236
FXUS02 KWBC 121811
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
211 PM EDT SAT OCT 12 2024
VALID 12Z TUE OCT 15 2024 - 12Z SAT OCT 19 2024
..OVERVIEW
AS THE MEDIUM RANGE PERIOD BEGINS TUESDAY, UPPER TROUGHING WILL
SETTLE IN ACROSS THE EASTERN HALF OF THE U.S., LEADING TO BELOW
NORMAL TEMPERATURES ALONG WITH FROST/FREEZE CONCERNS FOR THE NORTH-
CENTRAL U.S. TO NORTHEAST, ALONG WITH LAKE-ENHANCED PRECIPITATION.
MEANWHILE UPPER RIDGING (ASIDE FROM EMBEDDED ENERGY) WILL SET UP
ATOP THE INTERIOR WEST, AND THIS RIDGE IS FORECAST TO SHIFT
EASTWARD INTO THE CENTRAL U.S. THROUGH THE WEEK WITH WARMER THAN
AVERAGE TEMPERATURES UNDERNEATH IT. THE PATTERN IN THE WEST IS
FORECAST TO FLIP TO TROUGHING BY MIDWEEK TO LATE WEEK WITH A COUPLE
ROUNDS OF REINFORCING ENERGY. THIS WILL COOL TEMPERATURES THERE
AND LEAD TO INCREASING PRECIPITATION CHANCES, INCLUDING HIGHER
ELEVATION SNOW.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE ARE IN REASONABLE AGREEMENT REGARDING THE EVOLUTION
OF THE SYNOPTIC PATTERN ACROSS THE EASTERN HALF OF THE COUNTRY
NEXT WEEK. RIDGING IN THE CENTRAL U.S. SLOWLY SHIFTING EAST AND AN
EQUALLY SLOW MOVING EAST COAST TROUGH MOVING INTO THE ATLANTIC ARE
CAPTURED WELL BY THE DETERMINISTIC AND ENSEMBLE GUIDANCE.
THERE'S UNCERTAINTY AROUND A MID-TO-LATE WEEK TROUGH THAT IS
FORECAST TO PROPAGATE FROM THE GULF OF ALASKA INTO THE WESTERN
CONUS. A MORE PROGRESSIVE AND MORE AMPLIFIED WAVE PATTERN IS
DEPICTED BY THE EURO SUITE WHILE THE GFS AND CANADIAN SUITES
SUGGEST THE DEVELOPMENT OF A SPLIT FLOW PATTERN OVER THE WEST WITH
A CUT-OFF LOW OVER THE SOUTHWEST BY LATE NEXT WEEK. THE GFS AND
CANADIAN SUITES HAVE SHOWN SOME RUN-TO-RUN CONSISTENCY FOR THIS
SPLIT FLOW SOLUTION. DESPITE THIS, THE GEFS AND CMCE HAVE MORE
SPREAD IN THEIR SOLUTION THAN THE ECE.
FOR DAYS 3 AND 4, THE BLEND CONSISTS OF THE 06Z GFS AND 00Z
ECMWF/CMC. THE UKMET WAS A BIT TOO AGGRESSIVE WITH A RIDGE AXIS
AND SHORTWAVE ENERGY IN THE WEST ON DAYS 3 AND 4 RESPECTIVELY. A
MORE ENSEMBLE-CENTRIC BLEND IS FAVORED BEGINNING ON DAY 5 AND THE
00Z EC WAS REMOVED FROM THE BLEND BY DAY 6 DUE TO IT'S OUTLIER
SOLUTION REGARDING THE MID-LEVEL PATTERN IN THE WEST/CENTRAL U.S..
