799
FXUS02 KWBC 221810
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
210 PM EDT SAT MAR 22 2025
VALID 12Z TUE MAR 25 2025 - 12Z SAT MAR 29 2025
..OVERVIEW
AN AMPLIFIED WESTERN RIDGE/EASTERN TROUGH UPPER PATTERN AS OF
TUESDAY WILL GRADUALLY PROGRESS EASTWARD WHILE TRENDING FLATTER, AS
DYNAMICS FROM A STRONG MIDWEEK UPPER TROUGH (SUPPORTING A STORM
SYSTEM OFF THE PACIFIC NORTHWEST COAST) PUSH INTO THE WESTERN HALF
OF THE LOWER 48. THE MEAN RIDGE SHOULD REACH THE EAST BY FRIDAY OR
SATURDAY. EXPECT VERY WARM TEMPERATURES UNDER THE WESTERN UPPER
RIDGE THROUGH MIDWEEK 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. A SOUTHERN TIER SHORTWAVE WILL SUPPORT THE
THREAT OF LOCALLY HEAVY RAINFALL OVER PARTS OF TEXAS LATE IN THE
WEEK, WITH THIS MOISTURE AND ADDITIONAL GULF INFLOW POTENTIALLY
COMBINING TO SPREAD A BROADER AREA OF MOSTLY RAIN OVER PARTS OF THE
PLAINS AND EAST-CENTRAL U.S. BY THE END OF THE WEEK. A WEAK
MIDWEST WAVE ON TUESDAY MAY PRODUCE A BAND OF MOSTLY LIGHT
PRECIPITATION NEAR ITS TRACK THAT MAY EXTEND OFFSHORE THE MID-
ATLANTIC/NEW ENGLAND COAST BY WEDNESDAY.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MOST GUIDANCE IS FAIRLY AGREEABLE WITH THE LARGE SCALE UPPER FLOW
PATTERN DURING THE PERIOD, BUT CONTINUE TO SHOW DIFFERENCES IN THE
DETAILS AND TIMING OF SYSTEMS. THERE CONTINUES TO BE TIMING
DIFFERENCES WITH THE SHORTWAVE THROUGH THE MIDWEST-EAST
TUESDAY/WEDNESDAY WITH THE CMC ON THE SLOW SIDE, AND GFS SLIGHTLY
FAST. PREFER A SOLUTION CLOSER TO THE ECMWF OR UKMET WHICH ARE MORE
IN THE MIDDLE. BY THURSDAY, GUIDANCE CONTINUES TO DIVERGE FOR THE
STORM FORECAST TO TRACK OFFSHORE THE PACIFIC NORTHWEST AND
AMPLITUDE OF THE UPPER TROUGH NEARING THE WEST COAST WITH GFS RUNS
CONTINUING TO BE FLATTER WITH THE UPPER TROUGH THAN MOST OTHER
GUIDANCE. THIS SPREAD EXPANDS INLAND ACROSS THE WESTERN HALF OF THE
COUNTRY DURING FRIDAY- SATURDAY. GFS RUNS REMAIN ON THE HIGH SIDE
OF THE SPREAD FOR HEIGHTS ALOFT WITH MOST OTHER GUIDANCE SHOWING
BETTER DEFINED SHORTWAVE ENERGY BUT WITH INCREASING SPREAD FOR
DETAILS. THIS TEMPERS CONFIDENCE IN THE EXACT DETAILS OF LOW
PRESSURE THAT SHOULD REACH THE CENTRAL U.S. TOWARD THE END OF THE
WEEK. AS A RESULT OF THESE WESTERN U.S. DIFFERENCES, THE GFS TENDS
TO LEAN ON THE SLOWER SIDE OF THE SPREAD FOR THE SOUTHERN STREAM
SHORTWAVE FORECAST TO REACH INTO THE SOUTHERN PLAINS BY FRIDAY. TO
NOTE, THE NEW 12Z RUN OF THE GFS TODAY (WHICH WAS AVAILABLE AFTER
THE WPC FORECAST WAS GENERATED), DID TREND SLIGHTLY FASTER WITH THE
SOUTHERN PLAINS WAVE AND SHARPER WITH THE WESTERN TROUGH.
THE WPC FORECAST TODAY LEANED MORE HEAVILY ON THE ECMWF EARLY
PERIOD, WITH LESSER CONTRIBUTIONS FROM OTHER DETERMINISTIC
GUIDANCE. TRENDED TOWARDS 70 PERCENT OF THE ENSEMBLE MEANS (WITH
THE ECMWF) LATE IN THE PERIOD TO MITIGATE THE DIFFERENCES OUT WEST.
