736
FXUS02 KWBC 141853
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
253 PM EDT MON APR 14 2025
VALID 12Z THU APR 17 2025 - 12Z MON APR 21 2025
...HEAVY RAINFALL AND FLOODING POSSIBLE IN PARTS OF THE CENTRAL
U.S. BY THE WEEKEND...
..OVERVIEW
STARTING THURSDAY A VIGOROUS UPPER TROUGH WILL BE TRAVERSING
THROUGH THE NORTHWEST AS SOUTHERN STREAM TROUGHING SETUPS UP OVER
THE SOUTHWEST. THESE TWO FEATURES WILL COMBINE TO YIELD AN UPPER
LOW OVER THE GREAT BASIN REGION LATE IN THE WEEK AND WITH TIME,
PIVOT TO THE SOUTH AND EAST THROUGH THE WEEKEND. COOLER
TEMPERATURES ALONG WITH INCREASED POTENTIAL FOR PRECIPITATION, SOME
OF WHICH MAY BE HEAVY SNOWFALL FOR THE NORTHERN/CENTRAL ROCKIES
THROUGH FRIDAY. IN ADDITION, THERE WILL BE NORTHERN STREAM TROUGH
ADVANCING THROUGH THE NORTH-CENTRAL AND NORTHEASTERN U.S.
ACCOMPANIED BY A LOW PRESSURE SYSTEM, AS AN ELONGATED FRONTAL
SYSTEM STRETCHES FROM THE NORTHERN TIER SOUTHWESTWARD THROUGH THE
SOUTH-CENTRAL U.S. LATE WEEK INTO THE WEEKEND. RAIN AND
THUNDERSTORMS ARE EXPECTED WITH THIS FEATURE ALONG WITH THE
POSSIBILITY OF SEVERE STORMS. HEAVY RAINFALL AND POSSIBLE FLOODING
TO DEVELOP ACROSS THE SOUTH-CENTRAL U.S WHERE MOISTURE STREAMING
AHEAD OF THE SOUTHWEST UPPER LOW WILL INTERACT WITH FRONTAL SYSTEMS
OVER THE REGION. THE GREATEST POTENTIAL WILL BE OVER THE WEEKEND.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST RUNS OF GUIDANCE MAINTAIN THE SYNOPTIC PATTERN FROM
ABOVE WHILE HANGING ON TO SOME OF THE TENDENCIES OBSERVED FROM THE
THE PREVIOUS FORECAST PACKAGE. THE USE OF A MULTI-MODEL APPROACH
MAINTAINED A SENSE OF CONTINUITY AND REDUCED SOME OF THE MINOR
DIFFERENCES WITH THE TIMING AND LOCATION OF THE NORTHERN AND
SOUTHERN STREAM TROUGHING. AS PREVIOUSLY NOTED, THE GFS IS HANGING
ON TO A SLOW PROGRESSION OF THE TROUGH/LOW OVER THE GREAT
BASIN/SOUTHWEST WHICH IMPACTS THE QPF OVER THE CENTRAL/SOUTHERN
HIGH PLAINS WHEREAS THE OTHER GUIDANCE FAVORS QPF MORE TO THE SOUTH
AND EAST OF THE EXPECTED FRONTAL POSITIONS. THE CMC HAS TRENDED
SOMEWHAT TOWARD THE GFS SOLUTION HOWEVER, THE ECWMF IS PROVIDING
THE FAVORED PLACEMENT AND ASSOCIATED DETAILS AT THIS TIME.
THE WPC FORECAST WAS BASED ON A BLEND OF THE DETERMINISTIC
GUIDANCE USING THE 00Z ECMWF, 06/12Z GFS, 00Z CMC, AND 00Z UKMET
INITIALLY WHILE LIGHT WEIGHTING OF THE ECWMF AND GEFS MEANS WERE
INCORPORATED FOR THE WEEKEND AND INTO EARLY NEXT WEEK TO TEMPER
THE MODEL DIFFERENCES.
..WEATHER/HAZARDS HIGHLIGHTS
STRONG UPPER-LEVEL ENERGY WILL PROVIDE SUPPORT FOR MODERATE TO
HEAVY PRECIPITATION ACROSS PARTS OF THE WEST, STRETCHING FROM THE
NORTHERN/CENTRAL ROCKIES AND HIGH PLAINS ACROSS THE INTERMOUNTAIN
WEST INTO THE SIERRA NEVADA. COLDER AIR ALOFT WILL LIKELY LEAD TO
ACCUMULATING SNOW IN THE HIGHER ELEVATION, PARTICULARLY HEAVY ACROSS
WYOMING AND SOUTHERN MONTANA WITH SOME AREAS OF SNOW FOR THE
WASATCH AND SIERRA. SOME PRECIPITATION IS FORECAST TO CONTINUE IN
THE FOUR CORNERS STATES INTO THE WEEKEND, WITH POSSIBLY MULTIPLE
DAYS OF SNOW IN THE COLORADO ROCKIES.
