365
FXUS02 KWBC 120700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT WED OCT 12 2022
VALID 12Z SAT OCT 15 2022 - 12Z WED OCT 19 2022
..PATTERN OVERVIEW
A MORE ACTIVE FALL WEATHER PATTERN IS EXPECTED TO REMAIN IN PLACE
THROUGH THE UPCOMING WEEKEND AND BEYOND AS A COUPLE OF COLD FRONTS
ASSOCIATED WITH AN EASTERN U.S. AMPLIFYING UPPER LEVEL TROUGH (AND
EMBEDDED SHORTWAVES) MOVE ACROSS THE CENTRAL AND EASTERN STATES.
THE FIRST COLD FRONT WILL HAVE EXITED THE EAST COAST BEFORE
SATURDAY WITH RAIN EXITING EASTERN NEW ENGLAND, AND LAKE EFFECT
PRECIPITATION BEHIND IT. BY SUNDAY AND INTO MONDAY, A SECOND COLD
FRONT DROPPING SOUTHWARD FROM CANADA IS EXPECTED TO REINFORCE THE
COOL AIRMASS ACROSS THE EASTERN HALF OF THE NATION AND WILL LAST
INTO EARLY NEXT WEEK. THE OPPOSITE IS EXPECTED TO BE THE CASE
ACROSS THE WEST COAST REGION AS AN UPPER RIDGE BRINGS A PERIOD OF
WELL ABOVE NORMAL TEMPERATURES FROM CALIFORNIA TO THE PACIFIC
NORTHWEST AS SUMMER TRIES TO HANG ON A LITTLE LONGER.
..MODEL AND PREDICTABILITY ASSESSMENT
THE SYNOPTIC SCALE PATTERN HAS VERY GOOD OVERALL AGREEMENT AND
THIS ALSO HOLDS TRUE FOR RUN-TO-RUN MODEL CONSISTENCY OVER THE
PAST FEW RUNS. THE MAIN MODEL DIFFERENCES THROUGH MONDAY RESIDE
ACROSS ONTARIO AND THE NORTHERN GREAT LAKES WITH THE OVERALL
ORIENTATION OF THE MAIN UPPER LOW, BUT THE BROAD CYCLONIC FLOW
PATTERN IS IN EXCELLENT AGREEMENT. THE MODELS ARE ALSO HINTING AT
ANOTHER POTENTIAL CLOSED LOW DEVELOPING OFF THE CALIFORNIA COAST
BY NEXT WEDNESDAY.
GIVEN THE LOWER PREDICTABILITY ELEMENTS WITHIN THE MORE CONFIDENT
MEAN PATTERN, THE UPDATED FORECAST STARTED WITH AN OPERATIONAL
MODEL COMPOSITE FOR ABOUT THE FIRST HALF OF THE PERIOD AND
TRANSITIONED TO A MODEL/MEAN BLEND THEREAFTER. IN TERMS OF QPF,
AMOUNTS WERE RAISED FROM THE NBM ACROSS THE GREAT LAKES TO BETTER
ACCOUNT FOR LAKE EFFECT PRECIP AND INCREASED LIGHT AMOUNTS IN
OTHER PARTS OF THE EAST-CENTRAL U.S. TO ACCOUNT FOR THE TYPICALLY
LOW NBM BIAS FOR SUCH AMOUNTS AND INTERMEDIATE FRONTAL TIMING.
..SENSIBLE WEATHER AND POTENTIAL HAZARDS
PERIODS OF LAKE ENHANCED RAIN AND SNOW SHOWERS ARE LIKELY ACROSS
THE GREAT LAKES FOR THE FRIDAY THROUGH SATURDAY TIME PERIOD.
SHOWERS COULD BECOME MORE WIDESPREAD SUNDAY INTO NEXT WEEK WITH
ANOTHER FRONTAL SYSTEM AND TRAILING COLD CYCLONIC LOW LEVEL FLOW.
TIMING DIFFERENCES IN THE GUIDANCE FOR THIS LATTER FRONT KEEP
CONFIDENCE MORE IN CHECK FOR RAINFALL AMOUNTS/COVERAGE OVER THE
EASTERN U.S. EARLY NEXT WEEK. MEANWHILE SHOWERS AND THUNDERSTORMS
ARE FORECAST TO INCREASE IN COVERAGE OVER ARIZONA AND NEW MEXICO
BY SATURDAY, AND THEN INTO TEXAS FROM SUNDAY INTO EARLY NEXT WORK
WEEK, AS THE UPPER LOW TRACKING INTO THE REGION FROM THE PACIFIC
ADVECTS COPIOUS MOISTURE OUT TO ITS EAST. A COORDINATED SLIGHT
RISK FOR EXCESSIVE RAINFALL FOR DAY 5 IS NOW IN EFFECT FOR
SOUTHERN NEW MEXICO AND SOUTHWESTERN TEXAS. THERE HAS BEEN A
TREND FOR HEAVIER RAINFALL IN THE LATEST MODEL GUIDANCE ACROSS
CENTRAL AND SOUTHERN TEXAS GOING INTO MONDAY/TUESDAY AS DEEP
MOISTURE CONVERGES NEAR A FRONTAL BOUNDARY.
MUCH OF THE NORTHWESTERN U.S. AS WELL AS NORTHERN CALIFORNIA INTO
PARTS OF THE GREAT BASIN SHOULD HAVE ABOVE NORMAL TEMPERATURES
EACH DAY WITH THE UPPER RIDGE ANCHORED OVER OR NEAR THE REGION,
WITH SOME HIGHS REACHING 10-20 DEGREES ABOVE NORMAL, MAKING IT
FEEL MORE LIKE EARLY SEPTEMBER FOR MANY AREAS. TO THE CONTRARY, A
SERIES OF FRONTS PIVOTING AROUND THE MAIN EASTERN UPPER
TROUGH/CLOSED LOW WILL BRING PROGRESSIVELY COLDER TEMPERATURES TO
AREAS EAST OF THE ROCKIES. THE COOLEST ANOMALIES (UP TO 10-20F
BELOW NORMAL) SHOULD EXTEND FROM THE UPPER MIDWEST INTO GREAT
LAKES AND OHIO VALLEY FOR SEVERAL DAYS AS THE UPPER TROUGH
PERSISTS. THE SOUTHERN PLAINS AND VICINITY WILL BE WARM THROUGH
SATURDAY BUT THEN THIS REGION WILL TREND COOLER AS RAINFALL
SPREADS ACROSS THE REGION.
HAMRICK/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
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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