740
FXUS02 KWBC 170736
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
336 AM EDT SUN MAY 17 2026
VALID 12Z WED MAY 20 2026 - 12Z SUN MAY 24 2026
***MULTIPLE ROUNDS OF HEAVY RAIN AND SEVERE STORMS EXPECTED FOR THE
SOUTHERN PLAINS, AND EARLY SEASON HEATWAVE ENDS FOR THE EAST
COAST STATES***
..GENERAL OVERVIEW
A MODERATELY AMPLIFIED UPPER LEVEL PATTERN OVER THE COUNTRY DURING
THE MIDDLE OF THE WEEK IS EXPECTED TO BECOME MORE QUASI-ZONAL BY
NEXT WEEKEND, AS THE TROUGH LIFTS OUT FROM THE ROCKIES AND THE
NORTHERN PLAINS, AND THE EASTERN U.S. RIDGE GETS FLATTENED WITH A
RETURN TO MORE TYPICAL TEMPERATURES FOR THE MONTH OF MAY, WITH
RELIEF FROM THE EARLY SEASON HEAT WAVE. A STALLING FRONTAL BOUNDARY
WITH SHORTWAVE IMPULSES ALOFT WILL FUEL THE DEVELOPMENT OF MULTIPLE
THUNDERSTORM COMPLEXES FROM TEXAS TO THE DEEP SOUTH, WITH EPISODES
OF HEAVY RAINFALL AND STRONG/SEVERE STORMS. MAINLY DRY CONDITIONS
ARE EXPECTED FOR MOST OF THE WESTERN U.S.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 00Z MODEL GUIDANCE SUITE FEATURES GOOD SYNOPTIC SCALE AGREEMENT
ACROSS THE COUNTRY FOR THE MIDDLE OF THE WEEK, WITH A GENERAL MODEL
COMPROMISE WORKING WELL AS A STARTING POINT FOR FRONTS/PRESSURES.
THE CMC HAS TRENDED CLOSER TO THE MODEL CONSENSUS WITH THE TROUGH
ACROSS THE WEST, AND NOT AS AMPLIFIED AS ITS 12Z RUN FROM
YESTERDAY. THE MODELS ARE IN GOOD AGREEMENT THAT THE COLD FRONT
REACHES THE CAROLINAS AND CLEARS THE MID-ATLANTIC BY THURSDAY
NIGHT, BUT THE 500MB PATTERN DOE NOT SHOW MUCH IN THE WAY OF UPPER
LEVEL TROUGHING BEHIND IT, SO THIS WILL TEND TO STALL THE FORWARD
PROGRESS OF THE BOUNDARY ACROSS THE SOUTHEAST AND DEEP SOUTH. THERE
WILL BE A RELATIVELY SHALLOW COLDER AIRMASS BEHIND IT WITH
POTENTIAL FOR A COLD AIR DAMMING TYPE SITUATION.
LOOKING AHEAD TO NEXT WEEKEND, THE CMC IS MORE AMPLIFIED WITH
TROUGHING OVER THE CENTRAL/NORTHERN PLAINS, AND MORE TIMING
DIFFERENCES EXISTS WITH SHORTWAVE FEATURES IN THE NORTHERN STREAM
FLOW. BY SUNDAY, THERE IS A DECENT MODEL SIGNAL FOR A TROUGH
APPROACHING THE PACIFIC NORTHWEST WITH A LEAD SHORTWAVE AHEAD OF
IT. THE ENSEMBLE MEANS WERE INCREASED TO ABOUT HALF BY THIS TIME
PERIOD.
..WEATHER/HAZARDS HIGHLIGHTS
HEAVY RAINFALL IS EXPECTED TO MAKE WEATHER HEADLINES GOING INTO THE
LATTER HALF OF THE WORK WEEK FROM WESTERN TEXAS TO THE TENNESSEE
RIVER VALLEY. THE HIGHEST QPF SHOULD BE ACROSS CENTRAL TEXAS WHERE
MULTIPLE MESOSCALE CONVECTIVE SYSTEMS WILL DEVELOP AND AFFECT THE
SAME AREAS ON MULTIPLE DAYS. FOR THE DAY 4/WEDNESDAY-WEDNESDAY
NIGHT TIME PERIOD, A SLIGHT RISK WILL BE VALID FROM NEAR DEL RIO TO
LONGVIEW, TEXAS WHERE 1-3 INCHES OF RAINFALL IS LIKELY WITH STORMS
PRODUCING HIGH RAINFALL RATES. THIS LINGERS GOING INTO THURSDAY AS
WELL WITH A BROAD MARGINAL RISK EXTENDING FROM THE RIO GRANDE TO
MISSISSIPPI, WITH POSSIBLE UPGRADES TO SLIGHT RISK IN FUTURE
OUTLOOKS AS TIMING AND PLACEMENT BECOME CLEARER. LIGHTER
PRECIPITATION IS EXPECTED FARTHER TO THE EAST ACROSS THE CAROLINAS
INTO VIRGINIA WITH THE COLD FRONT DROPPING SOUTH, AND ALSO FOR
PORTIONS OF THE OHIO VALLEY. VALLEY SHOWERS AND MOUNTAIN SNOW ARE
LIKELY FOR PORTIONS OF MONTANA AND WYOMING ON WEDNESDAY BEFORE A
DRIER WEATHER PATTERN ENSUES BY THE END OF THE WEEK.
IN TERMS OF TEMPERATURES, EXPECT ANOTHER DAY OF HOT WEATHER ACROSS
THE EAST COAST REGION ON WEDNESDAY WITH HIGHS REACHING THE LOWER TO
MIDDLE 90S FROM THE CAROLINAS TO SOUTHERN NEW ENGLAND, WITH THE
HOTTEST READINGS LIKELY TO BE OVER VIRGINIA. SOME DAILY RECORD
HIGHS ARE LIKELY GIVEN THE POTENTIAL FOR SOME 20 DEGREE ABOVE
AVERAGE ANOMALIES. A WELCOMED RELIEF IS EXPECTED TO ARRIVE ON
THURSDAY AS A STRONG COLD FRONT REACHES THE MID-ATLANTIC BY THIS
TIME, AND PROBABLY LASTING INTO FRIDAY AND SATURDAY AS WELL. A COLD
AIR DAMMING TYPE EVENT MAY BECOME ESTABLISHED EAST OF THE
APPALACHIANS WITH OVERCAST SKIES AND PERIODS OF MAINLY LIGHT RAIN
AT TIMES. THE FRONT LIKELY STALLS OVER THE SOUTHEAST WITH WARM AND
HUMID CONDITIONS CONTINUING SOUTH OF THE BOUNDARY. ELSEWHERE,
RELATIVELY COOL CONDITIONS ACROSS THE CENTRAL/NORTHERN PLAINS ARE
EXPECTED TO GRADUALLY WARM THROUGH THE FORECAST PERIOD.
HAMRICK
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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