448
FXUS02 KWBC 200700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 AM EST FRI JAN 20 2023
VALID 12Z MON JAN 23 2023 - 12Z FRI JAN 27 2023
...TWO WELL ORGANIZED LOWS WILL BRING RAIN AND INLAND SNOW FROM
THE CENTRAL PLAINS TO THE NORTHEAST STATES...
..SYNOPTIC OVERVIEW
THE WEATHER PATTERN IS EXPECTED TO BE ACTIVE BUT PROGRESSIVE
ACROSS MUCH OF THE NATION GOING INTO NEXT WEEK WITH TWO WELL
DEFINED LOW PRESSURE SYSTEMS OF INTEREST. THE FIRST WILL BE
AFFECTING THE NORTHEAST U.S. GOING THROUGH MONDAY AND THEN EXITING
INTO SOUTHEAST CANADA BY TUESDAY, WITH COASTAL RAIN AND INLAND
SNOW. MEANWHILE, THE NEXT LOW WILL BE GATHERING STRENGTH ACROSS
THE SOUTH-CENTRAL U.S. EARLY IN THE WEEK AND THEN TRACK IN A
GENERAL NORTHEASTERLY DIRECTION ACROSS THE OHIO VALLEY AND THEN
THE GREAT LAKES BY WEDNESDAY AND INTO THURSDAY. A BUILDING WEST
COAST/WESTERN CANADA UPPER RIDGE AS A +PNA PATTERN TRIES TO
DEVELOP WILL HERALD A RETURN TO COLDER CONDITIONS ACROSS MUCH OF
THE CENTRAL AND EASTERN U.S. AS A BROAD UPPER TROUGH DEVELOPS
DOWNSTREAM OF THIS RIDGE.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 00Z GUIDANCE HAS IMPROVED ITS OVERALL SYNOPTIC SCALE DEPICTION
ACROSS THE CONTINENTAL U.S. THROUGH THE MIDDLE OF THE WEEK,
ALTHOUGH THE UKMET WAS SLOWER AND FARTHER SOUTH THAN THE MODEL
CONSENSUS WITH THE DEVELOPING LOW ACROSS THE SOUTH-CENTRAL U.S.
MIDWEEK. THIS LEAD TO MORE WEIGHTING TOWARDS A CMC/ECMWF/GFS
CONSENSUS FOR FRONTS AND PRESSURES, AND AN INCREASE OF THE
ENSEMBLE MEANS UP TO ABOUT 50% BY FRIDAY TO ACCOUNT FOR INCREASING
MESOSCALE UNCERTAINTIES. THE AXIS OF HEAVIEST QPF WITH THE
MIDWEEK STORM SYSTEM HAS NOW SHIFTED TO THE NORTHWEST COMPARED TO
THE PREVIOUS FORECAST CYCLE ACROSS THE DEEP SOUTH AND TENNESSEE
RIVER VALLEY WITH A FARTHER INLAND TRACK OF THE SURFACE LOW.
..WEATHER/HAZARD HIGHLIGHTS
THE FIRST STORM SYSTEM OF NOTE WILL BE AN INTENSIFYING SURFACE LOW
NEAR EASTERN NEW ENGLAND ON MONDAY MORNING THAT WILL QUICKLY LIFT
NORTHWARD ACROSS THE SOUTHEASTERN PROVINCES OF CANADA BY TUESDAY.
THIS IS EXPECTED TO PRODUCE A SWATH OF MODERATE SNOW FROM VERMONT
TO MAINE, AND A WIND-DRIVEN RAIN CLOSER TO THE COAST WITH GUSTS
OVER 40 MPH AT TIMES. HIGH PRESSURE WILL BRIEFLY SETTLE IN ACROSS
THE EASTERN U.S. BEFORE THE NEXT ORGANIZED LOW PRESSURE SYSTEM
ARRIVES. THIS IS FORECAST TO DEVELOP OVER THE GULF COAST REGION
AROUND TUESDAY AND THEN TRACK NORTHEAST ACROSS THE OHIO VALLEY AND
THEN THE GREAT LAKES THROUGH MID WEEK, AND THEN REACHING THE
NORTHEAST U.S. BY THURSDAY. THE BEST HEAVY RAINFALL POTENTIAL
EXISTS OVER THE SOUTHEAST AND SOUTHERN APPALACHIANS, AND A BAND OF
WINTRY WEATHER FROM THE CENTRAL PLAINS NORTHEASTWARD INTO INTERIOR
NEW ENGLAND. ACROSS THE WEST, RAIN AND MOUNTAIN SNOW OF MOSTLY
LIGHT TO MODERATE AMOUNTS SHOULD EXTEND SOUTH-SOUTHEAST ACROSS THE
ROCKIES AND NEARBY AREAS WITH UPPER TROUGH/LOW SUPPORT AND LOWER
LEVEL UPSLOPE FLOW.
TEMPERATURES ARE EXPECTED TO GENERALLY BE ON THE ORDER OF 5 TO 15
DEGREES BELOW AVERAGE FROM THE INTERMOUNTAIN WEST TO THE WESTERN
HIGH PLAINS FOR EARLY IN THE WEEK, AND SLIGHTLY ABOVE AVERAGE
ACROSS MOST OF THE EASTERN U.S. BY THE END OF THE WEEK, MOST
AREAS ACROSS THE NATION SHOULD BE BETWEEN AVERAGE AND 10 DEGREES
BELOW AVERAGE AS BROAD UPPER TROUGH AND CYCLONIC FLOW ALOFT KEEP
ANY ANOMALOUS WARMTH AWAY.
HAMRICK
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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