077
FXUS02 KWBC 231848
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
248 PM EDT SUN MAR 23 2025
VALID 12Z WED MAR 26 2025 - 12Z SUN MAR 30 2025
..OVERVIEW
EXPECT THE AMPLIFIED WESTERN RIDGE/EASTERN TROUGH UPPER PATTERN
LINGERING INTO WEDNESDAY TO MOVE STEADILY EASTWARD WHILE TRENDING A
LITTLE FLATTER, AS DYNAMICS FROM A STRONG EAST PACIFIC UPPER
TROUGH WEDNESDAY-THURSDAY (SUPPORTING A STORM SYSTEM OFF THE
PACIFIC NORTHWEST COAST) PUSH INTO THE WESTERN AND CENTRAL U.S.
WITH A SLIGHTLY SLOWER TREND NOTED IN THE GUIDANCE, THE MEAN RIDGE
SHOULD REACH THE EAST BY NEXT WEEKEND. EXPECT VERY WARM
TEMPERATURES UNDER THE WESTERN UPPER RIDGE THROUGH MIDWEEK OR SO
WITH SOME DAILY RECORDS POSSIBLE. ANOMALOUS WARMTH WILL THEN MOVE
INTO THE PLAINS, FOLLOWED BY MODERATION FARTHER EAST. UPPER
DYNAMICS AND THE LEADING FRONT ARRIVING FROM THE PACIFIC WILL BRING
RAIN AND HIGH ELEVATION SNOW TO THE NORTHWEST MID-LATE WEEK, WITH
ANOTHER SYSTEM POSSIBLY APPROACHING BY NEXT SUNDAY. A SOUTHERN TIER
SHORTWAVE WILL SUPPORT THE THREAT OF LOCALLY HEAVY RAINFALL OVER
PARTS OF TEXAS LATE IN THE WEEK. THIS MOISTURE AND ADDITIONAL GULF
INFLOW MAY COMBINE TO SPREAD A BROADER AREA OF PRECIPITATION OVER
PARTS OF THE PLAINS AND EAST-CENTRAL U.S. LATE WEEK INTO THE
WEEKEND, IN ASSOCIATION WITH PLAINS THROUGH UPPER MIDWEST LOW
PRESSURE.
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE CONTINUES TO SHOW GOOD AGREEMENT ON THE LARGE SCALE UPPER
PATTERN AND PROGRESSION, BUT A LOT OF UNCERTAINTY IN THE DETAILS.
A LEADING SHORTWAVE INTO THE WEST FROM A DEEPENED LOW OFF THE
PACIFIC NORTHWEST COAST SHOWS GOOD AGREEMENT, BUT THERE IS
CONTINUED QUESTION ON TIMING AND AMPLITUDE OF A DEEPER TROUGH INTO
THE WEST LATER IN THE WEEK. THE GFS HAS TRENDED SLIGHTLY DEEPER IN
RECENT DAYS, BUT THE LAST SEVERAL RUNS OF THE CMC CONTINUES TO BE
THE OUTLIER AS IT EVENTUALLY SPINS UP A CLOSED LOW OVER THE CENTRAL
PLAINS NEXT WEEKEND. BETTER CLUSTER OF GUIDANCE SUGGESTS THIS
SHOULD BE MORE OF AN OPEN WAVE. AHEAD OF THIS THOUGH, THERE REMAINS
UNCERTAINTY IN THE DETAILS OF A SOUTHERN STREAM SHORTWAVE INTO THE
SOUTHERN PLAINS AND MIDWEST LATER THIS WEEK, WHICH HAS IMPACTS ON
HEAVY RAINFALL POTENTIAL ACROSS TEXAS. THEN BY NEXT WEEKEND
GUIDANCE SHOWS SPREAD WITH A FRONT THAT REACHES INTO THE MID-
ATLANTIC, LIKELY WITH A PRONOUNCED TEMPERATURE GRADIENT.
THE WPC FORECAST TODAY WAS ABLE TO USE A BLEND OF THE LATEST
DETERMINISTIC GUIDANCE FOR WEDNESDAY AND THURSDAY, AMIDST GOOD
MODEL AGREEMENT. BEGAN INCORPORATING THE ECENS/GEFS BY FRIDAY/DAY
5, EVENTUALLY REACHING A 50/50 SPLIT OF DETERMINISTIC/ENSEMBLE
MEANS BY DAY 7. DID NOT INCLUDE THE CMC IN THE LATE PERIOD BLEND
DUE TO THE OUTLIER SOLUTION DESCRIBED ABOVE. OVERALL, THIS APPROACH
MAINTAINED GOOD CONTINUITY WITH THE PREVIOUS WPC FORECAST.
