663
FXUS02 KWBC 230724
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
223 AM EST FRI FEB 23 2024
VALID 12Z MON FEB 26 2024 - 12Z FRI MAR 01 2024
..OVERVIEW
AN UPPER RIDGE TRAVERSING THE CENTRAL AND EASTERN U.S. FOR THE
FIRST HALF OF NEXT WEEK WILL SPREAD MUCH ABOVE NORMAL TEMPERATURES
TO THE PLAINS AND MIDWEST AND THEN THE EAST. MEANWHILE NORTHERN
AND WEAKER SOUTHERN STREAM TROUGHING LOOKS TO TRACK INTO THE WEST
AND BRING COOLER TEMPERATURES, LOWER ELEVATION RAIN AND HIGHER
ELEVATION SNOW, AND WINDY CONDITIONS FROM THE WEST COAST TO THE
ROCKIES THROUGH EARLY NEXT WEEK. DOWNSTREAM TRANSLATION MAY THEN
SUPPORT EMERGING GENESIS OF SYSTEMS AND PRECIPITATION PATTERN FROM
THE SOUTH-CENTRAL U.S. TO THE MIDWEST/GREAT LAKES ONWARD INTO
MIDWEEK, ALONG WITH A POST-FRONTAL/TRAILING SOUTHWARD SURGE OF A
COLD CANADIAN HIGH PRESSURE AIRMASS TO OFFER SOME WINTRY
POTENTIAL, ALBEIT WITH MUCH UNCERTAINY AND LESS THAN STELLAR
CONTINUITY FOR THIS PERIOD AND ONWARD.
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIIDANCE REMAINS IN REASONABLY GOOD AGREEMENT THAT A NORTHERN
STREAM SYSTEM WILL CROSS SOUTHERN CANADA/NORTHERN TIER OF THE U.S.
TOWARDS THE NORTHEAST EARLY NEXT WEEK AS WEAK RIDGING IN THE
SOUTHERN STREAM PROCEEDS THE UPPER-LEVEL ENERGY TO THE WEST,
TRANSITIONING FROM NORTHWESTERN MEXICO/THE SOUTHWEST EASTWARD
ACROSS THE SOUTHERN PLAINS TOWARDS THE SOUTHEAST. INITIAL
SHORTWAVE ENERGY FOLLOWING THE RIDGE SHOULD BRING SUBSEQUENT
CYCLOGENESIS/SURFACE SYSTEM DEVELOPMENT OVER THE PLAINS, LIFTING
NORTHEASTWARD TOWARDS THE MIDWEST. THE GENERAL PATTERN SHIFTS
TOWARDS MEAN TROUGHING IN THE WEST EARLY NEXT WEEK AS THE UPSTREAM
ENERGIES APPROACH.
THE MAIN FORECAST CHALLENGE FOR NEXT WEEK REMAINS WITH HOW A
STRONG NORTHERN STREAM TROUGH DROPPING SOUTH UPSTREAM FROM THE
NORTHEASTERN PACIFIC AND CLOSED UPPER-LOW IN THE SOUTHERN STREAM
OFF THE COAST OF CALIFORNIA PROGRESS AND EVOLVE TOGETHER ACROSS
THE CONUS THROUGH NEXT WEEK. DETERMINISTIC MODELS AND ENSEMBLES
OVER THE PAST FEW DAYS HAVE FAVORED STREAM UPPER TROUGH PHASING
OVER THE WEST EARLY NEXT WEEK WITH A NORTHERN STREAM TROUGH DROPS
ACROSS THE PACIFIC NORTHWEST AND THE SOUTHERN STREAM CLOSED LOW
BREAKING DOWN AS ENERGY EJECTS EASTWARD OVER THE
SOUTHWEST/CALIFORNIA/BAJA. MACHINE LEARNING SYSTEMS MOSTLY DID NOT
FAVOR SIGNIFICANT PHASING OF THESE SYSTEM WITH MORE INDEPENDENT
DOWNSTREAM PROGRESSION OF POTENT NORTHERN STREAM ENERGIES. THIS
SEEMS TO MAKE MORE SENSE AS THE STRONG UPPER JET FLOW OVER THE
PACIFIC INTRODUCES VERY UNCERTAIN PHASING TIMING ISSUES, AS WELL
AS THE HISTORIC TENDANCY FOR CLOSED SOUTHERN STREAM SYSTEMS TO
LINGER IN SEPARATED FLOW. 12 UTC GUIDANCE STARTED TO SHOW A DENT
IN MODEL/ENSEMBLE THINKING, BUT WITH ONLY THE 12 UTC ECMWF/ECMWF
ENSEMBLES MAKING A CHANGE AWAY FROM PHASING. GIVEN THE
AFOREMENTIONED THOUGHT PROCESS THOUGH, THE WPC PRODUCT SUITE HAS
NOW EMBRACED A SOLUTION WITH MUCH LESS PHASING NEXT WEEK AND
SHIFTED CONTINUITY CLOSER TO THE ECMWF ENSEMBLE MEAN GIVEN
LINGERING UNCERTAINTIES. WHILE EITHER FORECAST CAMP REMAINS
PLAUSIBLE, UPDATED INFORMATION FROM THE LATEST 00 UTC GUIDANCE
CYCLE DOES NOW ALSO HAVE THE UKMET JOINING THE ECMWF/ECMWF
ENSEMBLE BASED SOLUTION.
..WEATHER/HAZARDS HIGHLIGHTS
AS TROUGHING COMES INTO THE WEST EARLY NEXT WEEK, PRECIPITATION
WILL SPREAD INTO THE PACIFIC NORTHWEST AND NORTHERN ROCKIES INTO
MONDAY, INCLUDING SNOW THAT COULD BE HEAVY OVER FAVORED TERRAIN.
