003
FXUS02 KWBC 211900
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 PM EDT FRI MAR 21 2025
VALID 12Z MON MAR 24 2025 - 12Z FRI MAR 28 2025
..OVERVIEW
THE EARLY TO MIDDLE PART OF NEXT WEEK WILL FEATURE A LARGE-SCALE
WESTERN U.S. UPPER RIDGE AND EASTERN TROUGH. THE PATTERN SHOULD
FLATTEN/PROGRESS SOME LATER IN THE WEEK, AS ENERGY FROM AN EASTERN
PACIFIC TROUGH REACHES INTO THE WEST WHILE THE RIDGE MOVES INTO THE
PLAINS/MISSISSIPPI VALLEY AND THE EASTERN TROUGHING BEGINS TO LIFT
OUT. EXPECT VERY WARM TEMPERATURES UNDER THE UPPER RIDGE WITH SOME
DAILY RECORDS POSSIBLE OVER THE WEST. THE GREAT LAKES AND EAST
COAST/GULF COAST WILL SEE ONE EPISODE OF PRECIPITATION WITH A
MONDAY SYSTEM WITH A POSSIBLE MIDWEST WAVE ON TUESDAY POTENTIALLY
SPREADING SOME MOISTURE INTO THE EAST BY MIDWEEK. THE UPPER
DYNAMICS AND LEADING FRONT REACHING THE WEST WILL BRING RAIN AND
HIGH ELEVATION SNOW TO THE NORTHWEST MID-LATE WEEK. MEANWHILE A
SOUTHERN TIER SHORTWAVE WILL BRING A THREAT OF LOCALLY HEAVY
RAINFALL TO PARTS OF THE SOUTHERN HALF OF TEXAS LATE IN THE WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS AND ENSEMBLES SHOW GOOD AGREEMENT ON THE LARGE SCALE, BUT
STILL A LOT OF UNCERTAINTY IN THE DETAILS. THERE IS GOOD
CONSISTENCY WITH THE EASTERN U.S. SYSTEM ON MONDAY-TUESDAY, BUT
STILL SPREAD WITH THE NEXT WAVE INTO THE MIDWEST AND TOWARDS THE
NORTHEAST. THIS SECOND FEATURE THOUGH HAS FAIRLY LOW PREDICTABILITY
DUE TO BEING VERY SENSITIVE TO SMALL SCALE DETAIL DIFFERENCES IN
SUPPORTING SHORTWAVE ENERGY. BY MID TO LATE WEEK, SOME CONTINUED
SPREAD AS THE NEXT TROUGH ENTERS THE WEST. OVERNIGHT ECMWF RUNS
WERE SHARPER THAN PREVIOUS RUNS (AND OTHER GUIDANCE), SO DID NOT
PUT MUCH WEIGHT ON THAT SOLUTION IN THE BLEND TODAY. CMC/ECMWF RUNS
ARE ALSO FASTER THAN THE GFS WITH THE TROUGH.
WPC BLEND FOR TODAY FAVORED THE DETERMINISTIC MODELS EARLY PERIOD,
TRENDING TOWARDS SLIGHT MAJORITY ENSEMBLE MEANS LATER IN THE
PERIOD. THIS MAINTAINED GOOD CONTINUITY WITH PREVIOUS WPC FORECASTS
AS WELL.
