991
FXUS02 KWBC 201851
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
250 PM 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 PLACEMENT.
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 POTENTIAL
INTERACTION AND POSSIBLE PHASING OF THE NORTHERN STREAM TROUGH
WITH SOUTHERN STREAM ENERGY/CLOSED LOW STARTING NEAR BAJA
CALIFORNIA SUNDAY/DAY 3. THE ECMWF HAS REMAINED CONSISTENT IN
SHOWING LESS/LITTLE PHASING BETWEEN THESE TWO SYSTEMS RESULTING IN
A MUCH FASTER TRACK OF THE NORTHERN STREAM TROUGH AND SLOWER
PROGRESSION OF THE BAJA CALIFORNIA ENERGY INLAND. CONVERSELY, THE
CMC HAVE TENDED TO PHASE THE FEATURES IMMEDIATELY AND HAVE A
DISTINCT CLOSED LOW TRACKING FROM THE SOUTHWEST INTO THE
SOUTH-CENTRAL PLAINS AND MIDWEST MON-WED. PREFER A PREFERENCE AT
THIS POINT IN THE MIDDLE OF THESE TWO SOLUTIONS, CLOSER TO THE GFS
AND UKMET BOTH WHICH SHOW SOME DEGREE OF PHASING BUT NOT AS
QUICKLY OR VIGOROUSLY AS THE CMC, WITH AN AMPLIFIED TROUGH
SHIFTING ACROSS THE CENTRAL U.S.. THIS SOLUTION ALSO SEEMS TO BE
THE BEST PROXY FOR THE MORE MIDDLE GROUND (THOUGH WEAKER) ENSEMBLE
MEANS AND ALSO IS CLOSE TO WPC CONTINUITY.
ELSEWHERE, BETTER AGREEMENT ON ENERGY OFF THE EAST COAST, THOUGH
WITH PLENTY OF LINGERING UNCERTAINTY IN THE DETAILS AND RESULTING
QPF. THE NEXT TROUGH INTO THE WEST AROUND WEDNESDAY SHOWS SOME
TIMING/AMPLITUDE DIFFERENCES MOST LIKELY STEMMING FROM THE
CONSIDERABLE UNCERTAINTY DOWNSTREAM IN THE CENTRAL STATES. A BLEND
TOWARDS THE ENSEMBLE MEANS LATE PERIOD, SEEMS TO WORK WELL RIGHT
NOW.
..SENSIBLE WEATHER AND POTENTIAL HAZARDS
PRECIPITATION IS FORECAST TO CONTINUE ACROSS THE ROCKIES EARLY
NEXT WEEK IN THE FORM OF SNOW, POTENTIALLY HEAVY, 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 AND BLOWING SNOW 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. EARLIER IN THE WEEK, UPPER
ENERGY AND A LOW PRESSURE SYSTEM JUST OFFSHORE INTO THE ATLANTIC
SHOULD PROVIDE SUPPORT FOR RAIN ACROSS ESPECIALLY SOUTHERN NEW
ENGLAND, BUT ALSO MAYBE PARTS OF THE INTERIOR NORTHEAST AND
MID-ATLANTIC. 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. 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 10-25F 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.
SANTORELLI/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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