057
FXUS02 KWBC 270714
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
314 AM EDT SUN OCT 27 2024
VALID 12Z WED OCT 30 2024 - 12Z SUN NOV 03 2024
..MID-LATER WEEK MISSISSIPPI VALLEY HEAVY RAIN/RUNOFF THREAT
..GENERAL OVERVIEW
AN AMPLIFIED UPPER TROUGH WILL EJECT OVER THE CENTRAL U.S. MIDWEEK
BEFORE LIFTING INTO/OVERTOP A WARM AMBIENT UPPER RIDGE OVER THE
EASTERN-SOUTHEASTERN U.S.. THIS WILL RESULT IN A WAVY SHARP FRONT
THROUGH THE MID-SECTION OF THE COUNTRY WHERE A MODERATELY HEAVY
RAIN EVENT IS FORECAST FROM THE EASTERN PLAINS THROUGH THE
MISSISSIPPI VALLEY AND MIDWEST MID-LATER THIS WEEK. THE TRAILING
PORTION OF THE FRONT IS FORECAST TO SLOW AND RETREAT INTO NEXT
WEEKEND IN RESPONSE TO ROBUST RENEWED TROUGH ENERGY DIGGING INTO
AN UNSETTLED THE WEST. THIS WILL LEAD TO A RESURGENCE OF
MODERATE/HEAVY RAIN FOR THE SOUTH-CENTRAL U.S. LATE WEEK/WEEKEND.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL SOLUTIONS SEEMED REASONABLY CLUSTERED WEDNESDAY INTO EARLY
FRIDAY ACROSS MUCH OF THE NATION AND WERE IN LINE WITH THE NATIONAL
BLEND OF MODELS, ENSEMBLES AND WPC CONTINUITY IN PATTERN WITH
ABOVE NORMAL PREDICTABILITY. A COMPOSITE WAS USED IN PRODUCTION OF
THE WPC PRODUCT SUITE FOR THAT TIMEFRAME. FORECAST SPREAD INCREASED
QUICKLY LATER FRIDAY INTO NEXT WEEKEND, WITH THE 18 UTC GFS
SHOWING LESS THAN STELLAR RUN TO RUN CONSISTENCY BY BECOMING A
NOTEABLE OUTLIER FROM 12 UTC MODELS AND ENSEMBLES IN SHOWING MUCH
LESS DIGGING OF UPPER TROUGH TO CLOSED LOW ENERGY DOWN THE WEST
COAST. THE PRESENCE OF AN AMPLIFIED UPSTREAM RIDGE OVER THE EASTERN
PACIFIC AND GUIDANCE FROM THE MACHINE LEARNING AIFS RUN OF THE
ECMWF DID NOT SUPPORT THE 18 UTC GFS RUN AND IT WAS DISCOUNTED. THE
NEWER 00 UTC GFS HAS TRENDED BACK INTO THE FOLD AND OVERALL LATEST
00 UTC MODEL FORECAST SPREAD HAS DECREASED AT THESE LONGER TIME
FRAMES, HOPEFULLY PORTENDING IMPROVED FORECAST CONFIDENCE.
..WEATHER/HAZARDS HIGHLIGHTS
AHEAD OF A SHARPENING FRONT, A LONG FETCH OF RETURN FLOW FROM THE
GULF OF MEXICO APPEARS TO INITIATE AND SUPPORT A THREAT OF HEAVY
RAIN FROM THE CENTRAL/SOUTHERN PLAINS THROUGH THE MISSISSIPPI
VALLEY AND INTO THE MIDWEST WITH EMBEDDED THUNDERSTORMS MIDWEEK.
COOLING TEMPS MAY LEAD TO FROST/FREEZE BACK IN THE POST-FRONTAL
AIRMASS INTO MIDWEEK. THE TRAILING PORTION OF THE FRONT IS THEN
FORECAST TO STALL OVER THE SOUTHERN PLAINS WHERE MODERATE TO HEAVY
RAINFALL COULD LINGER AND THEN EXPAND NORTHEASTWARD BY NEXT WEEKEND
AS ROBUST UPPER TROUGH/CLOSED LOW ENERGY DIGS UPSTREAM INTO THE
WEST COAST TO RE- AMPLIFY FLOW OVER THE LOWER 48 AND VICINITY. THE
WPC DAY4 WEDNESDAY EXCESSIVE RAINFALL OUTLOOK MAINTAINED A MARGINAL
RISK AREA GIVEN POTENTIAL FOR TRAINING AND FAVORABLE UP/THURSDAY
PER TROUGH AND RIGHT ENTRANCE REGION JET DYNAMICS. THE DAY 5 ERO
DEPICTS A MARGINAL RISK AREA CENTERED OVER THE LOWER MISSISSIPPI
VALLEY WITH FRONTAL/CONVECTION AND UPPER SUPPORT PROGRESSION. IN
THE MEANTIME, PRECIPITATION ASSOCIATED WITH THE NEXT PACIFIC SYSTEM
AND LONG- FETCH MOISTURE IS FORECAST TO RE- FOCUS MODERATE
PRECIPITATION INTO THE WEST COAST LATER WEEK/WEEKEND, WITH HIGH-
ELEVATION SNOW REACHING INTO THE NORTHERN ROCKIES AND MODEST RAINS
REACHING DOWN THROUGH CALIFORNIA WITH A COLD FRONTAL SURGE AND
POSSIBLE CLOSED LOW DEVELOPMENT AT THE SOUTHERN BASE OF THE MAIN
UPPER TROUGH.
UPPER RIDGING TOGETHER WITH A PRE-FRONTAL LONG FETCH OF STRONG AND
GUSTY SOUTHERLY WINDS WILL TRANSPORT WARMTH FROM THE SOUTH THROUGH
THE NORTHEAST THROUGH MIDDLE TO LATE WEEK. HIGH TEMPERATURES WILL
THREATEN NEW DAILY RECORD HIGH TEMPERATURES BEFORE MODERATING.
SCHICHTEL
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