532
FXUS02 KWBC 200659
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 AM EDT THU OCT 20 2022
VALID 12Z SUN OCT 23 2022 - 12Z THU OCT 27 2022
..OVERVIEW
UPPER LEVEL TROUGHING WILL BE ESTABLISHED ACROSS THE WEST AS THE
MEDIUM RANGE PERIOD BEGINS SUNDAY AND SHOULD SHIFT INTO THE
CENTRAL U.S. AS THE WEEK PROGRESSES, THOUGH UNCERTAINTY REMAINS
WITH THE DETAILS DUE TO MODEL VARIATIONS WITH HANDLING A SOUTHERN
STREAM UPPER LOW AND ITS POTENTIAL PHASING WITH THE NORTHERN
STREAM TROUGH. BUT THERE IS GENERAL AGREEMENT THAT PRECIPITATION
WILL SPREAD FROM THE WESTERN U.S. SUNDAY INTO THE CENTRAL U.S.
THROUGH MONDAY-TUESDAY ALONG A STRONG COLD FRONT, WITH SNOW LIKELY
IN THE ROCKIES AND PERHAPS EVEN INTO THE NORTHERN HIGH PLAINS ON
THE BACKSIDE OF A SURFACE LOW AS COOLER TEMPERATURES SPREAD BEHIND
THE FRONT. THERE IS ALSO POTENTIAL FOR MODERATE TO HEAVY RAIN
FARTHER SOUTH, BUT WITH CONSIDERABLE DIFFERENCES IN THE PLACEMENT
OF HEAVIEST RAIN. MEANWHILE RAIN IS BECOMING MORE LIKELY FOR
PORTIONS OF THE MID-ATLANTIC TO NORTHEAST EARLY NEXT WEEK WITH A
SMALLER SCALE UPPER LOW AND A SLOW-MOVING FRONTAL SYSTEM JUST
OFFSHORE. LIGHTER RAIN COULD THEN SHIFT INTO THE EAST MIDWEEK JUST
AHEAD OF THE COLD FRONT AND UPPER TROUGH, WHILE ANOTHER ROUND OR
TWO OF PRECIPITATION IS POSSIBLE ACROSS THE NORTHWEST.
..MODEL AND PREDICTABILITY ASSESSMENT
WHILE MODEL GUIDANCE STARTS OUT WITH DECENT AGREEMENT FOR
TROUGHING ACROSS THE WEST, THERE ARE STILL CONSIDERABLE
DIFFERENCES FOR THE DAYS 3-5 FORECAST PERIOD WITH THE POTENTIAL
FOR INTERACTION AND POSSIBLE PHASING OF THIS NORTHERN STREAM
TROUGH WITH SOUTHERN STREAM ENERGY STARTING NEAR BAJA CALIFORNIA
SUNDAY/DAY 3. ECMWF RUNS HAVE REMAINED ON THE NOT PHASED SIDE OF
THE GUIDANCE ENVELOPE, KEEPING A SEPARATE CLOSED LOW SLOWLY MOVING
ACROSS NORTHERN MEXICO WHILE THE NORTHERN STREAM TROUGH AND THUS
THE FRONT TRACK FORWARD A LITTLE FASTER, ALONG WITH LESS QPF IN
THE SOUTH-CENTRAL CONUS. CONVERSELY, THE CMC AND UKMET RUNS TEND
TO PHASE THE FEATURES IMMEDIATELY AND MOVE ONE TROUGH MORE SLOWLY
ACROSS THE WESTERN/CENTRAL U.S. (FOR A FARTHER WEST HEAVY RAINFALL
AXIS AS WELL). GFS RUNS HAVE BEEN WAFFLING OVER THE PAST COUPLE OF
DAYS BUT THE 12/18Z RUNS SEEMED TO BE A FAIR MIDDLE GROUND BETWEEN
THESE SOLUTIONS. THUS FAVORED THE GFS RUNS ALONG WITH A HEALTHY
PROPORTION OF THE GEFS AND EC ENSEMBLE MEANS FOR THE
FRONTS/PRESSURES FORECAST. ON THE POSITIVE SIDE, AT LEAST THESE
DIFFERENCES OF TROUGH TIMING DUE TO NORTHERN/SOUTHERN STREAM
INTERACTION ARE NOT AS BAD AS THEY HAD BEEN, BUT STILL FAIRLY
DISAGREEABLE FOR THE FORECAST LEAD TIME. THERE IS ALSO SOME BETTER
AGREEMENT FOR ENERGY MOVING NORTHWARD NEAR THE EAST COAST AND AN
ASSOCIATED FRONT/LOW SYSTEM AT THE SURFACE SPREADING SOME RAINFALL
ONSHORE EARLY NEXT WEEK. FOR BOTH THIS AREA AND QPF ACROSS THE
CENTRAL U.S., THE WPC FORECAST TRENDED WETTER FROM CONTINUITY BUT
NOT AS HIGH AS THE 01Z NBM, FOR A SMOOTHER TRANSITION OF AN
INCREASING FORECAST. THEN WHILE THERE IS GENERAL AGREEMENT FOR THE
TROUGH TO TRACK EASTWARD THROUGH THE MIDDLE PART OF NEXT WEEK,
THERE ARE DIFFERENCES IN THE DETAILS WITH THE AMPLITUDE, WHILE
THERE ARE ALSO MODEL DIFFERENCES UPSTREAM WITH ADDITIONAL
TROUGHING COMING INTO THE WEST WITH POSSIBLE RIDGING IN BETWEEN.
