONDAY, THERE IS A
GENERAL TREND FOR THE OHIO/TENNESSEE VALLEYS TO SEE INCREASING RAIN
AND THUNDERSTORMS AS THE FRONT MOVES EAST. THE UPPER TROUGH WILL
ALSO DEEPEN AND PROVIDE A SUPPORTIVE DYNAMICAL ENVIRONMENT FOR
THUNDERSTORMS, WHILE A TONGUE OF INSTABILITY REACHES NORTHWARD. THE
MARGINAL RISK IS MAINTAINED FROM THE SOUTHEAST NORTHWARD ACROSS
THE TENNESSEE LOWER OHIO VALLEYS. THERE REMAINS UNCERTAINTY WITH
THE DETAILS OF QPF DUE TO SUBTLE DIFFERENCES IN THE SHORTWAVES AND
SURFACE BOUNDARIES INVOLVED AS DISCUSSED IN THE PREVIOUS SECTION,
SO STAY TUNED FOR POSSIBLE FUTURE CHANGES. RAIN AND STORMS ARE
GENERALLY FORECAST TO OVERSPREAD THE EAST-CENTRAL U.S. TUESDAY AND
TOWARD THE EASTERN SEABOARD WEDNESDAY, WITH CHANGES TO THE DETAILS
LIKELY.
ELSEWHERE, SOME RAIN AND CONVECTION IS POSSIBLE ACROSS THE
INTERIOR NORTHWEST COINCIDENT WITH THE UPPER TROUGH. BY MONDAY
MOISTURE AND INSTABILITY WILL BE ABOVE NORMAL FOR THE NORTHERN
ROCKIES INTO THE NORTHERN HIGH PLAINS. A MARGINAL RISK IS
DEPICTED IN THE DAY 5/MONDAY ERO FOR NORTHWESTERN MONTANA AS THE
SHORTWAVE MOVES THROUGH AND PROVIDES LIFT. RAIN AND THUNDERSTORMS
ARE EXPECTED TO CONTINUE ACROSS THE NORTHERN PLAINS AND MIDWEST
TUESDAY-WEDNESDAY. MEANWHILE, THE FOUR CORNERS STATES COULD SEE
SOME INCREASING MONSOON SHOWERS UNDERNEATH THE BROAD RIDGE, AMID
THE RELATIVELY DRY MONSOON SEASON ESPECIALLY ACROSS UTAH/ARIZONA.
COOLER THAN AVERAGE TEMPERATURES ARE LIKELY ON THE COOL SIDE OF
THE MAIN FRONTAL SYSTEM EARLY NEXT WEEK. THE SOUTHEAST AND MUCH OF
THE CENTRAL U.S. CAN EXPECT HIGHS OF 5-10 DEGREES BELOW AVERAGE,
WITH LOCALLY GREATER ANOMALIES, AS HIGHS ONLY REACH THE 70S AND LOW
80S FOR PARTS OF THE SOUTHEAST. THESE TEMPERATURES SHOULD
GRADUALLY WARM CLOSER TO NORMAL AS THE WEEK PROGRESSES. THE
NORTHWEST WILL ALSO GENERALLY BE COOLER THAN AVERAGE UNDER ROUNDS
OF TROUGHING. THE MAIN HOTSPOT FOR TEMPERATURES WILL BE ACROSS THE
SOUTHWEST, WHERE LOWER DESERT AREAS CAN EXPECT HIGHS 105-115F, AND
TEMPERATURES WILL BE WARMING ABOVE NORMAL INTO THE SOUTHERN AND
CENTRAL HIGH PLAINS AS THE UPPER RIDGE EXPANDS. HEATRISK FROM THE
SOUTHWEST INTO TEXAS SHOWS SOME MAJOR (LEVEL 3/4) AREAS. SOME
RECORD HIGH TEMPERATURES THERE COULD BE CHALLENGED BY NEXT
WEDNESDAY. FLORIDA IS FORECAST TO SEE SEASONABLE TEMPERATURES IN
THE 90S, BUT WITH AMPLE HUMIDITY ALLOWING FOR SOME AREAS OF MAJOR
HEATRISK THERE AS WELL.
KONG/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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