394
FXUS02 KWBC 041854
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
154 PM EST SUN FEB 04 2024
VALID 12Z WED FEB 07 2024 - 12Z SUN FEB 11 2024
..OVERVIEW
BROAD AND RENEWED TROUGHING OVER THE WEST INTO NEXT WEEKEND 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 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. SHORTWAVES/ENERGY FROM THE
MEAN UPPER TROUGH OVER THE WEST WILL PERIODICALLY EJECT INTO THE
CENTRAL U.S., PUSHING THE RIDGE AND WARM TEMPERATURES SLOWLY
EASTWARD WITH TIME.
..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 AS MULTIPLE PIECES OF
ENERGY DIG DOWN THE WESTERN SIDE AND MERGE WITH THE MAIN TROUGH.
THE 00Z ECMWF WAS A BIT ODD WITH ITS TREATMENT OF A NARROW CLOSED
LOW DROPPING MORE SOUTHWEST THAN OTHER GUIDANCE EVEN BY
WEDNESDAY-THURSDAY, BUT THE 12Z ECMWF SEEMS TO SHOW BETTER
ALIGNMENT. FARTHER EAST, OVERALL THERE IS INCREASING MODEL
CONSENSUS WITH THE LEADING ENERGY EJECTING INTO THE UPPER MIDWEST
MID-LATE WEEK, AND THE RESULTANT SURFACE LOW SHOWS BETTER
AGREEMENT IN DEPTH AND POSITION COMPARED TO A DAY AGO.
MULTIPLE SHORTWAVES LATE WEEK INTO THE WEEKEND MOVING INTO/TOWARD
THE TROUGH HAVE LOW PREDICTABILITY. INITIALLY THE GFS SEEMED TO BE
ON ITS OWN IN PULLING ROBUST ENERGY SOUTHWARD ATOP CALIFORNIA, BUT
OTHER GUIDANCE HAS TRENDED TOWARDS THIS STRONGER SOLUTION TO SOME
EXTENT. THE DETAILS REMAIN LOW CONFIDENCE THOUGH. THERE MAY BE A
PERIOD OF RIDGING BY EARLY NEXT WEEK ACROSS THE WEST COAST ON THE
LARGE SCALE AS THE TROUGH AXIS SHIFTS INTO THE INTERMOUNTAIN
WEST/HIGH PLAINS, BUT THIS RIDGE COULD BE DISRUPTED BY ANOTHER
POTENT 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 BY LATE PERIOD GIVEN INCREASING MODEL SPREAD.
OVERALL, THIS APPROACH MAINTAINED GOOD CONTINUITY WITH THE
PREVIOUS WPC FORECAST. ONE CHANGE WAS TO PRESS THE FRONT FARTHER
SOUTH ACROSS THE SOUTHEAST BY DAYS 6-7 PER RECENT MODEL GUIDANCE.
..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 MUCH OF THE PERIOD. ON DAY
4/WEDNESDAY, CONTINUED TO HIGHLIGHT A MARGINAL RISK ON THE
EXCESSIVE RAINFALL OUTLOOK ACROSS PARTS OF SOUTHERN ARIZONA WHERE
THE BETTER MOISTURE AND INSTABILITY SHOULD BE LOCATED. ADDITIONAL
ROUNDS OF RAIN AND MOUNTAIN SNOWS COULD COME INTO CALIFORNIA
WEDNESDAY-FRIDAY. BUT MODELS VARY MORE THAN USUAL WITH THE AMOUNTS
AND POSITION OF HEAVIEST PRECIPITATION. IN FACT, THE MOST RECENT
MODEL GUIDANCE HAS A MINIMUM OF PRECIPITATION ALONG CENTRAL AND
NORTHERN PARTS OF THE CALIFORNIA COAST WHERE THE PREVIOUSLY ISSUED
MARGINAL RISK WAS. SOME FLASH FLOODING RISK IS POSSIBLE SOMEWHERE
AND SOMETIME, ESPECIALLY IF ADDITIONAL PRECIPITATION FALLS OVER
SOUTHERN CALIFORNIA THAT WILL BE QUITE SENSITIVE, BUT WILL HAVE TO
LEAVE THIS TO FUTURE UPDATES IF MODEL GUIDANCE CONVERGES. PULLED
THE MARGINAL RISK FOR NOW DUE TO LACK OF RAINFALL AND AGREEMENT.
HIGHER ELEVATION SNOW AND LOWER ELEVATION RAIN CONTINUE INTO THE
INTERMOUNTAIN WEST THROUGH THE LATTER PART OF THE WEEK. FINALLY
PRECIPITATION LOOKS TO CLEAR OUT OF MUCH OF CALIFORNIA AND NEVADA
BY SATURDAY, BUT COULD FOCUS IN THE PACIFIC NORTHWEST.
AS LEADING ENERGY EJECTS OUT OF THE WESTERN TROUGH INTO THE
CENTRAL U.S. BY THURSDAY, MOISTURE AND SOME WEAK INSTABILITY
SHOULD HELP 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. THERE IS SOME SNOWFALL
POTENTIAL ON THE NORTH SIDE OF THE SURFACE CYCLONE ACROSS THE
NORTH-CENTRAL U.S. WEDNESDAY-THURSDAY, BUT SOME UNCERTAINTY STILL
ON EXACT AMOUNTS.
THE UPPER RIDGE INITIALLY FROM THE LOWER MISSISSIPPI VALLEY
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/GREAT LAKES WHERE MORNING LOWS AND DAYTIME HIGHS
MAY BE AS WARM AS 25-35F ABOVE NORMAL THROUGH AT LEAST FRIDAY 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 THIS WEEK.
TEMPERATURES ACROSS THE EAST SHOULD TREND WARMER 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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