669
FXUS02 KWBC 050717
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
217 AM EST SUN FEB 05 2023
VALID 12Z WED FEB 08 2023 - 12Z SUN FEB 12 2023
..GUIDANCE/PREDICTABILITY ASSESSMENT
LATEST MODEL AND ENSEMBLE SOLUTIONS NOW SEEM BETTER CLUSTERED
VALID WEDNESDAY-THURSDAY, BOLSTERING FORECAST CONFIDENCE COMPARED
TO LESS THAN STELLAR RUNS OVER THE PAST FEW DAYS. PREFER A
COMPOSITE OF THE GFS/ECMWF/UKMET/CANADIAN TO MITIGATE CONSISTENT
WITH UNCERTAINTY AMPLE LINGERING SMALLER SCALE SYSTEM DIFFERENCES.
THE GFS/ECMWF SOLUTIONS SEEMS TO CLUSTER BEST WITH ENSEMBLES
HEADING INTO/THROUGH NEXT WEEKEND AND A COMPOSITE SEEMS TO OFFER A
REASONABLE FORECAST BASIS AMID GROWING FORECAST SPREAD IN HIGHLY
AMPLIFYING/SLOWING FLOW WITH LIKELY DEVELOPMENT OF STRONG UPPER
TROUGHS OVER THE EAST-CENTRAL U.S. AND OFF THE WEST COAST ALONG
WITH AMPLE UPPER RIDGES OVER THE WEST-CENTRAL U.S. AND WESTERN
ATLANTIC. THERE REMAINS SOME STREAM PHASING UNCERTAINTIES AS A
MORE PROGRESSIVE NORTHERN STREAM PERIODICALLY DIGS SHORTWAVE
ENERGY/COLD AIR DEEPER SOUTHWARD INTO THE LOWER 48.
..WEATHER/HAZARD HIGHLIGHTS
AN INITIALLY CLOSED SOUTHERN STREAM UPPER TROUGH/LOW WILL EJECT
INTO THE SOUTHERN PLAINS BY MIDWEEK AS A KICKER SHORTWAVE TROUGH
DIGS SOUTHEASTWARD THROUGH THE GREAT BASIN TO SUPPORT SOME
POTENTIAL FOR SNOW THERE INTO THE ROCKIES. DOWNSTREAM, A SURFACE
FRONTAL WAVE OVER TEXAS WITH THE LEAD SYSTEM WILL ORGANIZE, DEEPEN
AND OCCLUDE WHILE LIFTING NORTHEAST INTO THE MIDWEST/OH VALLEY
THURSDAY BEFORE EXITING THROUGH THE NORTHEAST FRIDAY. GULF
MOISTURE INFLOW/INSTABILITY AND SUPPORTIVE UPPER JET/HEIGHT FALLS
WILL COMBINE WITH THE ASSOCIATED FRONTAL SYSTEM TO PRODUCE A SWATH
OF HEAVY RAIN/CONVECTION THIS PERIOD ACROSS THE LOWER/MID MS AND
TN/OH VALLEYS, WITH WIDESPREAD MODERATE RAINS THEN SHEARING ACROSS
THE APPALACHIANS AND EASTERN SEABOARD. THE WPC EXPERIMENTAL DAY 4
EXCESSIVE RAINFALL OUTLOOK (ERO) WILL SHOW A "MARGINAL" THREAT
AREA OVER THE MID-LOWER MS VALLEY AND VICINITY THROUGH WEDENSDAY,
EXTENDING FROM A DAY 3 MARGINAL AND SLIGHT RISK AREA JUST
UPSTREAM. 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 HEAVY SNOW/ICE ON THE NORTHERN PERIPHERY
OF THE EXPANDING PRECIPITATION SHIELD THIS PERIOD 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.
UPSTREAM, THERE IS A GROWING GUIDANCE SIGNAL FOR THE AMPLIFICATION
OF THE OVERALL FLOW SIGNIFICANTLY INTO LATER WEEK ACROSS THE
NATION AND ADJOINING OCEANS, BUT WITH LIMITED PRECIPITATION
RE-EMERGENCE OVERALL AT THIS POINT. ORGANIZED RAINS STAY MAINLY
OFF THE WEST COAST THIS PERIOD, WITH SIGNIFICANT EASTERN PACIFIC
STORM DEVELOPMENT HELD JUST OFFSHORE. RENEWED SHORTWAVE APPROACH
OUT FROM THE WEST AND POTENTIALLY THE NORTHERN STREAM WILL
MEANWHILE HELP CARVE OUT AN AMPLIFIED CENTRAL TO EAST-CENTRAL
UPPER TROUGH POSITION LATER WEEK INTO NEXT WEEKEND, BUT RESPONDING
SURFACE SYSTEM DEVELOPMENT DOES NOT SEEM TO HAVE DEEP MOISTURE
INFLOW IN THE WAKE OF THE AFOREMENTIONED LEAD MAIN SYSTEM, SO
EXPECT AN EXPANDING AREA OF OVERALL MODERATE RAINFALL SIGNATURE
WITH A MAIN FOCUS LIKELY TO LIFT FROM THE SOUTHEAST TO UP THE EAST
COAST NEXT WEEKEND WITH MODEST COASTAL LOW GENESIS AND ATLANTIC
INFLOW THAT COULD OFFER A LATE PERIOD INTERIOR SNOW THREAT OVER
THE NORTHEAST TO MONITOR.
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, 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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