253
FXUS02 KWBC 260656
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
156 AM EST SUN JAN 26 2025
VALID 12Z WED JAN 29 2025 - 12Z SUN FEB 02 2025
..SOUTH-CENTRAL U.S. HEAVY RAINFALL THREAT WEDNESDAY-SATURDAY
..GENERAL OVERVIEW
A SLOW MOVING CLOSED UPPER LOW WILL LINGER OVER THE SOUTHWEST
WEDNESDAY AND THURSDAY, THEN GRADUALLY PUSH NORTHEAST TOWARDS THE
SOUTHERN/CENTRAL PLAINS AND MIDWEST FRIDAY AND SATURDAY. THIS
FEATURE WILL BE ACCOMPANIED BY AN OCCLUDED LOW PRESSURE SYSTEM AT
THE SURFACE THAT COULD BRING A HEAVY RAINFALL THREAT TO THE SOUTH-
CENTRAL U.S. DURING THE SECOND HALF OF THE WEEK. MEANWHILE, A BROAD
UPPER TROUGH WILL SWING ACROSS THE NORTH-CENTRAL AND NORTHEASTERN
U.S. AND RIDGING WILL EXTEND NORTH INTO THE PACIFIC NORTHWEST. BY
FRIDAY, A TROUGH WILL APPROACH THE WEST COAST AND PUSH A PACIFIC
FRONTAL SYSTEM EAST ACROSS THE WEST NEXT WEEKEND WHILE AN ARCTIC
FRONT SINKS SOUTH ACROSS THE NORTH-CENTRAL U.S..
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE IS IN GOOD AGREEMENT ON THE OVERALL PATTERN THROUGH
THE END OF THE WEEK, THEN MODEL SPREAD INCREASES FOR NEXT WEEKEND,
WHICH IS TYPICAL AT THIS TIME FRAME. DETERMINISTIC AND AI GUIDANCE
HAS TRENDED A LITTLE FASTER WITH THE CLOSED LOW MOVING ACROSS THE
SOUTHERN/CENTRAL PLAINS, WHICH IS REFLECTED IN WPCS FORECAST. THERE
IS STILL SOME UNCERTAINTY SURROUNDING THE EVOLUTION OF THE OCCLUDED
SURFACE LOW, BUT THERE IS STILL GOOD AGREEMENT FOR HEAVY RAINFALL
IN THE WARM SECTOR OF THE SYSTEM OVER THE SOUTH-CENTRAL U.S. LATER
THIS WEEK. THE MOST UNCERTAIN FEATURES ARE ON DAY 7/SUNDAY WHEN
THERE IS SIGNIFICANT SPREAD IN THE TIMING/LOCATION OF SURFACE
FEATURES. FOR NOW, A COMPROMISE NEAR THE ENSEMBLE MEAN SOLUTIONS
WAS USED FOR THE WPC FORECAST.
THE WPC FORECAST MODEL BLEND CONSISTS OF A EVEN BLEND OF THE
GFS/ECMWF/CMC/UKMET FOR WEDNESDAY AND THURSDAY. FOR FRIDAY ONWARD,
THE WEIGHT PUT ON THE CMC WAS REDUCED AS IT BECOMES MORE OF AN
OUTLIER FROM THE GENERAL CONSENSUS, THE UKMET WAS REMOVED AS IT IS
UNAVAILABLE THAT FAR OUT, AND THE GEFS AND ECENS MEANS WERE ADDED
IN INCREASING AMOUNTS. THIS BLEND MAINTAINS GOOD CONTINUITY WITH
WPC'S PREVIOUS FORECAST.
..WEATHER/HAZARDS HIGHLIGHTS
A SLOW MOVING OCCLUDED LOW PRESSURE SYSTEM IS FORECAST TO MOVE
ACROSS THE SOUTHERN PLAINS WEDNESDAY THROUGH FRIDAY WITH A COLD
FRONT EXTENDING SOUTHWEST INTO MEXICO AND A WARM FRONT LIFTING INTO
THE LOWER MISSISSIPPI VALLEY. WARM, MOIST AIR FROM THE GULF WILL
BE IN PLACE ACROSS THE SOUTH-CENTRAL U.S., SETTING THE STAGE FOR A
MULTI-DAY HEAVY RAINFALL EVENT. THE BEST CHANCE FOR HEAVY RAINFALL
WILL BE IN THE WARM SECTOR AND IN THE VICINITY OF THE TRIPLE POINT
LOW WHERE MOISTURE AND INSTABILITY WILL BE MAXIMIZED, AND THERE
COULD BE POTENTIAL FOR TRAINING CONVECTION AHEAD OF THE SLOW
TRAILING COLD FRONT. HEAVY RAINFALL COULD LEAD TO FLASH FLOODING
CONCERNS ACROSS THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY,
ESPECIALLY IN THE ARK-LA-TEX REGION ON THURSDAY AND LOUISIANA AND
MISSISSIPPI ON FRIDAY.
