766
FXUS02 KWBC 021900
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 PM EDT SAT NOV 2 2024
VALID 12Z TUE NOV 05 2024 - 12Z SAT NOV 09 2024
..OVERVIEW
THE MAJORITY OF GUIDANCE SHOWS STRONG UPPER RIDGING OVER PARTS OF
THE SOUTHEASTERN U.S. AND WESTERN ATLANTIC WHILE STRONGLY DIGGING
WESTERN U.S. TROUGH ENERGY LIKELY CLOSES OFF A LOW THAT DRIFTS OVER
THE FOUR CORNERS BEFORE EMERGING INTO THE PLAINS BY LATE WEEK OR
EARLY WEEKEND. THE UPPER LOW SHOULD PRODUCE AN AREA OF POTENTIALLY
SIGNIFICANT SNOWFALL OVER PARTS OF THE ROCKIES AROUND MIDWEEK AND
THEN SPREAD RAIN OVER THE PLAINS LATER IN THE WEEK. TO THE SOUTH OF
THE UPPER RIDGE, GUIDANCE CONTINUES TO SHOW POSSIBLE CARIBBEAN INTO
GULF OF MEXICO TROPICAL DEVELOPMENT (BEING MONITORED BY THE
NATIONAL HURRICANE CENTER) WITH A LOT OF GUIDANCE SPREAD FOR WHERE
THE SURFACE SYSTEM ITSELF MAY TRACK, AS WELL AS FOR THE PATH OF
MOISTURE TO ITS NORTH/EAST. A WAVY FRONT PUSHING INTO THE
MISSISSIPPI VALLEY BY TUESDAY MAY PRODUCE SOME ENHANCED RAINFALL
OVER THAT REGION. NORTHERN STREAM FLOW WILL SEE MODERATE
PROGRESSION, WITH A RIDGE BUILDING INTO WESTERN CANADA AND MEAN
TROUGHING SETTING UP FARTHER EAST. A PACIFIC TROUGH MAY APPROACH
THE NORTHWEST BY NEXT SATURDAY.
..GUIDANCE/PREDICTABILITY ASSESSMENT
UPDATED 00Z/06Z GUIDANCE IS IN GOOD AGREEMENT DURING THE EARLY PART
OF THE MEDIUM-RANGE PERIOD (TUESDAY NOV 5 - SATURDAY NOV 9),
DEPICTING A LEAD SOUTHERN STREAM WAVE LIFTING NORTHWARD AHEAD OF A
BROAD AREA OF HIGH PRESSURE OVER THE EAST COAST WHILE MEAN
TROUGHING REMAINS OVER THE WEST IN AN AMPLIFIED PATTERN. THIS WILL
LEAD TO A WEAKENING WAVY FRONTAL BOUNDARY THROUGH THE
MIDWEST/MISSISSIPPI VALLEY AS THE LEAD ENERGY LIFTS NORTHWARD AHEAD
OF ADDITIONAL ENERGIES FROM THE WEST. GUIDANCE DIFFERS ON THE
TIMING OF NORTHERN STREAM SHORTWAVES AND ACCOMPANYING FRONTAL
SYSTEMS IN THE MID- TO LATE PERIOD ALONG THE NORTHERN TIER OF THE
COUNTRY, THOUGH WITH LITTLE APPARENT IMPACTS ON SENSIBLE WEATHER.
ATTENTION TURNS WEST AS A SHORTWAVE HELPS REINFORCE MEAN TROUGHING,
WITH ALL THE DETERMINISTIC GUIDANCE AND GEFS/ECENS MEANS DEPICTING
THE DEVELOPMENT OF A CLOSED LOW OVER THE SOUTHWEST. EASTWARD
PROGRESSION OF THE LOW IS FASTEST IN THE UKMET FOLLOWED BY THE GFS.
THE ECMWF IS THE SLOWEST WITH THE CMC MOST SIMILAR. THE ECENS MEAN
AND GEFS MEAN GENERALLY FOLLOW THEIR RESPECTIVE DETERMINISTIC
COUNTERPARTS. THE EC AI SUITE OF MODELS SHOW VARIOUS SOLUTIONS
WITHIN THE RANGE OF GUIDANCE, INDICATING INCREASING UNCERTAINTY
DURING THIS TIMEFRAME. THE 12Z GFS CAME IN AHEAD OF THE ECMWF/CMC
SIMILAR TO THE 06Z RUN.
