345
FXUS02 KWBC 310630
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
230 AM EDT THU OCT 31 2024
VALID 12Z SUN NOV 03 2024 - 12Z THU NOV 07 2024
...MULTI-DAY HEAVY RAIN/FLOODING THREAT FROM THE SOUTHERN PLAINS
TO THE MID-MISSISSIPPI VALLEY THIS WEEKEND INTO EARLY NEXT WEEK...
..GENERAL OVERVIEW
THE FIRST HALF THE EXTENDED PERIOD IS SHAPING UP TO BE WET ACROSS
THE SOUTH-CENTRAL U.S. WITH RETURN GULF OF MEXICO INFLOW IN A
DEEPENING MOISTURE CHANNEL BETWEEN A EAST/SOUTHEAST UPPER RIDGE AND
SLOW APPROACH OF AMPLIFIED UPPER TROUGH/LOW ENERGY AND FRONT FROM
THE WEST. THE UPPER TROUGH ENERGY IS EXPECTED TO DIG SHARPLY
ACROSS THE WESTERN U.S. THIS WEEKEND YIELDING MODERATE RAINS AND
HIGH ELEVATION SNOWS FROM THE NORTHWEST SOUTHWARD TO CALIFORNIA.
ACTIVITY SHOULD SPREAD MORE MODESTLY TO THE SOUTHWEST AND THE
INTERMOUNTAIN WEST/ROCKIES BY EARLY NEXT WEEK WITH SLOW AND
AMPLIFIED FLOW TRANSLATION AND ENERGY REINFORCEMENT AND CLOSED LOW
DEVELOPMENT AT THE BASE OF THE UPPER TROUGH/FRONTS.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST CYCLE OF THE MODELS AND ENSEMBLE CONTINUE TO BE FAIRLY
CLUSTERED WITH THE OVERALL PATTERN. A MORE AMPLIFIED UPPER FLOW
PATTERN WILL BE EVOLVING WITH A DEEP WESTERN U.S. TROUGH AND A
BUILDING RIDGE AXIS EAST OF THE MISSISSIPPI RIVER. THIS WILL RESULT
IN A PRONOUNCED TEMPERATURE DICHOTOMY ACROSS THE COUNTRY, WITH
HIGHS RUNNING UP TO 20 DEGREES ABOVE EARLY NOVEMBER AVERAGES ACROSS
THE OHIO VALLEY EARLY NEXT WEEK, AND 15 DEGREES BELOW AVERAGE FOR
PORTIONS OF THE INTERMOUNTAIN WEST. TOWARDS THE END OF THE PERIOD, THE
MODELS STILL HAVE GREAT AGREEMENT WITH THE RIDGE NEAR THE EAST
COAST, BUT VARY MORE ACROSS THE NORTH- CENTRAL U.S. AS THE MAIN
TROUGH BEGINS LIFTING OUT AND THE SECOND ONE FROM THE PACIFIC
NORTHWEST MOVES INLAND. BY UTILIZING A COMPOSITE MODEL BLEND IT
HELPED REDUCE LINGERING INDIVIDUAL SYSTEM TIMING ISSUES TO OFFER A
SEEMINGLY REASONABLE FORECAST STARTING POINT, GENERALLY IN LINE
WITH THE NATIONAL BLEND OF MODELS AND THREAT MESSAGING CONTINUITY.
WPC USED A COMBINATION OF THE NBM, 00Z ECWMF/GFS/CMC/UKMET/GEFS
MEAN/EC ENSEMBLE MEAN.
..WEATHER/HAZARDS HIGHLIGHTS
WITH A NEARLY CONTINUOUS PLUME OF DEEP-LAYERED RETURN FLOW FROM
THE GULF WEDGING BETWEEN THE AMPLIFYING WESTERN TROUGH AND THE
RIDGE ANCHORED OVER THE SOUTH/SOUTHEAST, A MULTI-DAY HEAVY RAIN
EVENT WILL LIKELY BE IN STORE FROM THE SOUTHERN PLAINS AND MID-
MISSISSIPPI VALLEY. THE WPC DAY 4/SUNDAY AND DAY 5/MONDAY
EXCESSIVE RAINFALL OUTLOOKS (EROS) CONTINUE TO OFFER MARGINAL AND
SLIGHT RISK THREAT AREAS GIVEN CONSISTENT GUIDANCE SIGNALS.
EXPECT ACTIVITY TO EXPAND AND FOCUS ALONG A SOUTHWEST TO NORTHEAST
AXIS AHEAD OF ADDITIONAL FRONTAL BOUNDARIES THIS WEEKEND AND INTO
EARLY NEXT WEEK AS ROBUST UPPER TROUGH/CLOSED LOW ENERGY DIGS
UPSTREAM INTO THE WEST COAST TO RE- AMPLIFY THE FLOW OVER THE LOWER
48 AND VICINITY. MULTIPLE DAYS OF SOUTHERLY, MOIST GULF INFLOW
LOOK TO INCREASE THE CHANCES OF MORE WIDESPREAD, HEAVY RAINFALL
WITH FLOODING CONCERNS DESPITE DRY ANTECEDENT CONDITIONS, WITH A
RISK OF REPEAT/TRAINING CONVECTION IN A SLOW TO DISLODGE AND
DEEPENED MOISTURE CHANNEL BETWEEN THE WEST/SOUTHWEST U.S. UPPER
TROUGH AND EAST/SOUTHEAST U.S. WARMING UPPER RIDGE. IF THE HEAVY
RAINS ON DAY 5 TREND HEAVIER, OR APPEARS LIKELY TO FALL ON THE SAME
AREAS THAT GET IMPACTFUL RAIN IN THE PRECEDING DAYS, AN EVENTUAL
MODERATE RISK COULD BE NEEDED AS THE EVENT GETS CLOSER IN TIME. THE
MULTI- DAY THREAT WILL LIKELY CONTINUE INTO EARLY NEXT WEEK WHILE
SPREADING NORTHEASTWARD OVER THE MIDWEST IN THIS PATTERN WITH THE
DEEP MOISTURE LEADING TO SOME WARM SECTOR RECORD HIGH OVERNIGHT
TEMPERATURES.
FOR THE PACIFIC NORTHWEST PRECIPITATION STREAMING THIS WEEKEND
WILL LIKELY SEE LOCAL ENHANCEMENT ALONG WITH HIGH-ELEVATION SNOW
REACHING THE INTERMOUNTAIN WEST/ROCKIES WHILE ENHANCING RAINS
DOWN INTO CALIFORNIA. COOLER TEMPERATURES WILL FILTER IN ACROSS THE
WEST WHICH WILL HELP SPREAD RAIN INTO THE SOUTHWEST AND INTO THE
SOUTH-CENTRAL GREAT BASIN AND ROCKIES INTO EARLY NEXT WEEK.
MEANWHILE, ADDITIONAL PACIFIC SYSTEM ENERGY UPSTREAM MAY ALSO BRING
ANOTHER ROUND OF MODERATE PRECIPITATION BACK INTO THE NORTHWEST.
CAMPBELL/HAMRICK/SCHICTEL
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.PHPSCHICHTEL/HAMRICK
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