087
FXUS02 KWBC 270657
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
157 AM EST MON JAN 27 2025
VALID 12Z THU JAN 30 2025 - 12Z MON FEB 03 2025
***HEAVY RAIN AND STRONG THUNDERSTORMS EXPECTED ACROSS THE
SOUTHERN U.S. TO CLOSE OUT THE WORK WEEK***
..GENERAL OVERVIEW
THE FORECAST PERIOD BEGINS THURSDAY WITH A CUT OFF UPPER LOW
EJECTING SLOWLY EASTWARD FROM THE SOUTHERN ROCKIES TO THE WESTERN
HIGH PLAINS, AND THIS WILL SUSTAIN A SURFACE LOW THAT IS EXPECTED
TO TRACK FROM TEXAS AND EVENTUALLY TO THE EAST COAST BY SATURDAY.
THIS IS EXPECTED TO FUEL THE DEVELOPMENT OF NUMEROUS SHOWERS AND
SOME STRONG/SEVERE THUNDERSTORMS ON THURSDAY ACROSS PORTIONS OF
THE DEEP SOUTH TO CLOSE OUT THE WEEK. BACK ACROSS THE PACIFIC
NORTHWEST, A COLD FRONT AND ASSOCIATED MOISTURE FEED AHEAD OF IT
WILL LEAD TO THE RETURN OF RAIN AND MOUNTAIN SNOW BY FRIDAY AND
CONTINUING INTO THE WEEKEND. BY NEXT MONDAY, AN ARCTIC AIRMASS
SETTLES SOUTHWARD ACROSS THE NORTHERN PLAINS BEHIND A STRONG COLD
FRONT, WHILE MOST OF THE U.S. HAS A RETURN TO WARMER TEMPERATURES.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 18/00Z MODEL GUIDANCE SUITE IS IN GOOD SYNOPTIC SCALE
AGREEMENT ACROSS THE COUNTRY FOR THE END OF THE WEEK, AND A GENERAL
DETERMINISTIC MODEL BLEND SUFFICES AS A STARTING POINT IN THE
FORECAST PROCESS. THERE HAS BEEN A NOTABLE TREND FOR A MUCH FASTER
PROGRESSION OF THE LOW PRESSURE SYSTEM CROSSING THE SOUTHERN TIER
STATES, AND IS EASILY SEVERAL HUNDRED MILES FASTER THAN EARLIER
FORECASTS SINCE THE UPPER LOW IS PROGGED TO GET DISLODGED QUICKER
AND BECOME ABSORBED BY THE WESTERLIES. EVEN THOUGH THE GUIDANCE IS
IN GOOD AGREEMENT ON THIS SCENARIO, FUTURE ADJUSTMENTS IN TIMING
ARE VERY LIKELY GIVEN THE RECENT TRENDS.
GIVEN THE TRANSITION TO A MORE ZONAL FLOW PATTERN ALOFT BY SUNDAY
AND INTO MONDAY, THE GUIDANCE DIFFERS MORE WITH TIMING AND
MAGNITUDE OF FEATURES IN THE NORTHERN STREAM FLOW, AND THE ARRIVAL
OF THE ARCTIC FRONT ACROSS THE NORTHERN PLAINS. THE FORECAST BLEND
TRANSITIONED TO ABOUT 50% ENSEMBLE MEANS BY MONDAY TO ACCOUNT FOR
THE INCREASING MODEL UNCERTAINTY.
..WEATHER/HAZARDS HIGHLIGHTS
A SLOW MOVING OCCLUDED LOW PRESSURE SYSTEM IS FORECAST TO MOVE
ACROSS THE SOUTHERN PLAINS THURSDAY AND THEN ACROSS THE DEEP SOUTH
AND TENNESSEE RIVER VALLEY ON FRIDAY. IN THE WARM SECTOR OF THE
SURFACE LOW, WARM AIR ADVECTION IN COMBINATION WITH STRONG FORCING
ALOFT WILL CREATE A FAVORABLE ENVIRONMENT FOR HEAVY RAINFALL FROM
THE ARKLATEX REGION TO THE MID SOUTH. THERE WILL LIKELY BE A
CORRIDOR OF 2 TO 4 INCH RAINFALL TOTALS ACROSS PORTIONS OF THIS
REGION, AND THERE COULD BE THE POTENTIAL FOR TRAINING/REPEATED
CONVECTION AHEAD OF THE SLOW TRAILING COLD FRONT. THEREFORE, A
SLIGHT RISK IS PLANNED FOR DAY 4 FROM NORTHEAST TEXAS TO NEAR THE
GREATER MEMPHIS AREA, AND THIS HAS BEEN ADJUSTED ABOUT 50-100
EASTWARD COMPARED TO THE PREVIOUS DAY 5 OUTLOOK. FOR THE NEW DAY 5
OUTLOOK, A MARGINAL RISK AREA IS PLANNED FROM EXTREME NORTHWEST
CALIFORNIA TO THE OLYMPIC PENINSULA OF WASHINGTON WHERE A POTENTIAL
ATMOSPHERIC RIVER EVENT COULD LEAD TO SOME PERIODS OF HEAVIER
RAINFALL ON FRIDAY. THIS IS EXPECTED TO CONTINUE INTO THE WEEKEND
AS WELL WITH ADDITIONAL MOIST ONSHORE FLOW.
A PERIOD OF DRY WEATHER IS EXPECTED FOR THE OHIO VALLEY AND INTO
THE NORTHEAST BEFORE PRECIPITATION ASSOCIATED WITH THE OCCLUDED
LOW REACHES THE AREA. PRECIPITATION CHANCES WILL EXTEND TO THE
NORTH OF THE OCCLUDED SYSTEM, AND THERE WILL BE A CHANCE FOR
SNOW/ICE ON THE NORTHERN EXTENT OF THE PRECIPITATION SHIELD GIVEN
LINGERING COLD AIR IN PLACE. WINTRY WEATHER IS ALSO ANTICIPATED ON
THE BACKSIDE OF THAT SAME LOW ON THURSDAY, AND HEAVY SNOW/ICE WILL
BE POSSIBLE IN NORTHERN NEW MEXICO AND SOUTHERN COLORADO AND
ADJACENT PORTIONS OF KANSAS AND THE OK/TX PANHANDLES.
TEMPERATURES ARE EXPECTED TO BE PLEASANTLY MILD TO CLOSE OUT THE
WEEK FOR THIS TIME OF YEAR ACROSS MUCH OF THE CENTRAL AND EASTERN
U.S., WITH HIGHS RUNNING ABOUT 5-15 DEGREES ABOVE AVERAGE IN MOST
CASES, AND PERHAPS 20+ DEGREES ABOVE AVERAGE ACROSS PARTS OF THE
UPPER MIDWEST ON THURSDAY. THIS ALSO HOLDS TRUE GOING INTO THE
WEEKEND, ALTHOUGH NEW ENGLAND AND THE MID-ATLANTIC REGION LIKELY
REMAIN CLOSER TO SEASONAL AVERAGES. THE NEXT ROUND OF ARCTIC COLD
LIKELY ARRIVES ACROSS MONTANA ON SUNDAY AND EXTENDS INTO THE
DAKOTAS BY MONDAY, WITH HIGHS POTENTIALLY 15-25 DEGREE BELOW
AVERAGE IN MANY CASES.
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 (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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