FOR THE DAY 4/WEDNESDAY EXCESSIVE RAINFALL OUTLOOK, THERE IS A BIT
TOO MUCH UNCERTAINTY IN RAINFALL LOCATION TO INTRODUCE ANY RISK
AREAS AT THIS TIME, BUT THERE STILL COULD BE LIMITED POTENTIAL FOR
HEAVY RAINFALL IN PORTIONS OF TEXAS. FOR THE DAY 5/THURSDAY
EXCESSIVE RAINFALL OUTLOOK, A BROAD MARGINAL RISK FROM THE SOUTHERN
PLAINS TO THE MID/LOWER MISSISSIPPI VALLEY AND A SLIGHT RISK FOR
THE ARK-LA-TEX WILL LIKELY BE NEEDED GIVEN THE STRONG SIGNAL FOR
HEAVY RAINFALL.
EARLY IN THE PERIOD, A CLIPPER TYPE LOW PRESSURE SYSTEM WILL BRING
A SWATH OF WINTRY WEATHER TO THE GREAT LAKES AND NORTHEAST, WITH
SOME LOCALIZED HEAVY SNOW POTENTIAL. THIS SYSTEM WILL QUICKLY MOVE
EAST, AND A COUPLE DAYS OF DRY WEATHER ARE EXPECTED FOR THE
NORTHERN TIER BEFORE PRECIPITATION ASSOCIATED WITH THE OCCLUDED LOW
REACHES THE AREA. PRECIPITATION CHANCES WILL EXTEND WELL TO THE
NORTH OF THE OCCLUDED SYSTEM, SPREADING TO ENCOMPASS THE EASTERN
THIRD OF THE NATION BY SATURDAY, AND THERE WILL BE A CHANCE FOR
WINTRY WEATHER ON THE NORTHERN EXTENT OF THE PRECIPITATION SHIELD
GIVEN LINGERING COLD AIR IN PLACE. WINTRY WEATHER IS ALSO
ANTICIPATED ON THE BACKSIDE OF THE LOW AS IT INITIALLY
STRENGTHENS, AND HEAVY SNOW WILL BE POSSIBLE IN NORTHERN NEW MEXICO
AND SOUTHERN COLORADO ON WEDNESDAY AND THURSDAY. BY SUNDAY, THE
SYSTEM WILL BE WEAKENING AND PRECIPITATION CHANCES WILL BE MAINLY
LIMITED TO THE GREAT LAKES AND NORTHEAST.
IN THE WEST, PRECIPITATION CHANCES WILL GRADUALLY INCREASE ACROSS
THE REGION LATE THIS WEEK INTO THE WEEKEND AS A PACIFIC FRONTAL
SYSTEM PUSHES INLAND. WIDESPREAD RAIN AND MOUNTAIN SNOW IS
EXPECTED, AND HEAVY SNOWFALL IS FORECAST FOR THE CASCADES AND
NORTHERN/CENTRAL ROCKIES.
TEMPERATURES WILL GENERALLY BE NEAR OR ABOVE NORMAL FOR MUCH OF THE
LOWER 48 LATE THIS WEEK INTO THE WEEKEND, BUT THERE WILL BE A FEW
OPPORTUNITIES FOR BELOW NORMAL TEMPERATURES. THE SOUTHWEST WILL
LIKELY BE BELOW NORMAL WEDNESDAY AND THURSDAY UNDER THE INFLUENCE
OF THE CLOSED UPPER LOW. THE NORTHEAST WILL LIKELY BE BELOW NORMAL
WEDNESDAY THROUGH FRIDAY IN AS THE CLIPPER SYSTEM MOVES THROUGH AND
COLDER AIR SINKS INTO THE REGION. FINALLY, THERE WILL BE A CHANCE
FOR WELL BELOW NORMAL TEMPERATURES IN THE NORTHERN ROCKIES AND
NORTHERN HIGH PLAINS ON SUNDAY AS AN ARCTIC FRONT SINKS SOUTH
ACROSS THE REGION.
DOLAN
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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