170
FXUS02 KWBC 211900
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 PM EST TUE JAN 21 2025
VALID 12Z FRI JAN 24 2025 - 12Z TUE JAN 28 2025
..OVERVIEW
MEAN TROUGHING OVER THE EAST-CENTRAL U.S. ON FRIDAY WILL PROGRESS
EASTWARD AND CROSS THE EAST COAST BY THE WEEKEND. BEHIND THIS, WEAK
RIDGING AND MORE ZONAL FLOW WILL DEVELOP, FINALLY HELPING TO
MODERATE THE BITTERLY COLD TEMPERATURES IN THE SOUTH AND EAST. A
SHORTWAVE DROPPING INTO THE NORTHERN ROCKIES LATE THIS WEEK WILL
SPLIT, SENDING NORTHERN STREAM ENERGY ACROSS THE NORTHERN TIER OF
THE NATION WHILE TRAILING ENERGY DIVES SOUTH TO FORM A CLOSED LOW
OVER THE SOUTHWEST THAT WILL LINGER THROUGH EARLY NEXT WEEK. THE
UPPER LOW WILL LIKELY BRING BENEFICIAL PRECIPITATION TO PARTS OF
SOUTHERN CALIFORNIA THAT HAVE BEEN DEALING WITH DEVASTATING
WILDFIRES. PRECIPITATION WILL ALSO BE ENHANCED ACROSS THE LOWER
MISSISSIPPI VALLEY SUNDAY AND MONDAY AS A SLOW MOVING FRONTAL
BOUNDARY MOVES THROUGH THE REGION.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE IS IN GOOD AGREEMENT ON THE OVERALL WEATHER PATTERN
THROUGH THE MEDIUM RANGE PERIOD. UNCERTAINTY SURROUNDING A
POTENTIAL UPPER LOW CLOSING OFF OVER THE SOUTHWEST THIS WEEKEND
INTO EARLY NEXT WEEK IS GRADUALLY DECREASING. THE ECMWF HAS SHOWN
THE HIGHEST RUN-TO-RUN CONSISTENCY WITH THIS FEATURE, DEPICTING THE
LOW CLOSING OFF OVER THE SOUTHWEST ON SUNDAY AND SLOWLY DRIFTING
EAST-SOUTHEAST THROUGH EARLY NEXT WEEK, AND THIS IS CONSISTENT WITH
THE ENSEMBLE MEANS FROM THE GEFS/ECENS/CMCE. THE 00Z GFS AND CMC
KEPT THE UPPER LOW FURTHER WEST, BUT THE 06Z AND 12Z RUNS HAVE
SHIFTED EASTWARDS, CLOSER TO THE ECMWF SOLUTION. THE CMC STILL
REMAINS THE OUTLIER WITH THE LOW PLACEMENT FARTHER WEST THAN THE
GENERAL CONSENSUS. THERE IS A BIT MORE UNCERTAINTY LATE IN THE
PERIOD AS A POTENTIAL SHORTWAVE DROPS INTO THE NORTHERN PLAINS OR
UPPER MIDWEST ON MONDAY AND PROGRESSES EAST ACROSS THE GREAT LAKES
OR NORTHEAST ON TUESDAY. THERE IS A SIGNIFICANT AMOUNT OF MODEL
SPREAD IN PLACEMENT AND STRENGTH OF THIS FEATURE, WHICH COULD
IMPACT THE SENSIBLE WEATHER ACROSS THE NORTHERN TIER MONDAY AND
TUESDAY.
GIVEN GOOD MODEL AGREEMENT, A NEAR EVEN BLEND OF THE 06Z GFS AND
00Z ECMWF/CMC/UKMET WAS USED FOR DAYS 3-5 (FRIDAY THROUGH SUNDAY).
FOR DAYS 6 AND 7, THE WEIGHT PLACED ON THE CMC AND UKMET WERE
DECREASED AND ENSEMBLE MEANS FROM THE GEFS AND ECENS WERE ADDED,
RESULTING IN A GOOD MIDDLE OF THE ROAD FORECAST THAT FALLS CLOSE TO
THE MEANS AND GENERAL CONSENSUS. THIS BLEND KEPT GOOD CONTINUITY
WITH WPC'S PREVIOUS FORECAST AS WELL.
..WEATHER/HAZARDS HIGHLIGHTS
COLDER THAN NORMAL TEMPERATURES WILL LINGER THROUGH FRIDAY IN THE
EAST AND THROUGH SATURDAY IN THE SOUTH AND SOUTHEAST. THE COLDEST
ANOMALIES WILL BE FOCUSED ALONG THE GULF COAST WHERE COLD COULD BE
HAZARDOUS AT NIGHT WHEN LOWS DIP BELOW FREEZING. TEMPERATURES WILL
GRADUALLY MODERATE, RETURNING TO NEAR NORMAL SUNDAY THROUGH EARLY
NEXT WEEK. ANOMALOUSLY COLD TEMPERATURES WILL ALSO DEVELOP IN THE
HIGH PLAINS, ROCKIES, AND MUCH OF THE WEST THIS WEEKEND UNDER THE
INFLUENCE OF UPPER TROUGHING. THE COLDEST ANOMALIES WILL BE IN THE
HIGH PLAINS AND ROCKIES WHERE HIGH TEMPERATURES COULD BE 10-20
DEGREES BELOW NORMAL.
PRECIPITATION WISE, A COUPLE CLIPPER SYSTEMS MAY PRODUCE SOME LIGHT
SCATTERED PRECIPITATION FROM THE NORTHERN PLAINS TO THE MIDWEST,
GREAT LAKES, OHIO VALLEY, AND NORTHEAST. MORE WIDESPREAD RAIN AND
MOUNTAIN SNOWS WILL MOVE INTO THE WEST BY THE END OF THE WEEK AS A
FRONTAL SYSTEM DROPS SOUTH ACROSS THE REGION, WHICH WILL LIKELY
PROVIDE BENEFICIAL RAIN TO SOUTHERN CALIFORNIA OVER THE WEEKEND. A
TIGHT GRADIENT BEHIND THE COLD FRONT DROPPING SOUTH MAY PRODUCE AN
EPISODE OF STRONG WINDS ALONG PARTS OF THE ROCKIES LATE THIS WEEK
AND OVER CALIFORNIA AND NEVADA ON SATURDAY. FARTHER EAST, SOME GULF
MOISTURE WILL LIKELY INTERACT WITH A FRONT APPROACHING THE LOWER
MISSISSIPPI VALLEY TO TENNESSEE AND OHIO VALLEYS BY THIS COMING
WEEKEND/EARLY NEXT WEEK. LATEST GUIDANCE CONTINUES TO TREND HEAVIER
WITH ENHANCED RAINFALL OVER PARTS OF THE SOUTHERN U.S., WITH THE
POTENTIAL FOR HEAVY RAIN AND THUNDERSTORMS ON SUNDAY ACROSS THE
LOWER MISSISSIPPI VALLEY. SNOW WILL BE POSSIBLE FARTHER NORTH
ACROSS THE GREAT LAKES, WITH A WINTRY MIX POSSIBLE ACROSS THE OHIO
VALLEY, CENTRAL APPALACHIANS, AND POTENTIALLY THE TENNESSEE VALLEY
AS WELL. PRECIPITATION MAY SPREAD TOWARDS THE EAST COAST EARLY NEXT
WEEK AS THE FRONTAL SYSTEM PROGRESSES.
DOLAN/SANTORELLI
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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