433
FXUS02 KWBC 141902
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
302 PM EDT MON OCT 14 2024
VALID 12Z THU OCT 17 2024 - 12Z MON OCT 21 2024
..OVERVIEW
DEEP UPPER TROUGHING WITH A LIKELY CLOSED LOW IN THE WEST WILL
LEAD TO A COOL AND WET PATTERN THERE, INCLUDING HIGHER ELEVATION
SNOW AND FROST/FREEZE CONCERNS IN SOME OF THE VALLEYS. HEAVY RAIN
CHANCES COULD INCREASE IN THE SOUTHERN/CENTRAL PLAINS BY THE
WEEKEND. UPPER RIDGING AHEAD OF THIS TROUGH WILL PROMOTE WARMER
THAN AVERAGE TEMPERATURES IN THE NORTHERN/CENTRAL PLAINS TO MIDWEST
AS IT GRADUALLY MOVES EAST, EVENTUALLY DISPLACING THE CHILLY UPPER
TROUGH AND SURFACE HIGH IN THE EAST BY THE WEEKEND.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE CONTINUES TO BE AGREEABLE ON THE LARGE SCALE
PATTERN EVOLUTION THROUGH MUCH OF THE PERIOD, BUT SOME
UNCERTAINTIES STILL IN THE TIMING AND DETAILS OF INDIVIDUAL
SYSTEMS. MOST NOTABLE SYSTEM DURING THE MEDIUM RANGE WILL BE A
SHORTWAVE DIVING INTO THE WEST EARLY PERIOD, WITH MODELS NOW
SHOWING AGREEMENT ON A DEEP CLOSED LOW DEVELOPING OVER THE
SOUTHWEST BY THIS WEEKEND AND EVENTUALLY LIFTING NORTH AND EAST
EARLY NEXT WEEK. THROUGH THE 00Z RUN, THE CMC WAS MORE PROGRESSIVE
AND DISPLACED EAST OF THE GFS, ECMWF, AND UKMET, BUT THE NEW 12Z
RUN TODAY DID JUMP WEST. 00Z GFS WAS QUICKEST TO LIFT THE SYSTEM
NORTHWARD SUNDAY-MONDAY BUT THE NEW 12Z RUN DID SLOW DOWN. GOOD
AGREEMENT ON AN UPPER RIDGE BUILDING BACK IN ACROSS THE EAST AGAIN
BEHIND A DEPARTING UPPER TROUGH/LOW, BUT HOW FAR WESTWARD THIS
RIDGE RETROGRADES EARLY NEXT WEEK IS DEPENDENT ON THE EVOLUTION OF
THE WESTERN/CENTRAL UPPER LOW.
WPC FORECAST FOR TODAY PREFERRED A NON-CMC BLEND EARLY IN THE
PERIOD, WHICH WAS MORE WEST WITH THE LOW AND MOST CONSISTENT WITH
THE PREVIOUS WPC FORECAST. LEANED MORE HEAVILY ON THE ENSEMBLE
MEANS LATE PERIOD WITH LINGERING AND INCREASING UNCERTAINTIES.
..WEATHER/HAZARDS HIGHLIGHTS
THE UPPER TROUGH/LOW PUSHING ACROSS THE WEST LATER WEEK WILL PUSH
PRECIPITATION FROM THE PACIFIC NORTHWEST INTO THE INTERMOUNTAIN
WEST/ROCKIES LATER WEEK, WITH ENHANCED PRECIPITATION TOTALS IN
TERRAIN. HIGHER ELEVATION SNOW IS LIKELY, WHICH WILL BE THE FIRST
SNOW OF THE SEASON IN SOME LOCATIONS GIVEN THE WARM FALL IN THE
WEST THUS FAR. SOME RAIN AND SNOW COULD CONTINUE ACROSS THE
CENTRAL/SOUTHERN ROCKIES INTO THE WEEKEND. MEANWHILE, GULF MOISTURE
MAY STREAM IN JUST AHEAD OF THE UPPER LOW FOR INCREASING RAIN
CHANCES IN THE CENTRAL/SOUTHERN HIGH PLAINS LATE WEEK INTO THE
WEEKEND. WHILE FORECAST DETAILS VARY, RECENT MODELS SHOW SOME
MODERATE TO LOCALLY HEAVY RAIN POTENTIAL, PARTICULARLY FOR
SENSITIVE BURN SCAR LOCATIONS. LIGHTER RAIN MAY SPREAD INTO THE
NORTH- CENTRAL U.S. LATE WEEK TOO ALONG THE FRONT. MORE ROUNDS OF
PRECIPITATION ARE LIKELY FOR THE PACIFIC NORTHWEST INTO THE WEEKEND
WITH ADDITIONAL IMPULSES COMING THROUGH.
