855
FXUS02 KWBC 050658
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
158 AM EST MON FEB 05 2024
VALID 12Z THU FEB 08 2024 - 12Z MON FEB 12 2024
..OVERVIEW
BROAD AND RENEWED TROUGHING WILL HOLD OVER THE WEST THROUGH ABOUT
SATURDAY, BEFORE BEGINNING TO SLOWLY SHIFT EASTWARD AS UPPER
RIDGING TRIES TO BUILD IN NEXT SUNDAY-MONDAY. THIS WILL KEEP THIS
REGION QUITE ACTIVE WITH ROUNDS OF LOWER ELEVATION RAINS AND
MOUNTAIN SNOW, INCLUDING POSSIBLY A COUPLE OF WEAK ATMOSPHERIC
RIVERS INTO CALIFORNIA. PRECIPITATION IS CERTAINLY FORECAST TO BE
LOWER THAN IN THE SHORT RANGE THOUGH. 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 MIDWEST ON THURSDAY-FRIDAY BEFORE IT
BECOMES SUPPRESSED AND SHIFTS EASTWARD WITH TIME.
SHORTWAVES/ENERGY FROM THE MEAN UPPER TROUGH OVER THE WEST WILL
PERIODICALLY EJECT INTO THE CENTRAL U.S., WITH A COUPLE OF
MODESTLY DEEP SURFACE LOWS MOVING INTO THE UPPER MIDWEST/GREAT
LAKES. THIS SHOULD INCREASE PRECIPITATION CHANCES ACROSS THE
MID-SOUTH/SOUTHEAST LATE PERIOD, WITH SOME SNOW CHANCES IN THE
BEGINNING OF THE PERIOD OVER THE NORTHERN PLAINS.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE CONTINUES TO BE REASONABLY AGREEABLE ON THE OVERALL
LARGE-SCALE PATTERN DURING THE MEDIUM RANGE PERIOD, BUT THERE ARE
SOME NOTABLE KEY DIFFERENCES THAT HAVE SENSIBLE WEATHER IMPACTS.
THESE DIFFERENCES MAINLY FOCUS OUT WEST INVOLVING INTEGRATION OF
MULTIPLE PIECES OF ENERGY INTO THE WESTERN TROUGH, PARTICULARLY A
POTENT SHORTWAVE WHICH SHOWS BETTER AGREEMENT TO DIG DOWN THE
WESTERN SIDE OF THE TROUGH WITH POTENTIAL COMPACT CLOSED LOW
DEVELOPING OVER THE SOUTHWEST BY SATURDAY. INITIALLY, THE GFS
SEEMED TO BE ON ITS OWN IN BEING SO AMPLIFIED WITH THIS SYSTEM,
BUT RECENTLY OTHER GUIDANCE HAS TRENDED TOWARDS THE STRONGER
SOLUTION. THERE'S STILL PLENTY OF UNCERTAINTY IN THE
DETAILS/SENSIBLE WEATHER IMPACTS, BUT OVERALL BETTER CONSENSUS FOR
A DIGGING SHORTWAVE/AMPLIFIED TROUGH WHICH EVENTUALLY SHIFTS
EASTWARD SUNDAY-MONDAY. BY THIS TIME THOUGH, THERE ARE
CONSIDERABLE DIFFERENCES IN THE TIMING WITH THE ECMWF BEING
SIGNIFICANTLY FASTER WITH THE SHORTWAVE, AND THE CMC
SLOWER/FLATTER. INTERESTINGLY, THE GFS WAS A PREFERRED
DETERMINISTIC SOLUTION FOR TONIGHT, WHICH WAS ALSO CLOSEST TO THE
FAIRLY AGREEABLE ENSEMBLE MEANS. BEHIND THIS TROUGH, THE MODELS
SUGGEST UPPER RIDGING SHOULD TRY TO BUILD BACK INTO THE WEST, BUT
WITH SOME UNCERTAINTIES ON POSSIBLE DISRUPTION FROM ANOTHER
SHORTWAVE.
