762
FXUS02 KWBC 312021
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
420 PM EDT MON OCT 31 2022
VALID 12Z THU NOV 03 2022 - 12Z MON NOV 07 2022
...WESTERN-CENTRAL U.S. SYSTEM TO BRING HEAVY MOUNTAIN SNOW TO
PARTS OF THE GREAT BASIN/ROCKIES AND HEAVY RAIN POTENTIAL TO
PORTIONS OF THE PLAINS...
...LATE WEEK ATMOSPHERIC RIVER EVENT LIKELY TO BRING AN EPISODE OF
HEAVY PRECIPITATION TO PARTS OF THE NORTHWEST...
..OVERVIEW
EXPECT AN AMPLIFIED PATTERN TO PREVAIL DURING LATE THIS WEEK INTO
THE EARLY WEEKEND AS A DEEP TROUGH CARRIES AN EMBEDDED UPPER LOW
ACROSS SOUTHERN PARTS OF THE WEST AND STRONG RIDGING BUILDS OVER
THE EAST. MEANWHILE STRONG NORTH PACIFIC FLOW WILL INITIALLY
EXTEND INTO SOUTHWESTERN CANADA AND THEN SAG SOUTHWARD INTO THE
NORTHWEST U.S. ONCE THIS PACIFIC JET REACHES FAR ENOUGH SOUTH
AFTER EARLY SATURDAY, IT SHOULD ACCELERATE THE UPPER LOW
PROGRESSING EASTWARD/NORTHEASTWARD ACROSS AND BEYOND THE PLAINS.
BY LATE WEEKEND INTO EARLY NEXT WEEK THE PATTERN SHOULD TAKE ON A
MORE ZONAL OR BROADLY CYCLONIC LOOK AS EAST-WEST TROUGHING EVOLVES
OVER THE WESTERN HALF OF CANADA IN RESPONSE TO STRONG ALASKA
RIDGING WHILE THE EAST COAST RIDGE MOVES INTO THE ATLANTIC. THE
LEADING WESTERN SYSTEM WILL INITIALLY SUPPORT MEANINGFUL
RAIN/MOUNTAIN SNOW OVER PARTS OF THE FOUR CORNERS STATES AND THEN
A HEAVY RAIN THREAT SHOULD EMERGE OVER THE SOUTH-CENTRAL PLAINS,
WHILE THE NORTHWEST ATMOSPHERIC RIVER EVENT SHOULD BE MOST
PRONOUNCED AROUND FRIDAY-FRIDAY NIGHT WITH A GRADUALLY LIGHTER
TREND THEREAFTER.
..GUIDANCE AND PREDICTABILITY ASSESSMENT
THE LATEST GUIDANCE SHOWS GOOD ENOUGH AGREEMENT DAYS 3 AND 4 FOR A
PURELY DETERMINISTIC MODEL BLEND. TIMING AND INTENSITY DIFFERENCES
REALLY START TO EMERGE BY DAY 5/SATURDAY REGARDING THE CLOSED LOW
AS IT LIFTS FROM THE SOUTHERN PLAINS INTO THE MIDWEST AND
EVENTUALLY THE UPPER GREAT LAKES, WITH SOME NOTABLE SHIFTS IN THE
GUIDANCE WITH THE NEW 12Z GUIDANCE (WHICH WAS AVAILABLE AFTER
FORECAST GENERATION TIME). THE 00Z ECMWF WAS THE QUICKEST TO LIFT
THE LOW OUT OF THE SOUTHERN PLAINS AFTER SATURDAY AND PHASE IT
WITH A NORTHERN STREAM SHORTWAVE ACROSS THE NORTHERN PLAINS, AND
THE NEW 12Z RUN MAINTAINS THAT (ALTHOUGH IS EVEN QUICKER TO WEAKEN
THE LOW OVER THE MIDWEST). THE GFS ON THE OTHER HAND IS SLOWER AND
MUCH MORE AMPLIFIED THAN THE ECMWF, MAINTAINING AND WELL DEFINED
CLOSED LOW OVER THE MIDWEST THROUGH SUNDAY. THE 12Z MAINTAINS THIS