..WEATHER/HAZARDS HIGHLIGHTS
LOW PRESSURE TRACKING FROM THE GREAT LAKES EASTWARD EARLY IN THE
WEEK WILL PRODUCE SOME SNOW OVER FAR NORTHERN AREAS, WITH BEST
POTENTIAL FOR MEANINGFUL ACCUMULATION ON MONDAY OVER CENTRAL AND
NORTHERN NEW ENGLAND. EXPECT RAIN FARTHER SOUTH ALONG THE TRAILING
COLD FRONT. THE DAY 4/MONDAY EXCESSIVE RAINFALL OUTLOOK HOLDS ONTO
A MARGINAL RISK AREA OVER PARTS OF THE GULF COAST IN LIGHT OF
LINGERING TRAINING POTENTIAL THAT IS MOST PROMINENTLY SUGGESTED IN
THE GFS. HOWEVER OTHER GUIDANCE IS LESS ENTHUSIASTIC QPF-WISE AND
IT IS A FAIRLY PROGRESSIVE FRONT, SO WOULD CONSIDER THIS A LOWER-
END THREAT AT THIS TIME. BEHIND THIS SYSTEM A WEAK WAVE MAY TRACK
THROUGH THE MIDWEST AROUND TUESDAY AND THEN NEAR THE NORTHEAST
COAST BY WEDNESDAY. ANY ASSOCIATED PRECIPITATION SHOULD BE FAIRLY
LIGHT AND CONFIDENCE IN THE SYSTEM'S EVOLUTION IS BELOW AVERAGE AT
THIS TIME.
FAR NORTHERN PARTS OF THE WEST MAY SEE LINGERING PRECIPITATION ON
MONDAY WITH MOST OF THE REGION DRY BY TUESDAY. UPPER TROUGH ENERGY
AND A LEADING COLD FRONT WILL BRING ANOTHER ROUND OF RAIN AND HIGH
ELEVATION SNOW INTO THE NORTHWEST AND NORTHERN ROCKIES MID-LATE
WEEK. THERE IS SOME UNCERTAINTY OVER AMOUNTS AND SOUTH AND INLAND
EXTENT.
AROUND TUESDAY-TUESDAY NIGHT SOME GUIDANCE HINTS AT THE POTENTIAL
FOR VERY LOCALIZED ENHANCED RAINFALL OVER PARTS OF THE SOUTHERN
PLAINS, NEAR THE FRONT TRAILING FROM THE WEAK MIDWEST WAVE. THIS
POTENTIAL ACTIVITY IS NOT SUFFICIENTLY AGREEABLE OR ORGANIZED IN
THE GUIDANCE TO MERIT AN ERO RISK AREA AT THIS TIME. GROUND
CONDITIONS ARE ALSO FAIRLY DRY OVER THIS REGION. THEN THE
COMBINATION OF AN APPROACHING SOUTHERN STREAM TROUGH ALONG WITH
MOIST EASTERLY LOW LEVEL FLOW FROM THE GULF MAY INCREASE THE
CHANCES FOR MORE ORGANIZED AND HEAVIER RAINFALL OVER PARTS OF
SOUTHERN TEXAS LATE IN THE WEEK.
THE STRONG UPPER RIDGE OVER THE WEST EARLY-MID WEEK WILL BRING
WELL ABOVE NORMAL TEMPERATURES TO THE REGION, WITH A BROAD AREA OF
HIGHS 10-20F ABOVE NORMAL WITH LOCALLY HIGHER ANOMALIES. THERE WILL
ALSO BE POTENTIAL FOR NUMEROUS DAILY RECORDS FOR HIGHS/WARM LOWS,
ESPECIALLY ON TUESDAY AND WEDNESDAY. SOME PLACES OVER THE DESERT
SOUTHWEST COULD GET CLOSE TO 100 DEGREES. AS THE UPPER PATTERN
SHIFTS EASTWARD SOMEWHAT LATER IN THE WEEK, THE WEST WILL COOL DOWN
WHILE ALREADY ABOVE NORMAL ANOMALIES OVER THE CENTRAL U.S. WILL
INCREASE. AREAS OVER AND NEAR THE CENTRAL PLAINS SHOULD SEE HIGHS
REACH 20-25F ABOVE NORMAL BY THURSDAY-FRIDAY. MEAN TROUGHING ALOFT
WILL KEEP MOST OF THE EAST NEAR TO SLIGHTLY BELOW NORMAL FOR
TEMPERATURES.
SANTORELLI/RAUSCH
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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