202
FXUS02 KWBC 031858
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
158 PM EST SAT FEB 03 2024
VALID 12Z TUE FEB 06 2024 - 12Z SAT FEB 10 2024
...ATMOSPHERIC RIVER WINDING DOWN OVER CALIFORNIA BY TUESDAY WITH
MOISTURE ALSO SPREADING INLAND ACROSS THE WEST...
..OVERVIEW
AN ACTIVE WEATHER PATTERN WILL BE IN PLACE ACROSS THE WEST AS THE
PERIOD BEGINS TUESDAY WITH A LARGE SCALE POSITIVELY TILTED MEAN
TROUGH CONTINUING TO PROMOTE A STRONG SOUTHWESTERLY FLOW OF
MOISTURE INTO THE WEST THROUGH ABOUT MIDWEEK. SIGNIFICANT RAIN AND
MOUNTAIN SNOWS EXPECTED ACROSS CALIFORNIA EARLIER IN THE WEEK
SHOULD BE WANING BY TUESDAY, BUT THERE SHOULD BE SOME LINGERING
HEAVY RAINFALL AT LEAST LOCALLY ACROSS SOUTHERN CALIFORNIA WITH
MOISTURE ALSO EXTENDING INTO PARTS OF THE INTERMOUNTAIN WEST AND
ROCKIES. MEANWHILE A STRONG UPPER RIDGE ACROSS THE CENTRAL U.S.
WILL CONTINUE TO SUPPORT WELL ABOVE NORMAL TEMPERATURES THAT COULD
BE RECORD-SETTING ACROSS THE CENTRAL/NORTHERN PLAINS AND MIDWEST.
LATER IN THE WEEK, ENERGY FROM THE MEAN UPPER TROUGH OVER THE WEST
WILL EJECT INTO THE CENTRAL U.S., PUSHING THE RIDGE AND WARM
TEMPERATURES SLOWLY EASTWARD.
..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 WITH SENSIBLE WEATHER IMPACTS. THESE
DIFFERENCES MAINLY FOCUS OUT WEST AS MULTIPLE PIECES OF ENERGY DIG
DOWN THE WESTERN SIDE AND MERGE WITH THE MAIN TROUGH. THE
GFS/ECMWF GUIDANCE SEEMS TO BE CONVERGING SOMEWHAT ON SHOWING A
SHORTWAVE OR WEAK CLOSED LOW COMING INTO THE NORTHWEST
WEDNESDAY-THURSDAY, WHILE THE 00Z CMC WAS A STRONGER AND FARTHER
SOUTHWEST OUTLIER COMPARATIVELY WITH THE CLOSED LOW. THE 12Z CMC
APPEARS SOMEWHAT MORE IN LINE WITH THE OTHER GUIDANCE, BUT
CONFIDENCE IS STILL NOT HIGH GIVEN THE ENERGY'S ORIGINS FROM THE
TYPICALLY UNCERTAIN NORTHERN PACIFIC. MODEL DIFFERENCES PERSIST AS
SOME SHORTWAVE ENERGY TRACKS INTO THE NORTH-CENTRAL U.S. WHILE
SOME LINGERS/IS REINFORCED IN THE NORTHWEST. A SURFACE LOW
ASSOCIATED WITH THE NORTH-CENTRAL U.S. ENERGY SHOWS SOME FAIRLY
TYPICAL SPREAD FOR THE DAYS 5-7 PERIOD BUT FORTUNATELY WITH SOME
MODEL CONVERGENCE IN THE 12Z GUIDANCE.
THE WPC FORECAST FOR TONIGHT WAS ABLE TO UTILIZE A DETERMINISTIC
MODEL BLEND FOR THE FIRST COUPLE OF DAYS, WITH THE BLENDING
PROCESS INITIALLY SUFFICIENT TO HANDLE THE GROWING UNCERTAINTY OUT
WEST. THOUGH BY THURSDAY, INCREASING AMOUNTS OF THE AGREEABLE
ENSEMBLE MEANS WERE INCORPORATED TO ATTEMPT TO SMOOTH OUT THE
DIFFERENCES, REACHING HALF THE BLEND BY DAY 6 AND JUST OVER HALF
BY DAY 7. THIS MAINTAINED GOOD CONTINUITY WITH THE PREVIOUS WPC
FORECAST AS WELL.