FARTHER EAST, THE NORTHERN STREAM UPPER TROUGH AND A SURFACE LOW
PRESSURE SYSTEM WILL TRAVERSE THE NORTH-CENTRAL PLAINS AND MIDWEST
ON THURSDAY, SUPPORTING SHOWER AND THUNDERSTORM ACTIVITY. THE
STORM PREDICTION CENTER HAS IDENTIFIED THESE AREAS AS HAVING A
SEVERE WEATHER RISK. GIVEN THE PROGRESSIVENESS OF THE LOW, THE
LOCALLY HEAVY RAIN WILL HAVE LIMITED POTENTIAL FOR FLOODING.
INDIVIDUAL THUNDERSTORMS SHOULD MOVE QUICKLY BUT THERE MAY BE
REPEATED ROUNDS MOVING WEST TO EAST SOMEWHERE IN THE VICINITY OF
LOWER MICHIGAN AND/OR INDIANA/OHIO. WITH ANTECEDENT DRY CONDITIONS
AND UNCERTAINTY WITH THE AXIS OF POTENTIAL HEAVY RAIN THERE WILL
NOT BE AN AREA FOR THE EXCESSIVE RAINFALL OUTLOOK HOWEVER WILL
CONTINUE TO MONITOR FLOODING POTENTIAL. FARTHER SOUTH, THE TAIL END
OF THE FRONTAL SYSTEM IN THE SOUTHERN PLAINS SHOULD HELP TO FOCUS
MOISTURE ADVECTION AHEAD OF THE SOUTHWEST UPPER LOW. SOME RAIN AND
STORMS BECOME LIKELY BY FRIDAY EVENING OR NIGHT OVER PARTS OF TEXAS
AND OKLAHOMA, WITH SOME LIKELY LESSER AMOUNTS OVER
ARKANSAS/MISSOURI. BY SATURDAY HEAVY RAIN IS LIKELY TO CONTINUE IN
THE SOUTHERN PLAINS, AND THIS SHOULD WARRANT ERO AREAS, BUT THIS IS
BEYOND THE DAY 5 ERO PERIOD. THE SURFACE LOW AND FRONTAL SYSTEM IS
EXPECTED TO SHIFT NORTHEAST BY SUNDAY WHICH WILL ALLOW THE RAIN
AND THUNDERSTORMS TO SPREAD INTO THE CENTRAL/SOUTHERN PLAINS AND
THE MIDDLE/LOWER MISSISSIPPI VALLEY. HEAVIEST RAINFALL AMOUNTS ARE
LIKELY TO BE WEST OF THE MOST SENSITIVE AREAS OF THE MISSISSIPPI
VALLEY AND OHIO VALLEY FROM RECENT FLOODING. HOWEVER, SOME RAIN
ATOP RECENTLY FLOODED AREAS, AND RUNOFF FROM OTHER AREAS INTO THESE
RIVERS, COULD EXACERBATE ONGOING FLOODING ISSUES IN SOME AREAS.
THE FORECAST DETAILS COULD CHANGE OVER THE NEXT FEW DAYS AND SHOULD
BE CLOSELY MONITORED TO ASSESS ANY POSSIBLE IMPACTS.
INITIAL UPPER RIDGING ACROSS THE PLAINS WILL ALLOW FOR ABOVE
NORMAL TEMPERATURES THERE ON THURSDAY. ABOVE NORMAL HIGHS BY 20-25
DEGREES WILL RAISE HIGHS INTO THE 90S FROM TEXAS TO KANSAS.
MEANWHILE COOLER THAN NORMAL TEMPERATURES, ESPECIALLY FOR HIGHS,
ARE LIKELY TO SPREAD ACROSS THE INTERIOR WEST THURSDAY AND FRIDAY
UNDER THE UPPER TROUGH. WARMER THAN AVERAGE TEMPERATURES ARE
FORECAST TO MODERATE AND SHIFT EAST INTO LATE WEEK AND FOCUS ACROSS
THE SOUTHEASTERN U.S. BY SUNDAY.
CAMPBELL/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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