318
FXUS02 KWBC 252037
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
436 PM EDT WED OCT 25 2023
VALID 12Z SAT OCT 28 2023 - 12Z WED NOV 01 2023
...HEAVY SNOW THREAT FOR THE CENTRAL ROCKIES/ADJACENT PLAINS THIS
WEEKEND...
..ARCTIC SURGE THROUGH THE CENTRAL U.S INTO NEXT WEEK.
..OVERVIEW
IT REMAINS THE CASE THAT RENEWED TROUGHING WILL ENVELOPE THE WEST
THROUGH THE WEEKEND BEFORE SHIFTING INTO PLAINS AND EVENTUALLY THE
EAST NEXT WEEK. INITIAL STRONG RIDGING OVER THE SOUTHEAST THIS
WEEKEND WILL CREATE A PRONOUNCED CONTRAST BETWEEN UNSEASONABLY
WARM WEATHER OVER THE EAST AND AN EXPANSIVE AREA OF MUCH BELOW
NORMAL COLD OVER THE WEST AND THE PLAINS. THIS PATTERN BRINGS A
THREAT FOR HEAVY SNOW TO THE NORTH-CENTRAL ROCKIES AND POSSIBLE
PARTS OF THE HIGH PLAINS WITH A MULTI-DAY PERIOD OF ENHANCED
RAINFALL OVER PARTS OF THE SOUTH-CENTRAL PLAINS TO MIDWEST
SATURDAY AND SUNDAY ALONG A FRONTAL BOUNDARY. UPPER RIDGING SHOULD
BUILD OVER THE WEST AGAIN BY NEXT MIDWEEK AS THE NEXT TROUGH WORKS
INTO THE EAST PACIFIC/WEST COAST.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
06 UTC GFS/GEFS AND 00 UTC UKMET/ECMWF/ECMWF ENSEMBLE MEAN
SOLUTIONS SEEM BEST CLUSTERED AND REASONABLY THROUGH THE UPCOMING
WEEKEND, EVEN WITH LINGERING TIMING ISSUES THAT BECOME MORE
PROMINENT INTO NEXT WEEK. A COMPOSITE BLEND ALONG WITH INPUT FROM
THE 13 UTC NATIONAL BLEND OF MODELS (NBM) SEEMS TO PROVIDE A SOLID
FORECAST BASIS FOR THE WEEKEND. GIVEN GROWING FORECAST SPREAD INTO
NEXT WEEK, OPTED TO SWITCH PREFERENCE CLOSEST TO THE ENSEMBLES AND
THE 00 UTC ECMWF ENSEMBLE MEAN BEST MATCHES WPC PRODUCT CONTINUITY
AND MESSAGING. THE ECMWF ENSEMBLE MEAN CONTINUES TO OFFERS A
SLIGHTLY MORE AMPLIFIED AND LESS PROGRESSIVE SOLUTION OVERALL
COMPARED TO THE GEFS MEAN.
..WEATHER/HAZARDS HIGHLIGHTS
INSTABILITY AND ANOMALOUS MOISTURE ALONG A SLOW MOVING FRONT THIS
WEEKEND WILL PROVIDE FOCUS FOR A MULTI-DAY PERIOD OF HEAVY
RAINFALL FROM PARTS OF THE SOUTH-CENTRAL PLAINS INTO THE
MIDWEST/OHIO VALLEY WITH POTENTIAL FOR REPEAT/TRAINING OF STORMS.
SOME LINGERING UNCERTAINTY ON EXACTLY WHERE THE HEAVIEST TOTALS
SET UP, AND DRY ANTECEDENT CONDITIONS COULD LIMIT A WIDESPREAD
FLASH FLOOD THREAT, BUT LATEST MODEL QPF AMOUNTS COMBINED WITH THE
POTENTIAL FOR ADDITIONAL RAINS OVER THE NEXT FEW DAYS LEADING INTO
THE MEDIUM RANGE FORECAST PERIOD DO SEEM TO STILL SUPPORT A SLIGHT
RISK AREA ON BOTH THE DAYS 4 AND 5 EROS ACROSS THE MID-MISSISSIPPI
VALLEY, WITH A MARGINAL RISK EXTENDING NORTHEAST AND SOUTHWESTWARD
ALONG THE SPAN OF THE FRONTAL BOUNDARY. POTENTIAL EXISTS FOR SOME
SNOW IN THE NORTHERN PERIPHERY OF THE PRECIPITATION SHIELD, BUT
SPECIFICS REMAIN VERY UNCERTAIN AND REQUIRE MONITORING. HOWEVER,
THERE IS A GROWING SIGNAL SUPPORTING A THREAT FOR HEAVY SNOW FOR
THE NORTH-CENTRAL ROCKIES AND INTO THE LESS UNCERTAIN ADJACENT
PLAINS THIS WEEKEND THAT REMAINS DENOTED IN THE WPC WINTER WEATHER
OUTLOOK. THERE IS ALSO SOME POTENTIAL FOR A TRANSITION ZONE OF
FREEZING RAIN/SLEET ON THE LEADING EDGE OF PRECIPITATION DOWN
ACROSS THE SOUTH-CENTRAL PLAINS AND MID-MS VALLEY THIS WEEKEND
INTO MONDAY WITH COLD AIR ADVANCE. BEYOND THAT NEXT WEEK, MUCH OF
THE COUNTRY SHOULD BE MAINLY DRY AS HIGH PRESSURE DOMINATES THE
CONUS. THERE SHOULD BE MODEST LAKE EFFECT RAIN/SNOW SHOWERS
DOWNWIND OF THE GREAT LAKES. OF NOTE IS ALSO AN UNCERTAIN LIFTING
OF A LOW UP FROM THE CARIBBEAN TO THE SOUTHWESTERN ATLANTIC IN
SOME GUIDANCE IN ADVANCE OF A MAIN COLD FRONT THAT IS NOW BEING
MONITORED BY NHC. MEANWHILE, THE APPROACH OF AN AMPLIFIED EASTERN
PACIFIC UPPER TROUGH/HEIGHT FALLS AND SURFACE SYSTEM ENERGIES DOES
OVERALL FAVOR A MODERATELY WETTER PATTERN IN ABOUT A WEEK FOR THE
NORTHWEST.
