103
FXUS02 KWBC 161748
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
147 PM EDT MON OCT 16 2023
VALID 12Z THU OCT 19 2023 - 12Z MON OCT 23 2023
..OVERVIEW
GUIDANCE CONTINUES TO SUPPORT A STRONG UPPER RIDGE OVER THE WEST
PERSISTING THROUGH FRIDAY WHICH SUPPORTS EASTERN U.S. TROUGH
AMPLIFICATION AND A LIKELIHOOD FOR DEEPENING LOW PRESSURE OVER THE
NORTHEAST THIS WEEKEND. BEHIND THIS SYSTEM EXPECT THE WESTERN U.S.
RIDGE TO DEAMPLIFY/SHIFT EAST INTO THE PLAINS/MISSISSIPPI VALLEY
BY THE START OF NEXT WEEK WHILE A PACIFIC TROUGH OF MODERATE DEPTH
MOVES INTO THE WEST AND BRINGS PRECIPITATION INTO THE PACIFIC
NORTHWEST AND NORTHERN ROCKIES BY SATURDAY NIGHT. THE FORECAST
PATTERN WILL FAVOR A BROAD AREA OF ABOVE NORMAL TEMPERATURES OVER
THE WEST AND INTO THE PLAINS LATE THIS WEEK, FOLLOWED BY A COOLER
TREND OVER THE WEST AS THE UPPER TROUGH ARRIVES. WITH THE
EXCEPTION OF ABOVE NORMAL READINGS OVER NEW ENGLAND LATE THIS
WEEK, MOST OF THE EAST SHOULD SEE NEAR TO BELOW AVERAGE HIGHS FOR
MOST OF THE PERIOD.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
CONFIDENCE IS HIGH ON THE AMPLIFIED WESTERN RIDGE WITH DEVELOPING
EASTERN TROUGH, BUT UNCERTAINTY STILL PERSISTS ON THE EVOLUTION OF
THE EASTERN TROUGH. THE 00Z ECMWF/06Z GFS (AND NOW 12Z GFS) GET TO
A CLOSED LOW OVER THE NORTHEAST BY 12Z SUNDAY, BUT THROUGH
SLIGHTLY DIFFERENT ROUTES. THE ECMWF DIGS A DEEPER EASTERN TOUGH,
WELL INTO THE SOUTHEAST THURSDAY NIGHT, WHILE THE GFS/CMC/UKMET
ARE NOT AS MERIDIONAL. THE ECMWF HAS MUCH MORE SEPARATION BETWEEN
TWO WAVES THAT CROSS THE EAST AND EVENTUALLY PHASE INTO THE
NORTHEAST LOW WHILE THE GFS IS QUICKER TO DEVELOP A MIDWEST CLOSED
LOW THAT THEN TRACKS TO THE NORTHEAST BY SATURDAY NIGHT. HOWEVER,
THE CMC AND UKMET DO NOT FEATURE A NORTHEAST LOW BY SUNDAY AND ARE
MORE OFFSHORE/PROGRESSIVE. THE 00Z ECENS/06Z GEFS ENSEMBLE MEANS
ARE IN LINE WITH THE DETERMINISTICS, LENDING CREDENCE TO THEIR
SOLUTIONS. GIVEN THE WAY THE ECM/GFS COME TO A SIMILAR SOLUTION
VIA DIFFERENT PATHS, THOSE TWO DETERMINISTIC RUNS DOMINATE THE WPC
MODEL BLEND (BECOMING MORE RELIANT ON THE ECENS/GEFS FOR DAYS 6/7)
AS WELL AS THE QPF.
WITH A NUMBER OF SHORTWAVE TROUGHS TRACKING/INTERACTION AT PLAY,
THERE REMAINS UNCERTAINTY WITH THE STRENGTH/TRACK/TIMING OF EAST
COAST LOW PRESSURE. FOR THE MOST PART, THE UPPER TROUGH ENTERING
THE WEST SATURDAY NIGHT REMAINS BETTER BEHAVED THAN THE EASTERN
SYSTEM WITH A FAVORING OF A ECMWF/GFS SOLUTION THERE GIVEN STRONG
AGREEMENT IN TIMING AND AMPLITUDE.
