163
FXUS02 KWBC 141900
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 PM EST THU NOV 14 2024
VALID 12Z SUN NOV 17 2024 - 12Z THU NOV 21 2024
..HEAVY RAINFALL THREAT FOR THE CENTRAL U.S EARLY NEXT WEEK
...TROPICAL STORM SARA TO BRING UNCERTAIN HEAVY RAINFALL/RUNOFF
THREATS FROM THE CENTRAL GULF COAST TO FLORIDA TUESDAY/WEDNESDAY...
..OVERVIEW
UPPER TROUGHING OVER THE WEST BY THIS COMING WEEKEND WILL SPLIT
SENDING NORTHERN STREAM ENERGY THROUGH THE NORTHERN PLAINS/UPPER
MIDWEST, WHILE A SOUTHERN STREAM CUTOFF LOW SHIFTS ACROSS THE FOUR
CORNERS REGION AND INTO THE CENTRAL U.S. NEXT WEEK. THIS IS NOW
SLATED TO BE EJECTED BY A DYNAMIC UPPER TROUGH WORK DIGGING FROM THE
NORTHWEST MONDAY TO AROUND THE SOUTH-CENTRAL U.S. NEXT MIDWEEK.
AT THIS SURFACE, THIS WILL TRANSLATE TO EARLY WEEK CYCLOGENESIS IN
THE LEE OF THE ROCKIES WITH A DEEPENING STORM SYSTEM TRACKING FROM
THE SOUTHERN PLAINS THROUGH THE MIDWEST MONDAY- NEXT THURSDAY.
THIS PATTERN WOULD SUPPORT HEAVY RAINFALL POTENTIAL FROM THE SOUTH-
CENTRAL PLAINS INTO THE MISSISSIPPI VALLEY BY LATE THIS WEEKEND
INTO EARLY NEXT WEEK, WITH SOME SNOW POSSIBLE ON THE BACKSIDE OF
THE LOW ACROSS THE UPPER MIDWEST, BUT DEPENDENT ON THE QUALITY OF
COLD AIR FILTERING IN BEHIND THIS SYSTEM. MEANWHILE, NHC GUIDANCE
SHOWS TROPICAL STORM SARA EMERGING OUT OF THE CARIBBEAN/YUCATAN AND
INTO THE EAST-CENTRAL GULF OF MEXICO NEXT WEEK, WITH POTENTIAL BUT
STILL UNCERTAIN HEAVY RAINFALL/RUNOFF THREATS POSSIBLE FROM THE
CENTRAL GULF COAST TO FLORIDA, WITH LEAD ACTIVITY ENHANCED BY DEEP
MOISTURE FEED INTO AN APPROACHING MID-LATITUDE FRONT THAT MAY
MERGE WITH INCREASINGLY EXTRATROPICAL SARA OVER/OFF THE SOUTHEAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE WPC MED-RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM A
COMPOSITE BLEND OF REASONABLY WELL CLUSTERED GUIDANCE FROM THE
GFS/ECMWF/UMKET/CANADIAN, THE NATIONAL BLEND OF MODELS AND WPC
CONTINUITY VALID FOR SUNDAY/MONDAY. THIS SOLUTION HAS GOOD ENSEMBLE
SUPPORT AS WELL. CYCLE TO CYCLE GUIDANCE CONTINUITY IS NOT STELLAR
FOR LATER NEXT WEEK HOWEVER IN A PATTERN WITH INCREASING FORECAST
SPREAD AND UNCERTAINTY, LENDING AN ENSEMBLE FORECAST APPROACH.
OPTED TO LEAN ON ECMWF/CANADIAN ENSEMBLES THAT ARE MORE IN LINE
WITH LATEST MODEL TRENDS AND LATEST GUIDANCE FROM THE NHC ON SARA.