..WEATHER/HAZARDS HIGHLIGHTS
FROM WEDNESDAY INTO THURSDAY NIGHT THE MOST PROMINENT HEAVY
RAINFALL FOCUS SHOULD BE OVER PORTIONS OF TEXAS BY THURSDAY AS
MOIST SOUTHEASTERLY LOW LEVEL FLOW FROM THE GULF INTERACTS WITH AN
UPPER SHORTWAVE CROSSING NORTHERN MEXICO. SOME ACTIVITY MAY
INITIATE IN THE DAY 4 PERIOD NEAR THE RIO GRANDE VALLEY BUT THE
SIGNAL IS DIFFUSE ENOUGH NOT TO MERIT ANY RISK AREA IN THE
EXCESSIVE RAINFALL OUTLOOK. BY DAY 5 THERE IS A MUCH STRONGER
SIGNAL, THOUGH WITH TYPICAL SPREAD FOR WHERE THE HEAVIEST RAINFALL
AXIS WILL BE. OVERALL THE BEST OVERLAP OF GUIDANCE EXISTS OVER
SOUTHERN TEXAS. THE DAY 5 ERO MAINTAINS A BROADER MARGINAL RISK
AREA, WITH NO EMBEDDED SLIGHT RISK DEPICTED YET DUE TO INITIALLY
DRY GROUND CONDITIONS AND GUIDANCE SPREAD. IMPROVED CLUSTERING FOR
LOCATION AND AMOUNTS IN THE HEAVIER PART OF THE ENVELOPE COULD
EVENTUALLY MERIT AN UPGRADE. ELSEWHERE, CONSENSUS AMOUNTS ALONG THE
PACIFIC NORTHWEST COAST IN ASSOCIATION WITH THE WEDNESDAY-
THURSDAY SYSTEM HAVE GENERALLY DECREASED SOMEWHAT FROM 24 HOURS
AGO, WHILE THE SIGNAL FOR A POTENTIAL BAND OF ENHANCED RAINFALL
OVER THE MID MISSISSIPPI VALLEY AHEAD OF A WARM FRONT IS TOO
DIFFUSE TO WARRANT A RISK AREA YET ON DAY 5.
PRECIPITATION WILL SPREAD ACROSS NORTHERN AND CENTRAL PARTS OF THE
WEST LATE THIS WEEK, WITH PLAINS LOW PRESSURE AND ITS TRAILING
FRONT EVENTUALLY PUSHING THE TEXAS RAINFALL EASTWARD WHILE
SPREADING A BROADER SHIELD OF MOISTURE ACROSS THE CENTRAL AND EAST-
CENTRAL U.S. SOME WINTRY WEATHER WILL BE POSSIBLE OVER FAR
NORTHERN LATITUDES BUT OTHERWISE MOST PRECIPITATION SHOULD BE IN
THE FORM OF RAIN. HOW MUCH SNOW FALLS OVER THE NORTHERN PLAINS NEXT
WEEKEND WILL DEPEND ON HOW STRONGLY THE PLAINS/UPPER MIDWEST
SYSTEM DEVELOPS, WITH LOW CONFIDENCE IN SPECIFICS AT THIS TIME. THE
NEXT PACIFIC SYSTEM MAY INCREASE PRECIPITATION ALONG THE WEST
COAST BY NEXT SUNDAY.
THE WEAK WAVE FORECAST TO TRACK OFF THE MID-ATLANTIC/NEW ENGLAND
COAST ON WEDNESDAY MAY PRODUCE SOME LIGHT PRECIPITATION EARLY BUT
MOST LIKELY JUST NEAR THE COAST.
THE STRONG UPPER RIDGE OVER THE WEST INTO WEDNESDAY 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 DURING WEDNESDAY. AS THE UPPER RIDGE SHIFTS EASTWARD
WITH TIME, THE WEST WILL COOL DOWN WHILE ALREADY ABOVE NORMAL
ANOMALIES OVER THE CENTRAL U.S. WILL INCREASE. LOCATIONS FROM THE
NORTHERN-CENTRAL PLAINS INTO MIDWEST SHOULD SEE ONE OR TWO DAYS OF
HIGHS REACHING 20-25F OR SO ABOVE NORMAL BY THURSDAY-FRIDAY, WITH
BEST POTENTIAL FOR SOME DAILY RECORDS OVER THE CENTRAL HIGH PLAINS
ON THURSDAY. THE EAST WILL SEE NEAR TO SLIGHTLY BELOW NORMAL
TEMPERATURES WEDNESDAY-THURSDAY AND THEN INCREASING COVERAGE OF
HIGHS 10-20F ABOVE NORMAL FRIDAY INTO THE WEEKEND. HOWEVER A FRONT
REACHING THE NORTHEAST/MID-ATLANTIC MAY DEFINE A SHARP GRADIENT
BETWEEN THIS WARMTH AND COOLER READINGS JUST TO THE NORTH.
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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