EYES WILL ALSO BE ON THE TROPICS AS THE NATIONAL HURRICANE CENTER
MONITORS A SYSTEM IN THE SOUTHWESTERN CARIBBEAN, CURRENTLY
INDICATING AN 80% CHANCE OF TROPICAL SYSTEM FORMATION IN THE NEXT 7
DAYS. THE GFS/ECMWF AS WELL AS THE ENSEMBLE MEANS INDICATE AN AREA
OF LOW PRESSURE LIFTING NORTHWARD TOWARDS THE EASTERN GULF OF
MEXICO BEFORE TAKING VARIOUS PATHS FURTHER NORTH OR WEST, WITH THE
GFS FURTHER TO THE NORTH AND INTO THE CENTRAL GULF AND THE ECMWF
TO THE WEST. THE GFS PATH IS FURTHER EAST COMPARED TO PRIOR RUNS.
THE CMC HAS BEEN AN OUTLIER WITH A MUCH FASTER, EASTERN PATH
THROUGH THE GULF AND INTO THE SOUTHEASTERN U.S. THE UPDATED NHC/WPC
COORDINATED FORECAST BRINGS AN AREA OF LOW PRESSURE INTO THE GULF
JUST TO THE WEST OF THE GFS PATH, SHOWING A MORE EASTWARD TREND
THAN THE PRIOR FORECAST BUT STILL INCORPORATING THE POTENTIAL FOR
MORE WESTWARD MOVEMENT AS INDICATED BY THE ECMWF.
THE UPDATED WPC FORECAST USES A COMPOSITE BLEND OF THE
DETERMINISTIC GUIDANCE WITH GOOD OVERALL AGREEMENT IN THE EARLY
PERIOD. THE UKMET IS REMOVED IN THE MID-PERIOD GIVEN ITS MUCH
FASTER PROGRESSION OF THE SOUTHWESTERN CLOSED LOW, AND THE CMC IS
REMOVED GIVEN THE MORE AGGRESSIVE NORTHEASTWARD TRACK OF THE
CARIBBEAN LOW PRESSURE SYSTEM. THE ECMWF IS EMPHASIZED OVER THE GFS
FOR THE END OF THE PERIOD FAVORING MORE DETAIL OF THE WESTERN
POSITION OF THE CLOSED LOW GIVEN SOME AGREEMENT FROM THE CMC IN
THIS AREA, WITH A CONTRIBUTION FROM BOTH THE GEFS/ECENS MEANS TO
HELP ACCOUNT FOR THE INCREASING UNCERTAINTY.
THE QPF FORECAST REMAINS MORE DIFFICULT, WITH NOTABLY HIGH
UNCERTAINTY FOR POTENTIAL RAINFALL OVER FLORIDA AND THE
SOUTHEASTERN U.S. WITH INCREASING MOISTURE AHEAD OF THE APPROACHING
LOW, INCLUDING HIGH SPATIAL DISPARITY WITH THE ENSEMBLE MEANS.
FAVORED THE NBM WHICH INDICATES HIGHER RAINFALL OVER CENTRAL/SOUTH
FLORIDA THOUGH MODERATED BY THE MEANS GIVEN HIGH UNCERTAINTY.
LATER IN THE FORECAST TOWARD THE END OF THE WEEK, HIGHER RAINFALL
AMOUNTS ARE INDICATED WITH MORE MODERATE SPATIAL DIFFERENCES LATER
THURSDAY/EARLY FRIDAY AS THE CLOSED LOW OVER THE SOUTHWEST BEGINS
TO EMERGE OVER THE PLAINS. SPATIAL DIFFERENCES INCREASE ONCE AGAIN
LATER FRIDAY/EARLY SATURDAY WITH THE GFS FAVORING A FASTER
NORTHEASTWARD PROGRESSION TOWARDS THE MIDWEST WHILE THE ECMWF
FAVORS AREAS FURTHER WEST OVER THE PLAINS. THE DETERMINISTIC
GUIDANCE WAS USED MORE TO INCREASE TOTALS GIVEN THE SIGNAL FOR
HEAVIER PRECIPITATION BEFORE REVERTING TO HIGHER CONTRIBUTIONS FROM
THE MEANS ONCE AGAIN GIVEN SPATIAL DISPARITY.