..WEATHER/HAZARDS HIGHLIGHTS
THE COVERAGE AND INTENSITY OF PRECIPITATION ACROSS PORTIONS OF THE
FOUR CORNER TO THE SOUTHERN/CENTRAL PLAINS/MID-MISSISSIPPI VALLEY
WILL INCREASE OVER THE WEEKEND; WHICH WILL BOOST THE THREAT FOR
HEAVY RAIN FOR THE SOUTH-CENTRAL PLAINS/MID-MISSISSIPPI VALLEY FOR
THE START OF THE WEEK. GIVEN THE DEGREE OF SPREAD AMONGST THE
GUIDANCE, SPECIFICS FOR AMOUNTS, LOCATION AND DEGREE OF IMPACTS
REMAIN VERY UNCERTAIN; HOWEVER THERE CONTINUES TO BE A SIGNAL
FOCUSING IN THE VICINITY OF NORTHERN TEXAS INTO OKLAHOMA AND BACK
TOWARDS THE SOUTHERN HIGH PLAINS WHERE A MARGINAL RISK IS IN PLACE
ON THE DAY 4/SUNDAY EXCESSIVE RAINFALL OUTLOOK. THE HEAVY RAIN
THREAT LIFTS NORTHEASTWARD ON MONDAY, BUT WITH UNCERTAINTY ON
EXACTLY WHERE THE GREATEST THREAT LIES. FOR NOW, THE DAY 5/MONDAY
ERO HIGHLIGHTS A BROAD MARGINAL RISK SPANNING ACROSS MUCH OF THE
CENTRAL PLAINS INTO PARTS OF THE MID TO UPPER MISSISSIPPI VALLEY.
DEPENDING ON COLD AIR FILTERING IN BEHIND THE DEEPENING STORM
SYSTEM, SOME ACCUMULATING SNOW MAY BE POSSIBLE ACROSS THE ROCKIES
INTO THE NORTHERN PLAINS EARLY-MID NEXT WEEK IN A PATTERN WITH
POTENTIAL FOR HIGH WINDS. GENERALLY WET CONDITIONS IS EXPECTED TO
ACCOMPANY THE COLD FRONT LATE PERIOD AS IT PUSHES TO THE EAST-
CENTRAL STATES AND TO THE EAST.
OUT WEST, AN ATMOSPHERIC RIVER IS EXPECTED TO SUPPORT MODERATELY HEAVY
RAIN AND MOUNTAIN SNOWS ACROSS THE PACIFIC NORTHWEST THROUGH
SUNDAY, WITH MODEST PRECIPITATION EXTENDING INLAND ACROSS THE WEST
WITH SYSTEM/PATTERN TRANSLATION. WPC IS MAINTAINING THE MARGINAL
RISK FOR THE DAY 4 ERO ACROSS WESTERN WASHINGTON AND OREGON. THIS
SYSTEM ALSO OFFERS AN OPPORTUNITY FOR MORE DYNAMICALLY ENHANCED
MOUNTAIN SNOWS OVER FAVORED TERRAIN NEAR THE TRACK OVER THE WEST.
DEEP MOISTURE FROM NEWLY FORMED T.S. SARA AS IT EMERGES INTO THE
GULF OF MEXICO MAY BEGIN IMPACTING PARTS OF FLORIDA OR THE GULF
COAST BY EARLY-MID NEXT WEEK, BUT THERE IS A LOT OF UNCERTAINTY IN
EXACT IMPACTS AND AMOUNNTS. THIS SYSTEM NEEDS TO BE MONITORED, BUT
CAN STILL FOCUS A HEAVY RAINFALL THREAT DESPITE NOT BEING FORECAST
TO STRENGTHEN TO HURRICANE STRENGTH.
ABOVE SEASONAL NORMAL TEMPERATURES WILL SPREAD FROM THE CENTRAL
U.S. TO THE EAST BY SUNDAY INTO MONDAY LEADING TO DAILY MAXIMUM
TEMPERATURES TO CLIMB 10 TO 15 DEGREES WARMER IN A SOME LOCATIONS.
FOR THE WESTERN U.S., IT WILL BE TRENDING COOLER AS UPPER TROUGHING
AMPLIFIES OVER THE REGION. WELL BELOW NORMAL TEMPERATURES WILL
PROVIDE A COLD SNAP SPREAD TO THE CENTRAL U.S. NEXT WEEK.
SANTORELLI/SCHICHTEL
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 (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
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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