STRONGER DEPICTION, BUT IS A LITTLE FASTER THAN ITS 6Z RUN (THOUGH
STILL SLOWER THAN THE ECMWF). THE CMC WAS ALSO STRONGER THAN THE
GFS AND BOTH ITS 00Z AND 12Z RUNS FROM TODAY ARE PRETTY CLOSE TO
THE NEW 12Z RUN FROM THE GFS. THE ENSEMBLE MEANS WERE OF COURSE
WEAKER THAN THE DETERMINISTIC RUNS, BUT AT LEAST KEPT A FAIRLY
MIDDLE GROUND ON PLACEMENT. WITHOUT A CLEAR DIRECTION, THE WPC
FORECAST OPTED TO LEAN CLOSER TO CONTINUITY WHICH FAVORED
SOMETHING MORE LIKE THE GFS. FOR DAYS 6 AND ESPECIALLY 7, BLENDING
THE MEANS WITH CONTINUITY AND THE 06Z GFS SEEMED TO GIVE A
REASONABLE SOLUTION FOR NOW. IT DOES APPEAR GIVEN THE LATEST
TRENDS IN THE 12Z GUIDANCE, THERE IS SUPPORT FOR A LITTLE BIT
FASTER PROGRESSION OF THIS SYSTEM THAN EVEN THE CURRENT WPC
FORECAST DEPICTS, BUT THESE TRENDS WILL NEED TO BE MONITORED TO
SEE IF THEY CONTINUE IN SUBSEQUENT CYCLES. THE DETAILS AND
PREDICTABILITY OF ENERGY INTO THE PACIFIC NORTHWEST SEEMED TO
DECLINE APPRECIABLY BY DAYS 6 AND 7 AND SO A TREND TOWARDS THE
ENSEMBLE MEANS WAS FAVORABLE THERE AS WELL.
..WEATHER/HAZARD HIGHLIGHTS
THE INITIAL WESTERN U.S. UPPER TROUGH AND EMBEDDED LOW TRACKING
ACROSS SOUTHERN PARTS OF THE WEST WILL INITIALLY BRING MOUNTAIN
SNOW AND LOWER ELEVATION RAIN TO THE GREAT BASIN AND CENTRAL
ROCKIES, WITH SOME PRECIPITATION EXTENDING FARTHER SOUTH AS WELL.
WPC WINTER WEATHER OUTLOOK PROBABILITIES REFLECT AREAS WITH THE
BEST POTENTIAL FOR MEANINGFUL TO HEAVY MOUNTAIN SNOW OVER THIS
REGION. EXPECT RAIN TO INCREASE IN COVERAGE AND INTENSITY OVER THE
CENTRAL U.S. LATE IN THE WEEK AND PERSIST INTO THE WEEKEND AS THE
WESTERN SYSTEM APPROACHES. SOME RAIN MAY BECOME HEAVY AND STRONG
CONVECTION IS POSSIBLE AS WELL, AS PER THE LATEST OUTLOOKS FROM
THE STORM PREDICTION CENTER. THE EXPERIMENTAL DAY 5 EXCESSIVE
RAINFALL OUTLOOK CURRENTLY DEPICTS A SLIGHT RISK AREA FROM
PORTIONS OF EASTERN KANSAS INTO NORTHERN TEXAS FOR THE EARLY
FRIDAY INTO EARLY SATURDAY TIME FRAME. THIS EVENT MAY FEATURE A
COMBINATION OF FLASH FLOOD THREATS (IN MAINLY URBANIZED/METRO
REGIONS) WHERE THE HEAVIEST RAIN OCCURS BUT ALSO BENEFICIAL
RAINFALL GIVEN THE LONG-TERM DROUGHT OVER THE REGION. MONITOR
STORM PREDICTION CENTER OUTLOOKS FOR LATEST INFORMATION ON SEVERE
POTENTIAL. RAINFALL SHOULD TREND LIGHTER AND MORE PROGRESSIVE FROM
LATE WEEKEND INTO EARLY NEXT WEEK AS THE SUPPORTING UPPER LOW
ACCELERATES NORTHEASTWARD.
