475
FXUS02 KWBC 111859
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 PM EDT FRI JUL 11 2025
VALID 12Z MON JUL 14 2025 - 12Z FRI JUL 18 2025
..MUCH OF FLORIDA COULD SEE HEAVY RAIN NEXT WEEK
..OVERVIEW
A TYPICAL SUMMERTIME PATTERN WILL BE IN PLACE MUCH OF THE MEDIUM
RANGE PERIOD NEXT WEEK WITH AN EXPANSIVE UPPER RIDGE STRETCHED
ACROSS THE SOUTHERN U.S. AND PROGRESSIVE SHALLOW TROUGHS MOVING
THROUGH THE NORTHERN STREAM FLOW. A SHORTWAVE FROM THE BASE OF AN
INITIALLY ZONAL JET ACROSS CANADA WILL AMPLIFY OVER THE NORTHERN
ROCKIES BY TUESDAY, DRIFTING EAST THROUGH THE NORTHERN PLAINS AND
GREAT LAKES THROUGH FRIDAY. THIS TROUGH WILL SEND A COLD FRONT
THROUGH THE NORTHERN AND CENTRAL U.S. AIDING CONVECTION OVER MUCH
OF THE COUNTRY FROM THE ROCKIES AND EASTWARD. ELSEWHERE, WEAK LOW
PRESSURE NEAR/OVER FLORIDA WILL KEEP DAILY RAIN THREATS OVER THE
SUNSHINE STATE THROUGH THE WEEK, WHILE MONSOONAL MOISTURE INCREASES
THROUGHOUT THE WEEK IN THE FOUR CORNERS STATES TO SOUTH-CENTRAL
HIGH PLAINS. HEAT IN THE WEST EARLY TO MIDWEEK SHOULD LESSEN BY
LATER NEXT WEEK, WHILE WARMER THAN AVERAGE TEMPERATURES AFFECT THE
OHIO VALLEY TO NORTHEAST AROUND TUESDAY-THURSDAY.
..GUIDANCE/PREDICTABILITY ASSESSMENT
AI/ML AND OPERATIONAL MODELS STRUGGLE WITH THE DETAILS OF TIMING
AND DEPTH OF TROUGHS MOVING THROUGH THE MAIN FLOW, AS WELL AS
PLACEMENT OF WEAK ENERGIES FARTHER SOUTH, DESPITE OVERALL AGREEMENT
IN THE LARGER SCALE PATTERN. A SHORTWAVE/POTENTIALLY A SMALL CLOSED
LOW SHOULD DIG THROUGH BRITISH COLUMBIA/ALBERTA TUESDAY INTO THE
INTERIOR NORTHWEST MIDWEEK AND THEN EASTWARD. OF THE DETERMINISTIC
MODELS, THE 00Z GFS WAS ON THE SLOWER SIDE, SO FAVORED THE 06Z RUN.
AI/ML AND OPERATIONAL MODELS ALIKE SHOWED A FAIR AMOUNT OF SPREAD
IN THE TROUGH'S TIMING AS IT BROADENS AND TRACKS EAST. THIS
FORECAST TRENDED TOWARD THE ASSOCIATED COLD FRONT MOVING MORE
QUICKLY EAST THROUGH THE GREAT LAKES AND NORTHEAST WEDNESDAY-
THURSDAY, BUT WITH LOW CONFIDENCE. THEN ANOTHER TROUGH POSSIBLY
APPROACHING THE WEST LATE PERIOD ALSO SHOWS SPREAD IN ITS EVOLUTION
PARTIALLY RELATED TO A NORTHEASTERN PACIFIC UPPER LOW. THE WPC
FORECAST USED A MULTI-MODEL DETERMINISTIC BLEND FAVORING THE 06Z
GFS AND 00Z ECMWF EARLY ON, AND GRADUALLY REDUCED THE DETERMINISTIC
PROPORTION IN FAVOR OF THE ENSEMBLE MEANS TO OVER HALF BY THE END
OF THE PERIOD.
..WEATHER/HAZARDS HIGHLIGHTS
SEVERAL AREAS CAN EXPECT LOCALLY HEAVY RAIN WITH POTENTIAL FOR
FLASH FLOODING NEXT WEEK. FIRST, SHOWERS AND STORMS ARE LIKELY IN
THE EAST ON MONDAY AS MOISTURE AND INSTABILITY POOL ALONG AND AHEAD
OF A COLD FRONT. A MARGINAL RISK REMAINS IN PLACE ACROSS THE
NORTHEAST/MID-ATLANTIC/CAROLINAS IN THE DAY 4/MONDAY ERO. THE COLD
FRONT SHOULD BE MORE PROGRESSIVE IN THE NORTHERN HALF OF THE
MARGINAL, FOR LESS RESIDENCE TIME OF HEAVY RAIN, BUT MOISTURE
ANOMALIES ARE HIGHER THERE COMPARED TO SOUTHERN AREAS THAT MAY SEE
SLOWER MOVING CONVECTION. AS THE WEAK FRONT MOVES SOUTHWARD,
CHANCES FOR SLOW MOVING STORMS IN A MOIST AND UNSTABLE ENVIRONMENT
COULD CONTINUE ACROSS THE CAROLINAS/SOUTHEAST, THOUGH WITH SOME
MODEL SPREAD IN WHERE EXACTLY THE CONVECTION MAY BE MAXIMIZED
(SOUTHERN APPALACHIANS, COASTAL AREAS, OR IN BETWEEN). BROADENED A
MARGINAL RISK ON THE DAY 5/TUESDAY ERO TO INCLUDE THESE AREAS, BUT
THE AREAL EXTENT MAY BE ABLE TO LESSEN IN FUTURE CYCLES IF MODELS
AGREE BETTER ON A FOCUS FOR CONVECTION. SCATTERED THUNDERSTORMS
COULD PERSIST IN PARTS OF THE APPALACHIANS/EAST INTO MIDWEEK AND
BEYOND.
