772
FXUS02 KWBC 062043
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
341 PM EST MON FEB 06 2023
VALID 12Z THU FEB 09 2023 - 12Z MON FEB 13 2023
..OVERVIEW
A FAIRLY WAVY AND PROGRESSIVE PATTERN WILL REMAIN IN PLACE THROUGH
EARLY NEXT WEEK. FOR THE LATTER PART OF THIS WEEK UPPER TROUGHING
WILL PROGRESS ACROSS THE CENTRAL TO EASTERN U.S., WITH A COUPLE OF
SURFACE LOW PRESSURE SYSTEMS PRODUCING SNOW ACROSS THE
NORTH-CENTRAL U.S. AND PERHAPS THE NORTHEAST, WHILE HEAVY RAIN IS
A POSSIBILITY IN THE SOUTHEAST. AS AN UPSTREAM UPPER RIDGE
TRAVERSES ACROSS THE LOWER 48 BEHIND THE FIRST TROUGH, ANOTHER
TROUGH/POTENTIAL UPPER LOW LOOKS TO COME INTO THE WEST THIS
WEEKEND/EARLY NEXT WEEK WITH SOME TIMING UNCERTAINTY. WEATHER-WISE
THIS COULD PRODUCE SCATTERED PRECIPITATION ACROSS THE WEST,
ESPECIALLY THE PACIFIC NORTHWEST, AND THEN RAIN CHANCES ARE
EXPECTED TO RISE IN THE SOUTH-CENTRAL U.S. EARLY NEXT WEEK AS GULF
MOISTURE STREAMS IN AHEAD OF THE TROUGH/LOW.
..GUIDANCE/PREDICTABILITY ASSESSMENT
AS THE MEDIUM RANGE PERIOD BEGINS THURSDAY, RECENT MODEL GUIDANCE
IS IN GOOD AGREEMENT REGARDING CENTRAL U.S. TROUGHING, THOUGH
EXACT SHORTWAVE PLACEMENT REMAINS A BIT IN QUESTION, WHILE THE
POSITION OF A SURFACE LOW OVER THE OHIO VALLEY AND THE TRAILING
COLD FRONT ARE REASONABLY AGREEABLE. BUT BY LATER DAY 4/FRIDAY AND
BEYOND, MODELS DIVERGE WITH THE TIMING OF THE TROUGH FARTHER WEST
OVER THE PACIFIC/CALIFORNIA AND ITS INTERFACE WITH THE RIDGE TO
ITS EAST. OVER THE PAST 24 HOURS OR SO, SOME MODELS HAVE TRENDED
TOWARD A MORE PHASED AND PROGRESSIVE PATTERN WITH THE TROUGH
FRIDAY AND INTO THE WEEKEND, AS OPPOSED TO A SOUTHERN STREAM UPPER
LOW CLOSING OFF OVER THE PACIFIC LIKE EARLIER MODELS GENERALLY
AGREED UPON. NAMELY, THE GFS RUNS AND THE 00Z ECMWF TRANSITIONED
TO A MORE PHASED AND PROGRESSIVE PATTERN, WHICH ALSO SERVED TO
SUPPRESS THE RIDGE ON ITS WESTERN SIDE SOMEWHAT, THOUGH THOUGHT
THE 00Z GFS MAY HAVE BEEN TOO SUPPRESSED WITH THE RIDGE ESPECIALLY
COMPARED TO ENSEMBLE MEMBERS AND PREFERRED THE 06Z INSTEAD. THE
ENSEMBLE MEANS GENERALLY FOLLOWED THEIR RESPECTIVE DETERMINISTIC
MODELS WITH A PROGRESSIVE TREND OF THE SOUTHERN STREAM TROUGH/LOW.
OVERALL IT SEEMED PRUDENT TO LEAN TOWARD A FASTER PROGRESSION OF
THE TROUGH/LOW AND THE ASSOCIATED FRONTAL SYSTEM INLAND COMPARED
TO ITS PREVIOUS FORECAST, WHICH THE WPC FORECAST DID BY LEANING
TOWARD THE ECENS MEAN AS WELL AS SOME DETERMINISTIC GFS AND ECMWF.
THE EC MEAN WAS CONSIDERED A REASONABLE MIDDLE GROUND WITH AN
INLAND TREND BUT NOT QUITE AS FAST AS THE DETERMINISTIC MODELS.
HOWEVER, THE 00Z CMC AND UKMET KEPT WITH A CLOSED LOW, ADDING TO
THE UNCERTAINTY FOR THIS TREND. IN THE NEWER 12Z GUIDANCE CYCLE,
THE CMC TRENDED FASTER, THE GFS REMAINED FAST, THE UKMET REMAINED
SLOW, AND THE ECMWF ACTUALLY SWITCHED TO BE SLOWER, CLOSING OFF AN
UPPER LOW IN THE PACIFIC. OVERALL THIS IS FAR FROM RESOLVED, SO
EXPECT POTENTIAL FOR FUTURE CHANGES IN UPDATED FORECASTS. BY LATER
SUNDAY INTO MONDAY, MODELS DO EXPECT A CLOSED LOW TO HAVE FORMED
BY THEN, ADMITTEDLY WITH SOME DIFFERENCES IN POSITION.