..WEATHER/HAZARDS HIGHLIGHTS
BEHIND A SURFACE LOW PRESSURE SYSTEM PULLING NORTH OF NEW ENGLAND
BY TUESDAY AND UNDERNEATH THE UPPER TROUGH CAUSING COOL WESTERLY
FLOW, LAKE-ENHANCED AND TERRAIN-ENHANCED PRECIPITATION IS LIKELY
FROM THE GREAT LAKES REGION INTO THE INTERIOR NORTHEAST AND INTO
THE CENTRAL APPALACHIANS. COLDER TEMPERATURES SHOULD ALLOW FOR SNOW
ESPECIALLY IN THE HIGHER ELEVATIONS. PRECIPITATION SHOULD TAPER
OFF WEDNESDAY, AND THE EAST IS LIKELY TO BE DRY FOR LATER WEEK AS A
COOL SURFACE HIGH SETS UP BEHIND A SECONDARY COLD FRONT. THE
EXCEPTION COULD BE ACROSS SOUTH FLORIDA, WHICH IS FORECAST TO SEE
RETURN FLOW OF MOISTURE BY LATE WEEK FOR INCREASING RAIN AND
THUNDERSTORM CHANCES.
THE DEVELOPING AND RELOADING UPPER TROUGH AND MULTIPLE SURFACE
FRONTS MOVING INTO THE WEST WILL GRADUALLY PUSH PRECIPITATION INTO
THE NORTHERN/CENTRAL WEST COAST BY TUESDAY AND THROUGH THE NORTHERN
ROCKIES INTO WEDNESDAY-THURSDAY. WHILE THERE IS GOOD CONFIDENCE IN
THE OVERALL EVENT, UNRESOLVED SPECIFICS OF THE UPPER TROUGH LEAD
TO GREATER UNCERTAINTY WITH RESPECT TO THE SOUTHWARD/EASTWARD
EXTENT OF PRECIPITATION AS WELL AS MAGNITUDE. EXPECT RELATIVELY
HIGHER TOTALS OVER FAVORED COASTAL AREAS AND THE CASCADES. HIGHER
ELEVATION SNOW IS LIKELY BY MIDWEEK, WHICH MAY BE THE FIRST SNOW OF
THE SEASON IN SOME LOCATIONS GIVEN THE WARM FALL IN THE WEST THUS
FAR. WHILE DETAILS VARY, MODEL GUIDANCE GENERALLY SHOWS
PRECIPITATION SPREADING EAST THROUGH THE INTERIOR WEST/ROCKIES INTO
THURSDAY, AND BY FRIDAY GULF MOISTURE MAY STREAM IN JUST AHEAD OF
THE UPPER TROUGH FOR SOME INCREASING RAIN CHANCES IN THE PLAINS TO
UPPER MIDWEST.
AN UPPER RIDGE ALIGNED OVER THE ROCKIES INTO TUESDAY AND THEN
SHIFTING EASTWARD BY MID AND LATER WEEK WILL PROMOTE WELL ABOVE
NORMAL TEMPERATURES IN ITS VICINITY. THE BIGGEST ANOMALIES ARE
FORECAST ACROSS THE NORTHERN ROCKIES AND HIGH PLAINS TUESDAY-
WEDNESDAY, WHERE HIGHS INTO THE 70S AND 80S ARE 15-25 DEGREES ABOVE
AVERAGE FOR MID-OCTOBER. THESE WARM TEMPERATURES WILL SHIFT INTO
MUCH OF THE PLAINS AND MIDWEST BY THURSDAY-FRIDAY. FOR MUCH OF THE
EASTERN U.S., TEMPERATURES ARE FORECAST TO BE BELOW AVERAGE BY
10-15 DEGREES TUESDAY-WEDNESDAY UNDERNEATH COOL HIGH PRESSURE.
MORNING LOWS MAY CAUSE FROST/FREEZE CONCERNS FROM THE NORTH-CENTRAL
U.S. THROUGH THE MIDWEST/GREAT LAKES AND NORTHEAST/APPALACHIANS.
EXPECT SOME MODERATION THERE BY THURSDAY- SATURDAY. MEANWHILE, THE
UPPER TROUGH AND FRONTAL SURGES COMING INTO THE WEST WILL LEAD TO
BELOW NORMAL TEMPERATURES SPREADING GRADUALLY INLAND FOR THE LATTER
HALF OF THE WEEK. THESE COLDER TEMPERATURES MAY ALSO LEAD TO
ADDITIONAL FROST/FREEZE CONCERNS FOR STILL SUSCEPTIBLE GROWING
AREAS.
KEBEDE/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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page