THIS MAINTAINED GOOD CONTINUITY WITH THE PREVIOUS WPC FORECAST AS
WELL.
..WEATHER/HAZARDS HIGHLIGHTS
THE DAYS 4-5 EXCESSIVE RAINFALL OUTLOOKS COVERING THE PERIOD FROM
TUESDAY THROUGH WEDNESDAY NIGHT CURRENTLY DEPICT NO RISK AREAS BUT
THERE ARE A COUPLE REGIONS OF INTEREST FOR CONTINUED MONITORING.
DURING DAY 4 THERE ARE SOME GUIDANCE SIGNALS FOR LOCALIZED HEAVY
RAINFALL POTENTIAL OVER AND WEST/NORTHWEST OF THE ARKLATEX REGION,
FOCUSED BY A COUPLE FRONTAL BOUNDARIES AND WITH INCREASING
AFTERNOON INSTABILITY. DRIER THAN AVERAGE GROUND CONDITIONS AND
SMALL-SCALE NATURE OF THIS ACTIVITY HAVE FAVORED NO RISK THUS FAR,
BUT IMPROVED CLUSTERING ON THE HEAVIER SIDE OF THE RANGE COULD
EVENTUALLY MERIT AN AREA. THEN ON DAY 5 THE PACIFIC SYSTEM
AFFECTING THE WEST COAST MAY BRING A BRIEF PERIOD OF ENHANCED
RAINFALL TO THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA COAST.
THERE IS CONTINUED SPREAD WITH MAGNITUDE AND COVERAGE (THOUGH WITH
MOST GUIDANCE SUGGESTING HIGHER AMOUNTS EXTENDING FARTHER SOUTH
THEN GFS RUNS) WHILE FIRST-GUESS GUIDANCE IS FAIRLY MUTED WITH ITS
EXCESSIVE RAINFALL POTENTIAL FOR THE TIME BEING. AGAIN WILL MONITOR
GUIDANCE FOR IMPROVED CLUSTERING HERE.
EXPECT THE SOUTHERN TIER SHORTWAVE NEARING THE SOUTHERN PLAINS
AFTER MIDWEEK TO START GENERATING RAINFALL NEAR THE RIO GRANDE
VALLEY ON WEDNESDAY WITH HEAVIER ACTIVITY LIKELY REACHING EASTWARD
MORE INTO TEXAS BY THURSDAY. GIVEN DRY SOIL CONDITIONS, MUCH OF
THIS WILL BE BENEFICIAL RAIN BUT HIGHER RATES OVER MORE URBANIZED
AREAS MAY SPUR A LOCAL THREAT. PRECIPITATION SHOULD PUSH ACROSS THE
WEST LATE IN THE WEEK, WITH LEADING GULF INFLOW HELPING TO
INCREASE THE COVERAGE AND INTENSITY OF PRECIPITATION OVER THE
PLAINS/EAST- CENTRAL U.S. BY FRIDAY- SATURDAY. MOST OF THIS
PRECIPITATION SHOULD BE RAIN BUT SOME WINTRY WEATHER WILL BE
POSSIBLE NEAR THE CANADIAN BORDER.
EARLIER IN THE PERIOD, A WEAK WAVE THAT SHOULD TRACK FROM THE
MIDWEST TO OFFSHORE THE MID-ATLANTIC/NEW ENGLAND COAST TUESDAY-
WEDNESDAY MAY PRODUCE A BAND OF MOSTLY LIGHT PRECIPITATION ALONG
ITS PATH. THE MAJORITY OF THIS ACTIVITY SHOULD BE RAIN, THOUGH A
LITTLE SNOW IS POSSIBLE ON THE NORTHERN FRINGE OF THE MOISTURE BAND
AND IN THE APPALACHIANS.
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 DURING TUESDAY-WEDNESDAY. SOME PLACES OVER THE DESERT
SOUTHWEST COULD GET CLOSE TO 100 DEGREES. 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. THE EAST WILL SEE INCREASING COVERAGE OF HIGHS 10-20F ABOVE
NORMAL BY FRIDAY-SATURDAY AFTER NEAR TO SLIGHTLY BELOW NORMAL
READINGS TUESDAY-THURSDAY.
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page