MUCH BELOW NORMAL TEMPERATURES ACROSS THE WEST INTO THE
NORTHERN/CENTRAL PLAINS ON SATURDAY WILL EXPAND SOUTH AND EASTWARD
BRINGING THE FIRST REAL COLD SNAP OF THE SEASON TO MANY ACROSS THE
CENTRAL U.S., INCLUDING AS FAR SOUTH AS THE SOUTHERN PLAINS/TEXAS
AND COINCIDING WITH OUTDOOR HALLOWEEN FESTIVITIES NEXT TUESDAY.
DAYTIME HIGHS 20-30 DEGREES BELOW NORMAL ARE LIKELY WITH A FEW
DAILY RECORDS POSSIBLE WITHIN THIS COLD AIR MASS. THE CLIMATE
PREDICTION CENTER (CPC) HAS SHOWN AN EXTENSION OF THE COLD AIR
THREAT INTO EARLY NOVEMBER OVER THE CENTRAL STATES AS WELL.
MEANWHILE, WELL ABOVE NORMAL TEMPERATURES WILL CONTINUE INTO THIS
WEEKEND/MONDAY FOR THE SOUTHEAST/EAST UNDERNEATH A RETREATING
UPPER RIDGE. EXPECT A BROAD AREA OF HIGHS 10-20 DEGREES ABOVE
NORMAL WITH SOME MORNING LOWS 20-25 DEGREES ABOVE NORMAL. DAILY
RECORDS ARE POSSIBLE, WITH RECORD WARM LOWS LIKELY TO BE MORE
NUMEROUS THAN RECORD HIGHS. THE CHILLY CENTRAL U.S. AIRMASS SHOULD
PUSH EASTWARD WITH TIME NEXT WEEK (WITH SOME MODERATION) WITH MUCH
OF THE COUNTRY EAST OF THE ROCKIES BELOW NORMAL NEXT
TUESDAY-WEDNESDAY BEHIND THE STRONG COLD FRONT.
SANTORELLI/SCHICHTEL
HAZARDS:
- HEAVY RAIN ACROSS PORTIONS OF THE SOUTH-CENTRAL U.S., SAT-SUN,
OCT 28-29.
- HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN TO CENTRAL ROCKIES,
SAT, OCT 28.
- FROST/FREEZE FROM PORTIONS OF THE SOUTHERN HIGH PLAINS, ACROSS
THE CENTRAL PLAINS AND THROUGH MUCH OF THE MIDWEST, SUN-MON, OCT
29-OCT 30.
- FROST/FREEZE ACROSS PORTIONS OF THE SOUTHERN ROCKIES INTO THE
SOUTHERN HIGH PLAINS, MON-WED, OCT 30-NOV 1.
- FROST/FREEZE FROM THE OZARKS ACROSS THE OHIO AND TENNESSEE
VALLEYS AND INTO THE SOUTHERN APPALACHIANS, TUE-WED, OCT 31-NOV 1.
- HAZARDOUS COLD ACROSS PORTIONS OF THE NORTHERN ROCKIES INTO MUCH
OF THE NORTHERN PLAINS, SAT, OCT 28 AND MON, OCT 30.
- HAZARDOUS COLD ACROSS PORTIONS OF THE CENTRAL ROCKIES INTO THE
CENTRAL PLAINS, SUN-TUE, OCT 29-31.
- FLOODING POSSIBLE OVER PORTIONS OF WISCONSIN, SAT-SUN, OCT 28-29.
- FLOODING OCCURRING OR IMMINENT OVER PORTIONS OF WISCONSIN,
SAT-SUN, OCT 28-29.
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 FORECAST, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY
MESSAGES 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
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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