..WEATHER/HAZARD HIGHLIGHTS
AN INITIALLY POTENT SOUTHERN STREAM UPPER TROUGH WILL EJECT
NORTHEASTWARD FROM THE MS VALLEY THROUGH THE NORTHEAST
THURSDAY/FRIDAY AS A KICKER UPPER TROUGH DIGS SOUTHEASTWARD
THROUGH THE ROCKIES TO THE SOUTH-CENTRAL U.S., AMPLIFYING
DOWNSTREAM OF A BUILDING UPPER RIDGE OVER THE WEST. IN THIS
PATTERN, A LEAD SURFACE LOW WILL DEEPEN AND TRACK ACROSS THE
MIDWEST/OH VALLEY THURSDAY BEFORE EXITING THROUGH THE NORTHEAST
FRIDAY. GULF MOISTURE INFLOW/INSTABILITY AND RIGHT ENTRANCE REGION
UPPER JET/HEIGHT FALLS SUPPORT WILL COMBINE WITH THE ASSOCIATED
FRONTAL SYSTEM TO PRODUCE A WIDESPREAD SWATH OF RAINFALL ACROSS
THE APPALACHIANS AND EASTERN SEABOARD. HEAVIEST POTENTIAL AND SOME
RISK OF RUNOFF ISSUES WITH REPEAT/TRAINING OF CELLS TO MONITOR IN
THE COMING DAYS MAY BE ALONG A TRAILING COLD FRONT TO SLOW OVER
THE MOIST SOILS OF THE SOUTHEAST AS THE UPSTREAM UPPER TROUGH IS
CARVED OUT OVER THE SOUTH-CENTRAL U.S. AND SUBSEQUENTLY WORKS
SLOWLY EASTWARD. RAIN RATES COULD BE HIGH GIVEN THE POTENTIAL FOR
INSTABILITY TO BE IN PLACE. MEANWHILE, COLD AIR DRAPED TO THE
NORTH OF THE SYSTEM AND SEVERAL POTENT SHOTS OF CANADIAN AIR IN
THE WAKE OF SYSTEM PASSAGE WILL ALSO OFFER A THREAT FOR WRAPBACK
AND LEAD FLOW SNOW/ICE ON THE NORTHERN PERIPHERY OF THE EXPANDING
PRECIPITATION SHIELD OUT FROM THE CENTRAL PLAINS THROUGH THE GREAT
LAKES AND INTERIOR NORTHEAST AND SOUTHERN CANADA. EXPECT
LAKE-EFFECT SNOWS INTO THE WEEKEND GIVEN LINGERING COLD/WINDY
FLOW. UPPER TROUGH ENERGY SLATED TO LIFT FROM THE SOUTHEAST TO UP
THE EAST COAST FOR THE WEEKEND AND MODEST COASTAL LOW GENESIS AND
ATLANTIC INFLOW COULD RENEW A MAINLY INTERIOR NORTHEAST SNOW
THREAT TO MONITOR FOR SATURDAY. COLD FRONTS PASSING AHEAD OF THE
TROUGH IN THE EAST SHOULD LEAD TO A TRANSITION FROM ABOVE NORMAL
TEMPERATURES THROUGH LATE WORKWEEK TO NEAR NORMAL CONDITIONS FOR
THE WEEKEND.
WHILE THERE IS A GROWING GUIDANCE SIGNAL FOR THE AMPLIFICATION OF
THE OVERALL FLOW SIGNIFICANTLY BY LATER WEEK ACROSS THE NATION AND
ADJOINING OCEANS, SUBSEQUENT PRECIPITATION RE-EMERGENCE MAY
OTHERWISE BE LIMITED THROUGH THE WEEKEND. NORTHERN STREAM
SHORTWAVE TROUGH PASSAGE SHOULD SUPPORT MODEST PRECIPITATION SHOTS
REPEATEDLY OVER MAINLY THE PACIFIC NORTHWEST. UNCERTAIN EASTERN
PACIFIC/WEST COAST UPPER TROUGH/LOW AMPLIFICATION COULD LEAD TO
MODEST PRECIPITATION ACROSS THE WEST BUT WITH UNCERTAINTY AS TO
WHERE THIS COULD OCCUR, DEPENDENT ON HOW THE UPPER TROUGH/LOW AXIS
ENDS UP DEVELOPING. BUT WITH GUIDANCE POINTING TOWARD AN UPPER LOW
IN THE SOUTHWEST BY AROUND MONDAY, GULF MOISTURE STREAMING AHEAD
OF IT COULD RENEW A RAINFALL THREAT IN THE SOUTHERN PLAINS TO
LOWER MS VALLEY BY MONDAY-TUESDAY.
TATE/SCHICHTEL
HAZARDS:
- HEAVY PRECIPITATION ACROSS PORTIONS OF NORTHERN NEW ENGLAND,
THU-FRI, FEB 9-FEB 10, AND SAT, FEB 11.
- HEAVY RAIN ACROSS PORTIONS OF THE FLORIDA PANHANDLE TO THE
MID-ATLANTIC, THU-FRI, FEB 9-FEB 10.
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTHERN PLAINS TO THE
MID-MISSISSIPPI VALLEY, MON, FEB 13.
- HEAVY SNOW ACROSS PORTIONS OF THE UPPER MIDWEST TO THE UPPER
GREAT LAKES, THU, FEB 9.
- HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN CASCADES, MON, FEB 13.
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE LOWER
MISSISSIPPI VALLEY.
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE ALASKA PANHANDLE,
THU, FEB 9.
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, EXPERIMENTAL EXCESSIVE RAINFALL
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES AND HEAT INDICES 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
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