JUST TO THE SOUTH, A WEAK SURFACE TROUGH/LOW IS FORECAST TO
RETROGRADE FROM EAST OF GEORGIA MONDAY WESTWARD ACROSS NORTHERN
FLORIDA AND INTO THE GULF TUESDAY-WEDNESDAY. ENHANCED MOISTURE AND
THIS FORCING COULD LEAD TO HEAVY RAIN, WITH POSSIBLE TOTALS OF
MULTIPLE INCHES, LIKELY MAXIMIZED ON MONDAY ACROSS THE FLORIDA
PENINSULA. THERE IS SIGNIFICANT UNCERTAINTY THOUGH IN EXACTLY HOW
MUCH RAIN WILL FALL, AND WITH HIGH FLASH FLOOD GUIDANCE VALUES,
MAINTAINED JUST BROAD MARGINALS OVER THE STATE FOR THE MONDAY AND
TUESDAY ERO PERIODS. BY WEDNESDAY-THURSDAY, THE LOW BEING LOCATED IN
THE GULF SHOULD ALLOW THE PRIMARY RAINFALL FOCUS TO BE ALONG THE
CENTRAL/EASTERN GULF COAST.
FARTHER NORTH, SOMEWHAT MORE STRONGLY FORCED SYSTEMS COULD LEAD TO
HEAVY RAIN IN THE NORTHERN TIER MOVING EAST. A COLD FRONT MOVING
THROUGH THE NORTHERN/CENTRAL PLAINS AND EASTWARD NEXT WEEK WILL
SUPPORT SHOWERS AND THUNDERSTORMS WITH AMPLE MOISTURE AND
INSTABILITY, RESULTING IN A HEAVY TO EXCESSIVE RAINFALL THREAT. A
MARGINAL RISK IS HIGHLIGHTED FOR THE NORTH-CENTRAL U.S. ON MONDAY,
EXPANDING ACROSS MUCH OF THE EASTERN PLAINS AND MIDDLE/UPPER
MISSISSIPPI VALLEY TOWARD THE UPPER GREAT LAKES ON TUESDAY, THOUGH
STILL WITH PLENTY OF UNCERTAINTY IN EXACTLY WHERE THE HEAVIER RAIN
FALLS. THIS ACTIVITY SHOULD MOVE EAST INTO THE OHIO VALLEY AND THE
EAST COAST NEXT WEDNESDAY AND THURSDAY. FARTHER WEST, AREAS CLOSER
TO THE SHORTWAVE FORCING AND THE BACK END OF THE FRONT COULD SEE
HEAVY RAIN, NAMELY THE NORTHERN ROCKIES AND NORTHERN HIGH PLAINS
MONDAY-TUESDAY, AND MARGINAL RISKS ARE ALSO IN PLACE THERE.
WEAK UPPER ENERGY ACROSS TEXAS EMBEDDED WITHIN THE MEAN
SUBTROPICAL UPPER RIDGE AND ABOVE AVERAGE MOISTURE COULD CONTINUE A
HEAVY RAIN THREAT FROM THE SOUTHERN PLAINS JUST REACHING THE
LOWER/MIDDLE MISSISSIPPI VALLEY ON MONDAY, WHERE THERE IS A
MARGINAL RISK IN THE DAY 4 ERO. BY DAY 5/TUESDAY, WILL HIGHLIGHT A
MARGINAL IN FAR WEST TEXAS INTO THE SACRAMENTO MOUNTAINS (WITH BURN
SCARS PARTICULARLY SENSITIVE IN THE LATTER) AS MOISTURE LINGERS
OVER TERRAIN. AS THE WEEK PROGRESSES, MONSOONAL MOISTURE INCREASES
ACROSS THE SOUTHWEST/FOUR CORNERS/SOUTHERN ROCKIES REGION.
HOT WEATHER WILL REMAIN FOR MUCH OF THE WESTERN U.S. THROUGH
MONDAY AS UPPER RIDGING PERSISTS. DAILY HIGHS WILL BE ABOVE NORMAL
WITH MANY LOCATIONS CLIMBING INTO THE 100S AND 110S FOR THE DESERT
SOUTHWEST, AND NEARING/EXCEEDING 100F FARTHER NORTH IN
INTERIOR/LOWER ELEVATION AREAS OF THE GREAT BASIN. TEMPERATURES
WILL MODERATE BELOW NORMAL BY TUESDAY FOR THE NORTHERN PLAINS WITH
HIGH TEMPERATURES 15 TO 25 DEGREES BELOW NORMAL FOR TUESDAY AND
WEDNESDAY. TEMPERATURES LOOK TO BE A FEW DEGREES COOLER THAN
AVERAGE FOR THE SOUTH-CENTRAL U.S. FOR MUCH OF NEXT WEEK AS CLOUDS
AND RAIN HOLD TEMPERATURES DOWN. THE GREAT LAKES AND NORTHEAST
WILL SEE A RETURN TO ABOVE NORMAL TEMPERATURES ON TUESDAY AFTER THE
TROUGH CLEARS, WITH SOME MAJOR (LEVEL 3/4) HEATRISK SHOWING UP IN
THOSE AREAS BY MIDWEEK. MEANWHILE THE SOUTHEAST SHOULD BE NEAR
NORMAL TO A FEW DEGREES ABOVE, FOR TYPICAL SUMMER HEAT AND
HUMIDITY.
TATE/SANTORELLI
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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