923
FXUS02 KWBC 070700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 AM EST WED FEB 07 2024
VALID 12Z SAT FEB 10 2024 - 12Z WED FEB 14 2024
..OVERVIEW
AN UPPER SHORTWAVE/POSSIBLE COMPACT CLOSED LOW OVER THE SOUTHWEST
SHOULD MOSTLY HOLD THROUGH THE REGION BEFORE BEGINNING TO SHIFT
EASTWARD WITH TIME ACROSS THE SOUTHERN TIER OF THE U.S. AS UPPER
RIDGING TRIES TO BUILD BACK OVER THE NORTHWEST. THIS WILL
INITIALLY BRING SOME MOUNTAIN SNOWS TO PARTS OF THE FOUR CORNERS
REGION, BUT THE OVERALL GENERAL PATTERN CONTINUES TO FAVOR
INCREASING RAINFALL POTENTIAL DOWNSTREAM ACROSS THE
MID-SOUTH/SOUTHEAST THIS WEEKEND, AND POSSIBLE EVENTUAL LIFTING OF
A DEEPENING EAST COAST TO WESTERN ATLANTIC CYCLONE. STRONG UPPER
RIDGING AHEAD OF THIS SYSTEM WILL SUPPORT MUCH ABOVE NORMAL
TEMPERATURES AS WELL ACROSS THE EAST THROUGH SUNDAY, WHILE PERIOD
ENERGY INTRUSIONS INTO THE WESTERN RIDGE BRINGS GENERALLY LIGHT
PRECIPITATION TO PARTS OF THE PACIFIC NORTHWEST. BY THE MIDDLE OF
NEXT WEEK, THE FLOW ACROSS THE CONUS SHOULD TURN MORE ZONAL
BRINGING CALM AND MOSTLY DRY CONDITIONS TO MUCH OF THE COUNTRY.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THERE REMAINS GOOD AGREEMENT ON THE OVERALL PATTERN EVOLUTION
ACROSS THE CONUS DURING THE PERIOD, BUT PLENTY OF UNCERTAINTY IN
THE DETAILS AND TIMING OF INDIVIDUAL SYSTEMS. THE SYSTEM OF
GREATEST INTEREST, WITH THE MOST SENSIBLE WEATHER IMPLICATIONS, IS
THE POTENT SHORTWAVE EXITING THE SOUTHWEST INTO THE SOUTHERN U.S.
THIS WEEKEND/EARLY NEXT WEEK. COMPARED TO PRIOR RUNS, THERE HAS
BEEN SOME NARROWING OF THE FORECAST SPREAD FOR THIS SYSTEM, BUT
STILL SOME KEY DIFFERENCES IN THE TIMING OF THIS SYSTEM THROUGH
THE SOUTHEAST MONDAY-TUESDAY. YESTERDAY'S 12Z ECMWF WAS A CLEAR
VERY SLOW OUTLIER COMPARED TO THE REST OF THE DETERMINISTIC
GUIDANCE/ENSEMBLE MEANS, BUT IT'S NEW 00Z RUN TONIGHT CAME IN
BETTER LINE WITH CONSENSUS. SOME RUN TO RUN VARIABILITY, BUT THE
GFS HAS ACTUALLY BEEN THE MOST CONSISTENT WITH THIS SYSTEM THE
PAST DAY OR SO. EVEN WITH THE NEWEST 00Z RUNS TONIGHT, THERE
REMAINS UNCERTAINTY IN THE TIMING, STRENGTH, AND EXACT TRACK OF
THIS SYSTEM, BUT OVERALL THERE SEEMS TO BE MORE AGREEMENT WHICH
BOLSTERS FORECAST CONFIDENCE SOMEWHAT. THERE WAS ENOUGH AGREEMENT
FOR THIS WEEKEND TO USE A PURELY DETERMINISTIC MODEL BLEND FOR THE
WPC FORECAST FOR TONIGHT, BUT DID USE A NON-ECMWF BLEND FOR THE
LATER PERIODS WITH THE ENSEMBLE MEANS. THIS MAINTAINED GOOD
CONTINUITY WITH THE PREVIOUS WPC FORECAST.
..WEATHER/HAZARDS HIGHLIGHTS
GENERAL BROAD TROUGHING OVER THE SOUTHWEST SHOULD KEEP THE WESTERN
U.S. PERIODICALLY ACTIVE WITH WIDESPREAD LOWER ELEVATION
RAIN/MOUNTAIN SNOWS THROUGH SATURDAY WITH THE BEST SNOW POTENTIAL
SHOULD BE OVER THE FAVORED TERRAIN OF THE FOUR CORNERS STATES.