THE WPC FORECAST UTILIZED A BLEND OF DETERMINISTIC GUIDANCE EARLY
IN THE FORECAST PERIOD, WITH A GRADUAL SHIFT TOWARD MORE GEFS AND
EC ENSEMBLE GUIDANCE WITH THE GFS BY LATE PERIOD GIVEN INCREASING
MODEL SPREAD. OVERALL, THIS APPROACH 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 INTO NEXT WEEKEND. ADDITIONAL ROUNDS OF RAIN
AND MOUNTAIN SNOWS COULD COME INTO CALIFORNIA THURSDAY-FRIDAY, BUT
MODELS VARY STILL 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 THERE ISN'T ENOUGH SUPPORT FOR EVEN A MARGINAL RISK
ON THE ERO AT THIS POINT STILL. PRECIPITATION LOOKS TO CLEAR OUT
OF MUCH OF THE INTERMOUNTAIN WEST BY SATURDAY, BUT MAY FOCUS AGAIN
IN THE PACIFIC NORTHWEST.
A LEADING SHORTWAVE AND SURFACE FRONT OUT OF THE WEST ON THURSDAY
SHOULD FOCUS MOISTURE AND SOME WEAK INSTABILITY TO FUEL RAIN AHEAD
OF THE COLD FRONT ACROSS THE MID-SOUTH. RAIN RATES AND AMOUNTS DO
NOT LOOK HIGH ENOUGH TO CAUSE FLOODING ISSUES GIVEN FAIRLY
PROGRESSIVE MOVEMENT. SHOWERS AND THUNDERSTORMS SHOULD THEN SETTLE
ACROSS THE GULF COAST/SOUTHEAST NEXT WEEKEND, MAINLY IN AREAS THAT
HAVE LOW ANTECEDENT SOIL MOISTURE LIMITING ANY FLOODING THREAT,
EXCEPT FARTHER WEST ACROSS LOUISIANA/ARKANSAS AND EASTERN TEXAS.
SOME INCREASING SUPPORT IN THE GUIDANCE FOR LOCALLY HEAVY
MULTI-DAY AMOUNTS FOR THIS REGION, BUT LOTS OF UNCERTAINTY AND
HIGHLY DEPENDENT ON EXACT EVOLUTION OF WESTERN U.S. TROUGHING.
THERE IS ALSO SOME SNOWFALL POTENTIAL ON THE NORTH SIDE OF THE
SURFACE CYCLONE ACROSS THE NORTH-CENTRAL U.S. INTO THURSDAY.
THE UPPER RIDGE INITIALLY FROM THE LOWER MISSISSIPPI VALLEY
THROUGH GREAT LAKES WILL SUPPORT A BROAD AREA OF UNSEASONABLY WARM
TEMPERATURES WHICH WILL SHIFT FROM THE UPPER MIDWEST/GREAT LAKES
THURSDAY-FRIDAY INTO THE NORTHEAST BY SATURDAY. DAYTIME HIGHS IN
THIS REGION COULD BE 20-30F ABOVE NORMAL, WITH POTENTIAL FOR
WIDESPREAD DAILY TEMPERATURE RECORDS. IN CONTRAST, THE SOUTHWEST
U.S./CALIFORNIA SHOULD SEE COOL BUT MODERATING WITH TIME DAYTIME
HIGHS THROUGH THE PERIOD WITH SOME AREAS AROUND 10-15F BELOW
NORMAL ON MULTIPLE DAYS. CLOUDS/PRECIPITATION OVER THE WEST SHOULD
KEEP MORNING LOWS NEAR TO ABOVE NORMAL THOUGH LATER THIS WEEK.
TEMPERATURES ACROSS THE ENTIRE EASTERN U.S. WILL TREND WARMER AS
THE PERIOD PROGRESSES, WHILE MODERATING A BIT CLOSER TO NORMAL IN
THE MIDWEST BY NEXT WEEKEND.
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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