..WEATHER/HAZARDS HIGHLIGHTS
A SLOW WAVY FRONT SHOULD APPROACH/REACH THE MISSISSIPPI VALLEY AND
WESTERN GULF COAST BY TUESDAY-TUESDAY NIGHT, WITH CONTINUED
POTENTIAL FOR SOME TRAINING OF MODERATE TO HEAVY RAINFALL BUT
LIKELY TO A LESS PRONOUNCED DEGREE THAN EXPECTED JUST TO THE WEST
IN THE SHORT RANGE. THE DAY 4 EXCESSIVE RAINFALL OUTLOOK MAINTAINS
A MARGINAL RISK AREA FROM THE LOWER OHIO VALLEY SOUTHWESTWARD, NOW
EXTENDING TO THE NORTHERN HALF OF THE TEXAS COAST. THERE HAS BEEN
SOME IMPROVEMENT FOR GUIDANCE CLUSTERING REGARDING WHERE THE
RELATIVE MAXIMUM OF RAINFALL SHOULD BE WITHIN THIS REGION (ALONG
AND JUST EAST OF AN AREA FROM EASTERN ARKANSAS INTO FAR SOUTHERN
ILLINOIS). HOWEVER GROUND CONDITIONS ARE GENERALLY NEUTRAL TO DRY
AND THE GFS/ECMWF DO NOT SUGGEST TOO MUCH INSTABILITY REACHING THAT
FAR NORTH. THUS FOR NOW WILL MAINTAIN JUST THE MARGINAL RISK AREA
WHILE MONITORING FOR SIGNALS OF ANY HEAVIER BANDS THAT COULD FAVOR
AN UPGRADE.
ESPECIALLY BY WEDNESDAY, GUIDANCE DIVERGES CONSIDERABLY REGARDING
THE DETAILS OF ANOMALOUS MOISTURE/HEAVIER RAINFALL THAT MAY
OVERSPREAD PARTS OF THE SOUTHEAST/FLORIDA TO THE NORTH OF THE
POSSIBLE CARIBBEAN INTO GULF TROPICAL DEVELOPMENT. THIS WILL DEPEND
ON FINER SCALE DETAILS OF UPPER RIDGING WHOSE WESTERN SIDE WILL
DETERMINE HOW MUCH MOISTURE/SHORTWAVE ENERGY MAY LIFT NORTHWARD.
THE MOST COMMON THEME IS FOR SIGNIFICANT PRECIPITABLE WATER
ANOMALIES TO REACH PORTIONS OF THE FLORIDA PENINSULA AT THE VERY
LEAST, SO THE DAY 5 ERO STARTS OUT WITH A MARGINAL RISK AREA OVER
THE SOUTHERN TWO-THIRDS OF FLORIDA. OTHER PARTS OF THE SOUTHEAST
MAY ULTIMATELY BE INCLUDED DEPENDING ON GUIDANCE TRENDS. GUIDANCE
SPREAD FOR WHAT HAPPENS WITH THIS MOISTURE AND THE POSSIBLE GULF
FEATURE AFTER THURSDAY IS STILL VERY WIDE, KEEPING CONFIDENCE LOW.
UPPER TROUGH DYNAMICS LIKELY CLOSING OFF AN UPPER LOW AROUND THE
FOUR CORNERS SHOULD PUSH AN AREA OF MOUNTAIN SNOW SOUTHWARD
THROUGH THE ROCKIES, WITH HIGHEST TOTALS LIKELY TO BE OVER SOUTHERN
COLORADO/NORTHERN NEW MEXICO BASED ON THE CURRENT FORECAST PATH OF
THE UPPER LOW. GUIDANCE TRENDS HAVE INDICATED MORE CONFIDENCE THAT
SOME SNOW COULD ALSO OCCUR OVER PORTIONS OF THE HIGH PLAINS.
EXPECT RAINFALL OVER THE PLAINS TO INCREASE IN COVERAGE AND
INTENSITY AFTER MIDWEEK AS THE FOUR CORNERS UPPER LOW BEGINS TO
DRIFT EASTWARD. THERE IS STILL UNCERTAINTY FOR THE DETAILS, BUT
GRADUALLY INCREASING CONFIDENCE IN SOME AREAS OF HEAVIER RAINFALL.
A LARGE PORTION OF THE EASTERN U.S. WILL SEE WELL ABOVE NORMAL
TEMPERATURES, ESPECIALLY FROM TUESDAY INTO THURSDAY MORNING WHEN
SOME AREAS WILL SEE PLUS 20F OR GREATER ANOMALIES (MORE FOR MORNING
LOWS VERSUS DAYTIME HIGHS) ALONG WITH POTENTIAL FOR DAILY RECORDS
FOR HIGHS/WARM LOWS. FRONTAL PROGRESSION WILL TEMPER THE MOST
EXTREME ANOMALIES BUT PERSISTENT SOUTHEAST UPPER RIDGING SHOULD
KEEP THE SOUTHERN TWO-THIRDS OF THE EAST ABOVE NORMAL THROUGH
FRIDAY-SATURDAY. IN CONTRAST, THE UPPER TROUGH/LOW LIKELY AFFECTING
THE WEST/ROCKIES FOR MULTIPLE DAYS SHOULD PRODUCE CHILLY
TEMPERATURES FOR MOST OF NEXT WEEK WITH HIGHS OF 10-20F BELOW
NORMAL MOST COMMON WEDNESDAY-FRIDAY.
PUTNAM/RAUSCH
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.PHPSCHICHTEL/HAMRICK
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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