THE OTHER SIGNIFICANT PRECIPITATION FOCUS WILL BE OVER THE
NORTHWEST LATE THIS WEEK INTO THE WEEKEND, DUE TO AN ATMOSPHERIC
RIVER EVENT ASSOCIATED WITH STRONG WESTERLY FLOW REACHING INTO THE
REGION. A PERIOD OF HEAVY RAIN/MOUNTAIN SNOW APPEARS LIKELY WITH
HIGHEST TOTALS TENDING TO BE DURING FRIDAY-FRIDAY NIGHT. SOME
SIGNIFICANT PRECIPITATION SHOULD CONTINUE INTO THE WEEKEND BUT THE
SOUTHWARD PROGRESSION OF THE PACIFIC JET (LIKEWISE PUSHING THE
PRECIPITATION SHIELD GRADUALLY FARTHER SOUTH) SHOULD BE SUFFICIENT
TO ALLOW FOR A LIGHTER TREND. A PERIOD OF STRONG WINDS WILL BE
POSSIBLE IN THIS EVENT AS WELL. SOMEWHAT LESS EXTREME BUT STILL
SIGNIFICANT PRECIPITATION WILL REACH INTO THE NORTHERN ROCKIES.
THE WEST WILL SEE A BROAD AREA OF DAYTIME HIGHS 10-20F OR SO BELOW
NORMAL UNDER THE FORECAST UPPER TROUGH/LOW THROUGH FRIDAY. SOME
AREAS OVER OR NEAR SOUTHERN CALIFORNIA MAY SEE RECORD COLD HIGHS.
DOUBLE-DIGIT ANOMALIES SHOULD BECOME MUCH MORE SCATTERED DURING
THE WEEKEND AS TEMPERATURES MODERATE BUT MOST AREAS SHOULD REMAIN
NEAR TO BELOW NORMAL FOR HIGHS. THE EVOLVING UPPER PATTERN SHOULD
SUPPORT A PUSH OF COLD AIR REACHING THE NORTHERN HIGH
PLAINS/EASTERN SLOPES OF THE ROCKIES BY NEXT MONDAY, POSSIBLY
BRINGING HIGHS DOWN TO 20-30F BELOW NORMAL OVER MONTANA. ON THE
OTHER HAND, WELL ABOVE NORMAL TEMPERATURES WILL PREVAIL OVER MOST
AREAS EAST OF THE ROCKIES THROUGH ABOUT THURSDAY AND THEN THE
PLAINS WILL LIKELY TREND COOLER WHILE THE MISSISSIPPI VALLEY AND
ESPECIALLY THE EAST REMAIN WARM. DURING THURSDAY-EARLY FRIDAY THE
WARMEST ANOMALIES (PLUS 10-25F) SHOULD BE FROM THE UPPER MIDWEST
INTO CENTRAL PLAINS WHILE AREAS FROM THE GREAT LAKES/OHIO VALLEY
INTO NORTHEAST SHOULD SEE MULTIPLE DAYS WITH TEMPERATURES 10-20F
ABOVE NORMAL DURING THE PERIOD.
SANTORELLI/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, FRI-SUN, NOV 4-NOV 6.
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE NORTHERN ROCKIES AND
THE NORTHERN GREAT BASIN,
SAT-SUN, NOV 5-NOV 6.
- HEAVY RAIN ACROSS PORTIONS OF THE CENTRAL PLAINS, THE MIDDLE
MISSISSIPPI VALLEY, THE LOWER
MISSISSIPPI VALLEY, THE SOUTHERN PLAINS, AND THE UPPER MISSISSIPPI
VALLEY, FRI-SAT, NOV 4-NOV 5.
- SEVERE WEATHER ACROSS PORTIONS OF THE CENTRAL PLAINS AND THE
SOUTHERN PLAINS, THU, NOV 3.
- SEVERE WEATHER ACROSS PORTIONS OF THE SOUTHERN PLAINS, FRI, NOV
4.
- FLOODING OCCURRING OR IMMINENT ACROSS PORTIONS OF THE SOUTHEAST.
- HIGH WINDS ACROSS PORTIONS OF THE NORTHERN PLAINS AND THE
NORTHERN ROCKIES, FRI-SAT, NOV 4-NOV 5.
- HIGH WINDS ACROSS PORTIONS OF MAINLAND ALASKA, THU-SAT, NOV
3-NOV 5.
- HIGH WINDS ACROSS PORTIONS OF THE ALASKA PANHANDLE, FRI-MON, NOV
4-NOV 7.
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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