PRECIPITATION MAY NOW SPREAD THROUGH CALIFORNIA AND INTO THE
INTERMOUNTAIN WEST BY MONDAY, THEN OUT THROUGH THE ROCKIES TUESDAY
GIVEN LESS LIKELY STREAM PHASING AND NORTHERN STREAM UPPER TROUGH
PROGRESSION. ADDITIONAL MOISTURE AHEAD OF ADDITIONAL SYSTEMS
UPSTREAM OVER THE PACIFIC WILL CONTINUE PRECIPITATION CHANCES IN
THE PACIFIC NORTHWEST THEN CALIFORNIA THROUGH WEDNESDAY-NEXT
FRIDAY. OVERALL, THE HIGHEST LIKELIHOOD FOR WINTER-RELATED IMPACTS
IS IN THE CASCADES, SIERRA, AND PORTIONS OF THE NORTHERN/CENTRAL
ROCKIES, THOUGH MOST OF THE REGIONAL HIGHER ELEVATION MOUNTAIN
RANGES WILL AT LEAST SEE SOME SNOW THROUGH THE PERIOD. WIDESPREAD
STRONG, GUSTY WINDS ARE ALSO EXPECTED ACROSS MUCH OF THE WEST,
PARTICULARLY FOR HIGHER ELEVATIONS, AS A COUPLE FRONTAL SYSTEMS
PASS THROUGH, LINGERING THE LONGEST ALONG THE EASTERN
RANGES/FOOTHILLS OF THE ROCKIES AND IMMEDIATE HIGH PLAINS.
PRECIPITATION CHANCES WILL BEGIN TO INCREASE TUESDAY INTO
WEDNESDAY ACROSS MUCH OF THE EASTERN HALF TO THIRD OF THE COUNTRY
AS MOIST SOUTHERLY FLOW INCREASES AHEAD OF THE APPROACHING
UPPER-LEVEL TROUGH AND SURFACE LOW PRESSURE/FRONTAL SYSTEM FROM
THE WEST. MOST PRECIPITATION WILL BE IN THE FORM OF RAIN GIVEN
ANOMALOUS LEAD WARMTH, BUT SOME SNOW ON THE BACKSIDE OF THE LOW
AND COLD FRONT FOR THE UPPER MIDWEST/GREAT LAKES. THE WPC WINTER
WEATHER OUTLOOK HAS INCREASED PROBABILITIES THERE GIVEN THE LOW
AND POST-FRONTAL COLD ONSET. SOME RAINFALL AMOUNTS COULD BE
MODERATELY HEAVY, PARTICULARLY FOR THE OHIO VALLEY, WITH MULTIPLE
ROUNDS OF RAIN POSSIBLE THROUGH AT LEAST MIDWEEK. IN ADDITION, THE
MOIST, UNSTABLE AIRMASS AS WELL AS INCREASINGLY STRONG WINDS ALOFT
WITH THE APPROACHING TROUGH WILL BRING THE CHANCE FOR SOME SEVERE
THUNDERSTORMS, WITH THE STORM PREDICTION CENTER HIGHLIGHTING THIS
THREAT FROM THE SOUTHERN PLAINS TO MIDDLE MISSISSIPPI VALLEY
TUESDAY AND INTO THE MID-SOUTH AND OHIO/TENNESSEE VALLEYS
WEDNESDAY. LATER WEEK PRECIPITATION FOCUS MAY SPREAD OVER THE
EAST, THEN RETURN/LINGER OVER THE SOUTH, BUT GUIDANCE IS MURKY ON
THE SCENARIO TO BE MONITORED CLOSER TO THE EVENT.
THE CENTRAL U.S. WILL SEE QUITE MILD TO WARM TEMPERATURES EARLY
NEXT WEEK UNDERNEATH AN UPPER RIDGE. TEMPERATURES OF 20-35 DEGREES
ABOVE AVERAGE WILL EXPAND THROUGHOUT THE PLAINS AND MISSISSIPPI
VALLEY, PUTTING ACTUAL TEMPERATURES INTO THE 80S AND EVEN 90S IN
TEXAS BY MONDAY-TUESDAY WHILE 60S REACH AS FAR NORTH AS SOUTH
DAKOTA AND IOWA, WITH POTENTIAL FOR WIDESPREAD RECORDS. THE UPPER
TROUGH AND COLD FRONT PRESSING EASTWARD SHOULD COOL TEMPERATURES
DOWN CLOSER TO NORMAL OR A FEW DEGREES BELOW IN THE CENTRAL U.S.
BY MIDWEEK, BUT TEMPERATURES COULD ALREADY START TO REBOUND BY
THURSDAY. THE WELL ABOVE NORMAL TO POSSIBLY RECORD-BREAKING
TEMPERATURES WILL GET SHUNTED EASTWARD AHEAD OF THE UPPER
TROUGH/UNDERNEATH THE UPPER RIDGE INTO THE EAST-CENTRAL AND THEN
EASTERN U.S. TUESDAY-THURSDAY. 70S SHOULD BE WIDESPREAD ACROSS THE
SOUTHEAST AND COULD EVEN REACH AS FAR NORTH AS THE MID-ATLANTIC.
MEANWHILE THE WEST IS FORECAST TO SEE NEAR TO SLIGHTLY ABOVE
NORMAL TEMPERATURES INTO SUNDAY, BUT COOLING TO BELOW NORMAL
PARTICULARLY IN TERMS OF HIGHS BY MONDAY-TUESDAY AS UPPER
TROUGHING COMES IN.
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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