039
FXUS02 KWBC 022101
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
500 PM EDT WED NOV 02 2022
VALID 12Z SAT NOV 05 2022 - 12Z WED NOV 09 2022
...LINGERING HEAVY RAIN POTENTIAL SATURDAY AFTERNOON/EVENING ALONG
MISSISSIPPI VALLEY SYSTEM/FRONT...
...CHILLY PATTERN OVER THE WEST WITH SIGNIFICANT RAIN/MOUNTAIN
SNOW OVER SOME AREAS...
..OVERVIEW
EXPECT A LEADING MISSISSIPPI VALLEY SYSTEM, AS OF EARLY SATURDAY,
TO EJECT RAPIDLY INTO CANADA BY SATURDAY NIGHT. AS A STRONG UPPER
RIDGE ALONG AND OFFSHORE THE EAST COAST PROVIDES RESISTANCE, A
PORTION OF THE FRONT TRAILING FROM THE SURFACE LOW TO STALL AND
EVENTUALLY LIFT NORTHWEST AS A WARM FRONT BEFORE DISSIPATING.
GUIDANCE SUGGESTS THAT THE AXIS OF AN AMPLIFIED MEAN TROUGH WILL
SETTLE NEAR THE WEST COAST, BUT WITH SOME UNCERTAINTY OVER THE
AMPLITUDE OF THIS TROUGH/PROGRESSION OF EJECTING ENERGY DUE TO
DIFFERENCES IN THE DEPICTION OF A STRONG UPPER RIDGE THAT BUILDS
OVER ALASKA AND VICINITY. AT THE VERY LEAST THIS PATTERN SHOULD
SUPPORT SEVERAL DAYS OF BELOW NORMAL TEMPERATURES ACROSS THE WEST
AND MULTIPLE EPISODES OF RAIN AND MOUNTAIN SNOW FROM THE WEST
COAST INTO THE ROCKIES. A SYSTEM EMERGING FROM THE WEST COULD
ALSO PRODUCE MEANINGFUL PRECIPITATION ACROSS PARTS OF THE NORTHERN
TIER DURING THE FIRST HALF OF NEXT WEEK.
..GUIDANCE AND PREDICTABILITY ASSESSMENT
THE DETERMINISTIC AND ENSEMBLE MEANS HAVE TRENDED FASTER WITH THE
OVERALL SYNOPTIC FLOW OVER THE LOWER 48 DURING THE MEDIUM RANGE
PERIOD.
THE 00Z EC/UK/CMC AND 06Z GFS TENDED TO HANDLE THE SOUTHERN U.S.
TROUGH AND EASTERN FAIRLY WELL ON DAY 3. THE EMERGENCE OF THE
AMPLIFYING EASTERN PACIFIC TROUGH PROVIDES MORE OF A CHALLENGE TO
THE AVAILABLE GUIDANCE BEYOND DAY 3. THE 00Z ECE WAS INTRODUCED
WHILE THE 00Z UK WAS DIMINISHED ON DAY 4 DUE TO DIFFERENCES WITH
RESPECT TO THE APPROACHING PACIFIC TROUGH. THERE'S A REASONABLE
CONSENSUS ON THE ORIENTATION OF THE EASTERN CONUS RIDGE THROUGHOUT
THE MEDIUM RANGE, BUT UNCERTAINTY ARISES WITH THE ARRIVAL OF THE
UPPER LOW OVER THE EASTERN PACIFIC. A BLEND CONSISTING OF THE 00Z
EC/UK/CMC/GEFS/ECE AND 06Z GFS WERE USED ON DAY 5 TO FIND SOME
SORT OF MIDDLE GROUND SOLUTION WITH RESPECT TO THE TIMING AND
INTENSITY OF THIS PAC NW SYSTEM. THE UKMET IS DROPPED BY DAY 6 AND
BY DAY 7 WE'RE LEFT WITH THE 00Z ECE/CMCE/GEFS.
..WEATHER/HAZARD HIGHLIGHTS
THE LEADING SYSTEM TRACKING NORTHEASTWARD FROM THE MISSISSIPPI
VALLEY ON SATURDAY, ALONG WITH ITS ASSOCIATED FRONTS, WILL PRODUCE
SOME LOCALLY MODERATE TO HEAVY RAINFALL BUT LIKELY WITH LOWER
TOTALS THAN EXPECTED DURING FRIDAY-FRIDAY NIGHT. AREAS OF INTEREST
FOR ENHANCED RAINFALL WILL BE OVER THE UPPER MIDWEST/UPPER GREAT
LAKES NEAR THE SURFACE LOW TRACK AS WELL AS OVER/NEAR THE LOWER
MISSISSIPPI VALLEY AS THE TRAILING FRONT DECELERATES.