UTILIZED MORE THAN HALF ENSEMBLE MEANS FOR THE FRONTS/PRESSURES
FORECAST BLEND BY DAYS 6-7 GIVEN THE REMAINING DIFFERENCES.
..SENSIBLE WEATHER AND POTENTIAL HAZARDS
PRECIPITATION IS FORECAST TO CONTINUE ACROSS THE ROCKIES EARLY
NEXT WEEK IN THE FORM OF SNOW AT HIGHER ELEVATIONS. AS A SURFACE
LOW PRESSURE SYSTEM STRENGTHENS AND TRACKS ACROSS THE PLAINS, THE
NORTHERN HIGH PLAINS EVEN IN LOWER ELEVATIONS MAY ALSO SEE NOTABLE
EARLY SEASON SNOW TO THE NORTHWEST OF THE LOW. GUSTY WINDS COULD
ALSO BE A THREAT WITH THIS REASONABLY STRONG LOW. FARTHER SOUTH
ALONG AND AHEAD OF THE COLD FRONT, MOISTURE STREAMING IN FROM THE
GULF WILL LEAD TO RAIN CHANCES INCREASING ACROSS THE CENTRAL PART
OF THE COUNTRY. ENHANCED TO POSSIBLY HEAVY RAINFALL IS LIKELY IN
THE SOUTH-CENTRAL U.S., BUT THE PLACEMENT OF HEAVIEST RAIN VARIES
IN THE MODEL GUIDANCE ACROSS THE SOUTHERN HALF OF THE PLAINS INTO
THE MISSISSIPPI VALLEY. AS THE COLD FRONT AND UPPER TROUGH TRACK
EASTWARD, RAIN CHANCES ARE EXPECTED TO SHIFT TOWARD THE EAST BUT
WITH LIKELY LIGHTER RAINFALL AMOUNTS. MORE ENHANCED RAINFALL
TOTALS ARE ACTUALLY FORECAST IN THE EAST EARLIER IN THE WEEK, WHEN
UPPER ENERGY AND A LOW PRESSURE SYSTEM JUST OFFSHORE INTO THE
ATLANTIC WILL PROVIDE SUPPORT FOR RAIN. THERE IS BETTER AGREEMENT
FOR RAIN TO FALL ONSHORE NOW THAN THERE HAD BEEN THE PAST FEW
DAYS, BUT STILL WITH SOME UNCERTAINTY IN EXACT PLACEMENT.
COASTAL/SOUTHEASTERN NEW ENGLAND APPEARS TO HAVE THE GREATEST
CHANCE OF RECEIVING RAIN FROM THIS SYSTEM DUE TO ITS GEOGRAPHIC
PROTRUSION INTO THE ATLANTIC, BUT THE INTERIOR NORTHEAST AND
COASTAL MID-ATLANTIC COULD SEE SOME RAIN AS WELL. ADDITIONALLY, A
PARADE OF FRONTS COMING INTO THE NORTHWEST WILL SUPPORT ADDITIONAL
PRECIPITATION CONTINUING/REFORMING THERE THROUGH MUCH OF NEXT WEEK.
TEMPERATURES ARE LIKELY TO BE WARMER THAN AVERAGE ACROSS THE
MID-SECTION OF THE COUNTRY UP INTO THE GREAT LAKES CONTINUING INTO
SUNDAY WITH SOUTHERLY FLOW STRENGTHENING AHEAD OF THE WESTERN
UPPER TROUGH. HIGHS AND LOWS OF 10-254F ABOVE NORMAL WILL BE
WIDESPREAD ACROSS PARTS OF THE PLAINS AND MIDWEST. MEANWHILE, AN
AREA OF BELOW NORMAL TEMPERATURES WILL EXPAND FROM THE WEST ON
SUNDAY TOWARD THE NORTH-CENTRAL U.S. MONDAY-TUESDAY AS THE UPPER
TROUGH AND COLD FRONT(S) MOVE THROUGH, WITH LOWS AROUND 5-15F
BELOW AVERAGE AND HIGHS 10-20F BELOW AVERAGE. THIS WILL PUSH
WARMER THAN AVERAGE TEMPERATURES INTO THE NORTHEASTERN U.S. BY
MONDAY-WEDNESDAY, WITH THE EAST-CENTRAL U.S. RETURNING TO AROUND
NORMAL TEMPERATURES BEHIND THE COLD FRONTAL PASSAGE.
TATE
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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