PRECIPITATION MAY CLEAR OUT OF MUCH OF THE INTERMOUNTAIN WEST BY
SUNDAY, BUT ONE OR MORE PROGRESSIVE SYSTEMS COULD BRING EPISODES
OF LIGHT TO MODERATE TOTALS TO THE PACIFIC NORTHWEST.
A TRAILING COLD FRONT SHOULD FOCUS MOISTURE AND SOME INSTABILITY
TO PRODUCE RAIN ACROSS THE MID-SOUTH THIS WEEKEND AIDED BY
SHORTWAVE ENERGY OUT OF THE SOUTHWEST. THIS MAY INCREASE POTENTIAL
FOR TRAINING/REPEAT SHOWERS AND THUNDERSTORMS OVER SOME AREAS, BUT
WITH STILL A LOT OF SPREAD IN THE DETAILS AND CORRESPONDING
LOCATION/MAGNITUDE/TIMING OF THE HEAVIEST RAINFALL. ENSEMBLES
SUGGEST THE PRIMARY REGION THAT REQUIRES MONITORING EXTENDS FROM
THE LOWER MISSISSIPPI VALLEY INTO THE TENNESSEE
VALLEY/SOUTHEAST/GULF COAST WHERE SOIL MOISTURE VALUES ARE ABOVE
NORMAL IN SOME PLACES. THERE WAS ENOUGH CONSENSUS IN THE GUIDANCE
FOR THE INTRODUCTION OF A MARGINAL RISK ACROSS THE GENERAL REGION
ON BOTH THE DAY 4/SATURDAY AND DAY 5/SUNDAY EXCESSIVE RAINFALL
OUTLOOKS. MEANWHILE, THE FAR NORTHERN FRINGE OF THE MOISTURE
SHIELD COULD PRODUCE SOME SNOW FROM THE WEEKEND INTO EARLY NEXT
WEEK, BUT HIGHLY UNCERTAIN AND DEPENDENT ON THE EXACT TRACK OF THE
VERY UNCERTAIN LOW PRESSURE SYSTEM OUT OF THE SOUTH-CENTRAL
STATES. THERE IS WITH THE PAST GUIDANCE CYCLE SOME TREND TOWARD
LOW DEVELOPMENT UP AND OFF THE EAST COAST INTO MONDAY AND TUESDAY,
ALBEIT MAINLY CONTINGENT ON STILL UNCERTAIN STREAM PHASINGS. THIS
TYPE OF SCENARIO DOES OFFER MORE POTENTIAL FOR LIFTING/WRAPPING
RAINS WITH FOCUS UP THE MID-ATLANTIC AND SOME WINDOW FOR SNOW FOR
MARGINALLY COOLER AREAS FROM THE APPALACHIANS THROUGH THE INTERIOR
NORTHEAST.
THE UPPER RIDGE PROGRESSING FROM THE EASTERN U.S. INTO THE WESTERN
ATLANTIC LATE THIS WEEK WILL SUPPORT A BROAD AREA OF UNSEASONABLY
WARM TEMPERATURES ACROSS THE OHIO VALLEY/EAST COAST. DEPARTURES
FROM NORMAL SHOULD EVENTUALLY BECOME SOMEWHAT LESS EXTREME WITH
TIME BUT DAYTIME HIGHS ON SATURDAY COULD BE 10-20+ ABOVE NORMAL,
WITH SOME POTENTIAL FOR DAILY TEMPERATURE RECORDS. IN CONTRAST,
THE SOUTHWEST U.S./CALIFORNIA SHOULD BE PERSISTENTLY COOL,
ESPECIALLY FOR DAYTIME HIGHS THAT MAY BE UP TO 10-15F BELOW NORMAL
INTO THE WEEKEND. THIS REGION SHOULD BEGIN TO SEE A MODERATING
TREND BY SUNDAY OR MONDAY. CLOUDS/PRECIPITATION OVER THE WEST
SHOULD KEEP MOST MORNING LOWS WITHIN A FEW DEGREES ON EITHER SIDE
OF NORMAL BUT A FEW LOCALIZED COOLER SPOTS ARE POSSIBLE. BY
TUESDAY-WEDNESDAY, MUCH OF THE CONUS SHOULD BE NEAR OR WITHIN A
FEW DEGREES OF NORMAL AS MORE ZONAL FLOW EVOLVES.
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, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY
MESSAGES ARE AT:
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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