..WEATHER/HAZARDS HIGHLIGHTS
THERE ARE NO RISK AREAS DEPICTED IN THE DAYS 4-5 EXCESSIVE
RAINFALL OUTLOOKS THAT COVER THE THURSDAY THROUGH FRIDAY NIGHT
TIME FRAME.
THE FRONT EXTENDING SOUTH/SOUTHWEST FROM GREAT LAKES LOW PRESSURE
LATE THIS WEEK WILL PRODUCE AREAS OF RAINFALL OF VARYING
INTENSITY, WITH SOME CONTINUED UNCERTAINTY OVER PRECISE COVERAGE
AND AMOUNTS. MOISTURE AND INSTABILITY STILL DO NOT APPEAR
SUFFICIENT TO YIELD A MEANINGFUL POTENTIAL FOR INTENSE RAIN RATES
THROUGH THURSDAY. ON FRIDAY, MOISTURE/INSTABILITY COULD INCREASE
ENOUGH OVER THE CAROLINA COAST FOR HEAVY RAINFALL AND ON FRIDAY
NIGHT OVER THE NORTHERN MID-ATLANTIC/SOUTHERN NEW ENGLAND
DEPENDING ON THE TRACK OF THE DEVELOPING LOW PRESSURE. HOWEVER,
CONFIDENCE ON MAGNITUDE AND LOCATION IS TOO LOW AT THIS TIME TO
DEFINE ANY RISK AREA YET. GOING INTO SATURDAY, THE MOST LIKELY
FORECAST SCENARIO WOULD HAVE INCREASINGLY HEAVY RAINFALL AND
STRENGTHENING WINDS OVER THE NORTHEAST WITH BRISK TO STRONG WINDS
CONTINUING THROUGH AT LEAST SUNDAY. DEPENDING ON SYSTEM
EVOLUTION/TRACK, HIGHEST ELEVATIONS COULD SEE A LITTLE SNOW.
MUCH OF THE WEST WILL BE DRY INTO THIS WEEKEND. THE UPPER
TROUGH/LEADING SURFACE FRONT MOVING INTO THE REGION SHOULD BRING
LIGHT TO PERHAPS ISOLATED MODERATE RAINFALL TO THE PACIFIC
NORTHWEST SATURDAY NIGHT, WITH THIS MOISTURE SHIFTING ACROSS THE
INTERMOUNTAIN WEST INTO MONDAY. SOME OF THE PRECIPITATION SHOULD
FALL AS SNOW IN THE HIGHER NORTHERN ROCKIES.
A BROAD AREA OF TEMPERATURES 10 TO 20 DEGREES ABOVE NORMAL
CONTINUES EXTEND ACROSS THE WEST INTO THE PLAINS INTO THIS
WEEKEND, DIMINISHING/BECOMING BELOW NORMAL FROM WEST TO EAST AS
THE UPPER TROUGH MOVES INTO THE PACIFIC NORTHWEST OVER THE
WEEKEND. A HANDFUL DAILY HIGH TEMPERATURES ARE FORECAST WEST OF
THE ROCKIES FRIDAY WITH MANY MORE RECORD HIGH MINIMUM TEMPERATURES
FORECAST FOR FRIDAY AND SATURDAY, MAINLY OVER CALIFORNIA.
TEMPERATURES COULD CHALLENGE RECORD HIGHS OVER PARTS OF SOUTHERN
TEXAS FRIDAY INTO THE WEEKEND. THE WARMTH OVER THE CENTRAL U.S.
WILL ALSO DECREASE IN COVERAGE BY THE START OF NEXT WEEK AS THE
UPPER RIDGE LOSES AMPLITUDE. MEANWHILE OVER THE EAST, NEW ENGLAND
WILL SEE 5 TO 10 DEGREE ABOVE NORMAL TEMPERATURES FRIDAY/SATURDAY
WITH THE REST OF THE EASTERN U.S. SEEING A RETURN OF COOLER THAN
NORMAL HIGHS FRIDAY ONWARD WITH THE AMPLIFIED UPPER TROUGH
CROSSING THE REGION.
JACKSON
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page