926
FXUS02 KWBC 061853
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
152 PM EST TUE FEB 06 2024
VALID 12Z FRI FEB 09 2024 - 12Z TUE FEB 13 2024
..OVERVIEW
A RELOADING UPPER TROUGH POSITION SHOULD MAINLY HOLD ON OVER THE
WEST INTO THE WEEKEND, BEFORE BEGINNING TO SLOWLY SHIFT EASTWARD
AS UPPER RIDGING TRIES TO BUILD IN NEAR THE WEST COAST AGAIN AND A
COUPLE OF ORGANIZED SYSTEMS PUSH THROUGH THE EAST PACIFIC. THE
TROUGH WILL CONTINUE TO KEEP THIS REGION ACTIVE WITH ROUNDS OF
LOWER ELEVATION RAINS AND MOUNTAIN SNOW. MEANWHILE, A STRONG UPPER
RIDGE SHIFTING OUT OF THE CENTRAL U.S. WILL CONTINUE TO SUPPORT
WELL ABOVE NORMAL TEMPERATURES THAT COULD BE RECORD-SETTING ACROSS
THE PARTS OF THE UPPER GREAT LAKES-NORTHEAST ON FRIDAY-SATURDAY
BEFORE IT BECOMES SUPPRESSED AND SHIFTS EASTWARD OFF THE COAST. A
FAIRLY STRONG STORM SYSTEM TRACKING OUT OF THE GREAT LAKES ON
FRIDAY WILL PRODUCE SOME COLD SECTOR SNOW AND BRISK WINDS. THEN
ADDITIONAL SHORTWAVES/ENERGY FROM THE MEAN UPPER TROUGH OVER THE
WEST WILL PERIODICALLY EJECT INTO THE CENTRAL U.S. THERE IS
SIGNIFICANT UNCERTAINTY OVER HOW ASSOCIATED SYSTEMS WILL REFLECT
AT THE SURFACE TO THE EAST OF THE ROCKIES, BUT THE GENERAL PATTERN
APPEARS FAVORABLE FOR INCREASING RAINFALL ACROSS THE
MID-SOUTH/SOUTHEAST BY LATE WEEK/WEEKEND PRIOR TO A POTENTIAL
LIFTING OF A DEEPENING EAST COAST TO WESTERN ATLANTIC LOW TO
MONITOR FOR INTO EARLY NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THERE HAS BEEN SOME NARROWING OF FORECAST SPREAD ACROSS THE LOWER
48 AND VICINITY INTO THE WEEKEND, BOLSTERING FORECAST SPREAD. THE
GFS/ECMWF/UKMET SOLUTIONS SEEM BEST CLUSTERED IN THIS PERIOD AND
ENSEMBLE SUPPORT IN A FAVORED MODEL COMPOSITE IS REASONABLE.
FORECAST SPREAD AND GROWING UNCERTAINTIES WITH EMBEDDED SYSTEM
DETAILS AND THE DEGREE OF POTENTIAL PHASING OF NORTHERN AND
SOUTHERN STREAM ENERGIES OVER TIME STILL NEED TO BE WORKED OUT FOR
INTO EARLY NEXT WEEK. THE 00 UTC RUN CYCLE WAS TRENDING IN A
COMMON DIRECTION WITH PHASING, BUT 12 UTC MODELS DO NOT OFFER
STELLAR RUN TO RUN CONTINUITY WITH A TREND AWAY FROM PHASING.
..WEATHER/HAZARDS HIGHLIGHTS
GENERAL BROAD TROUGHING OVER THE SOUTHWEST SHOULD KEEP THE WESTERN
U.S. PERIODICALLY ACTIVE WITH WIDESPREAD LOWER ELEVATION
RAIN/MOUNTAIN SNOWS INTO NEXT WEEKEND. BEST SNOW POTENTIAL SHOULD
BE OVER THE FAVORED TERRAIN OF THE FOUR CORNERS STATES. ADDITIONAL
ROUNDS OF RAIN AND MOUNTAIN SNOWS COULD COME INTO CALIFORNIA
THROUGH FRIDAY, THOUGH WITH VERY LOW CONFIDENCE ON EXACT AMOUNTS
AND LOCATIONS OF HEAVIEST PRECIPITATION. GIVEN EXTREME RAINFALL
ACROSS MUCH OF CALIFORNIA RECENTLY, THE AREA IS MORE SENSITIVE
THAN USUAL TO ADDITIONAL RAINFALL, BUT THE FACT THAT ANY DIGGING
DYNAMICS ALOFT SHOULD TAKE AN ALONG-COAST OR INLAND PATH SHOULD
NOT BE SUPPORTIVE OF A HEAVY PRECIPITATION THREAT. PRECIPITATION
MAY CLEAR OUT OF MUCH OF THE INTERMOUNTAIN WEST BY SATURDAY, BUT
ONE OR MORE PROGRESSIVE SYSTEMS COULD BRING EPISODES OF LIGHT TO
MODERATE TOTALS TO THE PACIFIC NORTHWEST.
FAIRLY STRONG LOW PRESSURE WILL BE TRACKING OUT OF THE GREAT LAKES
FRIDAY INTO SATURDAY, THOUGH WITH STILL SOME LINGERING SNOW AND
GUSTY WIND THREAT ON THE BACKSIDE OF THE SYSTEM. THE TRAILING COLD
FRONT SHOULD FOCUS MOISTURE AND SOME WEAK INSTABILITY TO PRODUCE
RAIN ACROSS THE MID-SOUTH LATE WEEK, BUT ESPECIALLY INTO THE
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 TENNESSEE VALLEY INTO LOWER MISSISSIPPI VALLEY
AND SOUTHEAST. THIS OVERALL AREA HAS A MIX OF ANTECEDENT SOIL
MOISTURE CONDITIONS. DESPITE THE PRESENCE OF ANAMOLOUS MOISTURE
AND SOME INSTABILITY, CONFIDENCE REMAINS TOO LOW THOUGH TO
INTRODUCE ANY RISK AREAS IN THE DAYS 4-5 EROS AT THIS TIME, BUT
AGAIN THE GENERAL PATTERN MAY ULTIMATELY SUPPORT AN AXIS OF HEAVY
RAINFALL SOMETIME IN THE WEEKEND TIME FRAME. MEANWHILE, THE FAR
NORTHERN FRINGE OF THE SOUTHERN TIER 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. ACCORDINGLY, LATEST
WPC PROGS NOW SHOW A MORE ORGANIZED LOW TRACK, BUT NOT TO THE
EXTENT OF SOME OF THE LATEST MODELS. 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 WHICH WILL GRADUALLY SHIFT FROM THE GREAT
LAKES/MIDWEST TOWARD THE EAST COAST. DEPARTURES FROM NORMAL SHOULD
EVENTUALLY BECOME SOMEWHAT LESS EXTREME WITH TIME. THE UPPER
MIDWEST/GREAT LAKES SHOULD BE WARMEST VERSUS NORMAL ON FRIDAY WITH
ANOMALIES UP TO PLUS 30F FOR MORNING LOWS AND PLUS 25F FOR DAYTIME
HIGHS, LEADING TO WIDESPREAD DAILY TEMPERATURE RECORDS. BY THE
WEEKEND EXPECT THE EAST TO SEE LOWS OF 15-30F ABOVE NORMAL AND
HIGHS 10-20F ABOVE NORMAL WHILE THE CENTRAL U.S. TRENDS CLOSER TO
NORMAL. 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.
SANTORELLI/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, 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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