MEANWHILE, THE EASTERN U.S. IS FORECAST TO BE GENERALLY DRY LATE
WEEK INTO EARLY NEXT WEEK, WITH THE EXCEPTION OF PARTS OF THE
FLORIDA PENINSULA. THERE, RETURN FLOW OF MOISTURE NORTH OF A
STATIONARY FRONT COULD INCREASE RAIN AND THUNDERSTORM CHANCES
ESPECIALLY FOR SOUTH FLORIDA BY FRIDAY AND PERHAPS SPREADING
NORTHWARD INTO THE WEEKEND. MODELS CONTINUE TO VARY ON HOW MUCH
RAIN MAY FALL ONSHORE VERSUS OFFSHORE, SO NO AREA IS CURRENTLY
DELINEATED IN THE DAY 5/FRIDAY ERO, BUT THERE MAY BE A NONZERO
CHANCE FOR FLASH FLOODING ESPECIALLY IF HEAVY RAIN RATES OCCUR IN
THE SENSITIVE URBAN AREAS.
AN UPPER RIDGE ALIGNED OVER THE MISSISSIPPI VALLEY THURSDAY AND
SHIFTING INTO THE EAST FRIDAY WILL PROMOTE WELL ABOVE NORMAL
TEMPERATURES IN ITS VICINITY. THE BIGGEST ANOMALIES ARE FORECAST
ACROSS THE NORTH-CENTRAL PLAINS ON THURSDAY, WHERE HIGHS INTO THE
70S AND 80S ARE 15-25 DEGREES ABOVE AVERAGE FOR MID-OCTOBER. COOLER
THAN AVERAGE TEMPERATURES BY 10-15 DEGREES ARE EXPECTED TO
CONTINUE ACROSS THE EASTERN THIRD OF THE U.S. INTO THURSDAY UNDER
COOL HIGH PRESSURE. ANOTHER ROUND OF CHILLY MORNING LOWS MAY CAUSE
FROST/FREEZE CONCERNS FROM THE GREAT LAKES REGION INTO THE
NORTHEAST/APPALACHIANS. GRADUAL MODERATION/WARMING IS LIKELY THERE
FRIDAY AND EVEN MORE SO INTO THE WEEKEND WHEN UPPER RIDGING COMES
OVERHEAD, FOR TEMPERATURES AROUND 5-10 DEGREES ABOVE NORMAL IN THE
NORTHEASTERN TIER. THEN THE RIDGE REBUILDING OVER THE CENTRAL U.S.
EARLY NEXT WEEK WILL LEAD TO WARMER THAN AVERAGE TEMPERATURES IN
THE NORTHERN PLAINS TO UPPER MIDWEST ONCE AGAIN. ON THE OTHER HAND,
THE UPPER TROUGH AND FRONTAL SURGES IN THE WEST WILL CAUSE BELOW
NORMAL TEMPERATURES SPREADING ACROSS THE WEST COAST TO GREAT
BASIN/INTERMOUNTAIN WEST AND SOUTHWEST PARTICULARLY THROUGH LATE
WEEK. THESE COLDER TEMPERATURES MAY ALSO LEAD TO ADDITIONAL
FROST/FREEZE CONCERNS FOR ANY STILL SUSCEPTIBLE GROWING
AREAS/VALLEY LOCATIONS.
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 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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