AREAS FROM THE WEST COAST INTO THE NORTHERN HALF OF THE ROCKIES
SHOULD SEE MULTIPLE EPISODES OF RAIN AND HIGHER ELEVATION SNOW,
WITH SNOW LEVELS TENDING TO DECLINE WITH TIME AS THE MEAN TROUGH
ALOFT NEAR THE WEST COAST AMPLIFIES. UNCERTAINTY OVER THE PRECISE
AMPLITUDE OF THE TROUGH LOWERS CONFIDENCE IN THE PRECISE FOCUS OF
HIGHEST TOTALS, BUT THE BEST SIGNAL AT THE MOMENT IS GENERALLY
OVER SOUTHERN OREGON AND NORTHERN CALIFORNIA. MULTIPLE SYSTEMS MAY
PROVIDE ADDED FOCUS. THESE INCLUDE A FRONT REACHING THE NORTHWEST
BY SATURDAY AND A SYSTEM APPROACHING THE NORTHWEST ON SUNDAY. ANY
POTENTIAL SYSTEMS NEXT WEEK HAVE LOWER CONFIDENCE. THIS LOWER
CONFIDENCE EXTENDS TO ANY LOW PRESSURE THAT MAY EXTEND INTO THE
PLAINS WITH AN AREA OF SNOW OR RAIN DEPENDING ON TRACK/EVOLUTION.
MOISTURE SHOULD EVENTUALLY INCREASE NEAR THE EAST COAST NEXT WEEK
AS THE UPPER LOW INITIALLY OVER THE EASTERN BAHAMAS RETROGRADES
TOWARD THE SOUTHEASTERN U.S./FLORIDA.
AFTER A BRIEF REBOUND TO ONLY MODERATELY BELOW NORMAL TEMPERATURES
OVER THE WEST DURING THE WEEKEND, THE FORECAST OF AN AMPLIFYING
UPPER TROUGH NEXT WEEK SHOULD EXPAND THE COVERAGE OF HIGHS 10-20F
BELOW NORMAL ACROSS THE WEST ONCE AGAIN. COLDEST AIR SHOULD EXTEND
FROM WESTERN CANADA INTO MONTANA WITH SOME HIGHS IN THAT STATE
20-35F BELOW NORMAL MONDAY-WEDNESDAY. IN CONTRAST TO THE SOMEWHAT
WINTER-LIKE TEMPERATURES OVER THE WEST, THE EAST WILL SEE
TEMPERATURES MORE TYPICAL FOR EARLIER IN THE FALL WITH A BROAD
AREA OF PLUS 10-25F ANOMALIES, ESPECIALLY SATURDAY-MONDAY WHEN
DAILY RECORDS SHOULD BE MOST NUMEROUS. ANOMALIES SHOULD BE A
LITTLE MORE EXTREME FOR MORNING LOWS VERSUS DAYTIME HIGHS. PLUS
10-20F READINGS SHOULD BE MORE COMMON BY TUESDAY-WEDNESDAY.
KEBEDE/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.PHP
HAZARDS:
- HEAVY PRECIPITATION ACROSS PORTIONS OF CALIFORNIA, THE PACIFIC
NORTHWEST, AND THE NORTHERN GREAT
BASIN, SAT-MON, NOV 5-NOV 7.
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE CENTRAL GREAT BASIN,
CALIFORNIA, AND THE SOUTHWEST,
SUN-TUE, NOV 6-NOV 8.
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE NORTHERN PLAINS, THE
NORTHERN ROCKIES, ANDTHE CENTRAL
ROCKIES, SAT-SUN, NOV 5-NOV 6.
- HEAVY RAIN ACROSS PORTIONS OF CALIFORNIA AND THE PACIFIC
NORTHWEST, SAT-SUN, NOV 5-NOV 6.
- HEAVY RAIN ACROSS PORTIONS OF THE LOWER MISSISSIPPI VALLEY, AND
THE TENNESSEE VALLEY, SAT, NOV 5.
- HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN PLAINS AND THE
NORTHERN ROCKIES, MON, NOV 7.
- HIGH WINDS ACROSS PORTIONS OF THE NORTHERN/CENTRAL ROCKIES AND
THE NORTHERN/CENTRAL PLAINS, SAT,
NOV 5.
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,
QUANTITATIVE PRECIPITATION, EXPERIMENTAL EXCESSIVE RAINFALL
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES AND HEAT INDICES 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
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