..WEATHER/HAZARDS HIGHLIGHTS
THE SLOW MOVEMENT OF THE WESTERN U.S. UPPER TROUGH SHOULD PRODUCE
A CONTINUED SOUTHWESTERLY FLOW OF MOISTURE INTO SOUTHERN
CALIFORNIA THROUGH EARLY TUESDAY WHILE THE LEADING EDGE OF THE
MOISTURE SHOULD PUSH INTO THE SOUTHWEST/GREAT BASIN. THE DAY
4/TUESDAY ERO SHOWS A BROAD MARGINAL RISK AREA FROM SOUTHERN
CALIFORNIA INTO THE SOUTHWEST, WITH SMALLER SLIGHT RISKS
HIGHLIGHTED FOR THE LA-SAN DIEGO CORRIDOR AS WELL AS ACROSS PARTS
OF WEST-CENTRAL ARIZONA. CONTINUED A MARGINAL RISK ACROSS PARTS OF
ARIZONA INTO WEDNESDAY AS MOISTURE MAY LINGER INTO THE EARLY PART
OF THE PERIOD, BEFORE THE BETTER INSTABILITY AND MOISTURE PUSHES
EAST. HEAVY SNOW IN THE HIGHER TERRAIN ACROSS MUCH OF THE WEST IS
EXPECTED IN THIS OVERALL PATTERN AS WELL, WITH POSSIBLY
SIGNIFICANT MULTI-DAY TOTALS OF MULTIPLE FEET OF SNOW FOR PARTS OF
THE SIERRA NEVADA, WITH THE LARGEST SNOW AMOUNTS NOW IN THE SHORT
RANGE. ADDITIONAL ROUNDS OF PRECIPITATION ARE POSSIBLE ACROSS THE
WEST FOR THE LATTER HALF OF THE WEEK, BUT MUCH LIGHTER THAN WHAT
IS EXPECTED EARLY IN THE WEEK.
AS LEADING ENERGY FROM THE WESTERN TROUGH EJECTS INTO THE PLAINS,
THIS SHOULD HELP SPIN UP A MODERATELY DEEP SURFACE CYCLONE THAT
TRACKS NORTHEASTWARD WITH TIME INTO THE UPPER MIDWEST LATE WEEK.
THE ASSOCIATED COLD FRONT SHOULD HELP PULL MOISTURE NORTHWARD TO
FUEL PRECIPITATION, WITH POSSIBLE SNOW IN THE NORTH-CENTRAL U.S.,
THOUGH WITH STILL PLENTY OF UNCERTAINTY IN THE EXACT AMOUNTS AND
PLACEMENT.
THE UPPER RIDGE FROM THE SOUTHERN PLAINS THROUGH GREAT LAKES WILL
SUPPORT A BROAD AREA OF UNSEASONABLY WARM TEMPERATURES OVER THE
CENTRAL U.S. AND MIDWEST THROUGH MUCH OF THE WEEK. CONTINUE TO
EXPECT THE GREATEST ANOMALIES TO BE OVER/NEAR THE UPPER MIDWEST
WHERE MORNING LOWS AND DAYTIME HIGHS MAY BE AS WARM AS 25-35F
ABOVE NORMAL THROUGH AT LEAST THURSDAY WITH INCREASING POTENTIAL
FOR WIDESPREAD DAILY TEMPERATURE RECORDS. IN CONTRAST, THE
SOUTHWEST U.S./CALIFORNIA SHOULD SEE COOL 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 UNTIL LATER NEXT WEEK. FLORIDA SHOULD SEE A
COUPLE COOL DAYS WITH HIGHS 5-10F BELOW NORMAL TUESDAY-WEDNESDAY.
TEMPERATURES ACROSS THE EAST SHOULD TREND WARMER AS THE WEEK
PROGRESSES WITH THE UPPER RIDGE BUILDING IN, AND DAYTIME HIGHS BY
FRIDAY-SATURDAY COULD BE APPROACHING 10-20 DEGREES ABOVE NORMAL
FOR SOME LOCATIONS, WHILE MODERATING A BIT CLOSER TO NORMAL IN THE
MIDWEST.
TATE/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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