767
FXUS02 KWBC 030628
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
228 AM EDT MON OCT 03 2022
VALID 12Z THU OCT 06 2022 - 12Z MON OCT 10 2022
..OVERVIEW
A STUBBORN COMPACT UPPER LOW/SHORTWAVE STUCK OVER THE MID-ATLANTIC
REGION DURING THE SHORT RANGE PERIOD WILL FINALLY BE DEPARTING OFF
THE NORTHEAST COAST BY THE START OF THE MEDIUM RANGE/THURSDAY. IN
IT'S WAKE, ANOTHER SHORTWAVE WILL DIVE INTO THE UPPER GREAT LAKES
FROM CANADA SETTING UP A PROLONGED PERIOD OF UPPER TROUGHING OVER
THE EASTERN U.S., PERIODICALLY REINFORCED BY SEVERAL PIECES OF
ENERGY ROUNDING THE TOP OF A BUILDING AND BLOCKY RIDGE OVER THE
WEST. DESPITE THE SOMEWHAT AMPLIFIED PATTERN, RELATIVELY QUIET
WEATHER CONDITIONS ARE EXPECTED ACROSS THE CONUS THROUGH NEXT
WEEKEND BESIDES SOME MONSOONAL MOISTURE AND WEAK ENERGY OVER THE
SOUTHWEST, AND A POTENT COLD FRONT PUSHING ACROSS THE CENTRAL AND
EASTERN U.S. LEADING TO RAIN PARTICULARLY IN THE GREAT LAKES
REGION ALONG WITH CONSIDERABLY COOLER TEMPERATURES BEHIND THE
FRONT.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
WITH THE PATTERN BECOMING DOMINATED BY THE GENERAL RIDGE IN THE
WEST AND TROUGHING IN THE EAST, MODEL GUIDANCE REMAINS AGREEABLE
WITH THE OVERALL AMPLIFIED SYNOPTIC PATTERN, BUT SMALLER SCALE
DETAILS ARE MORE UNCERTAIN. GUIDANCE SHOWS GOOD ENOUGH AGREEMENT
WITH THE INITIAL SHORTWAVE DIVING INTO THE GREAT LAKES
THURSDAY-FRIDAY FOR A PURELY DETERMINISTIC MODEL BLEND. AFTER
THIS, DETAILS BECOME INCREASINGLY UNCERTAIN AS MULTIPLE PIECES OF
ENERGY ROUND THE TOP OF THE BLOCKY WESTERN RIDGE INTO THE NORTHERN
HIGH PLAINS AND EVENTUALLY ACTING TO REINFORCE THE TROUGH IN THE
EAST. MODELS ALSO CANNOT AGREE HOW MUCH THE RIDGE OVER THE WEST
MAY BREAK DOWN BY THE END OF THE PERIOD AS ENERGY FROM THE GULF OF
ALASKA MOVES SOUTHWARD. WPC PREFERRED A BLEND INCREASINGLY TOWARDS
THE ENSEMBLE MEANS DAYS 5-7 TO HELP MITIGATE SOME OF THE
DIFFERENCES. THIS ALSO MAINTAINS GOOD CONTINUITY WITH THE PREVIOUS
FORECAST. THE QPF WAS BASED LARGELY ON THE 01Z NATIONAL BLEND OF
MODELS, BUT WITH A WIDER FOOTPRINT FOR LIGHT AMOUNTS ADDED ACROSS
MUCH OF THE COUNTRY AS THIS UNDERFORECAST OF LOW AMOUNTS FROM THE
NBM IS A KNOWN BIAS.
..WEATHER/HAZARDS HIGHLIGHTS
MONSOONAL MOISTURE INTO THE SOUTHWEST WILL CONTINUE TO DRIVE SOME
DIURNAL SHOWERS AND THUNDERSTORMS, WITH LOCALLY HEAVY RAINFALL
POSSIBLE IN SOME SPOTS. RAINFALL INTENSITY MAY WANE AFTER
THURSDAY, BUT SHOWERS COULD LINGER THROUGH THE WEEKEND ACROSS THE
FOUR CORNERS STATES. TO THE NORTH, A COLD FRONT SHIFTING ACROSS
THE MIDWEST AND GREAT LAKES MAY BRING SOME LIGHT RAIN MAINLY
AROUND THURSDAY, AND LAKE ENHANCED SHOWERS IN THE WESTERLY FLOW
BEHIND THE FRONT FRIDAY AND PERHAPS SATURDAY.
TEMPERATURES OUT WEST WILL BE WARM INTO EARLY NEXT WEEK UNDERNEATH
A BLOCKY UPPER RIDGE, WITH DAYTIME HIGHS OVER THE NORTHWEST 10 TO
15 DEGREES ABOVE NORMAL. DESPITE THE ANOMALIES, THE RESULTING
TEMPERATURES PEAKING IN THE 70S AND 80S (90S FOR PARTS OF
CALIFORNIA) ARE UNLIKELY TO CREATE ANY HEAT RELATED HAZARDS.
CONVERSELY, CANADIAN HIGH PRESSURE SPILLING INTO THE NORTH-CENTRAL
U.S. AND EXPANDING EASTWARD BEHIND THE COLD FRONT WILL RESULT IN
MUCH BELOW NORMAL TEMPERATURES SHIFTING FROM THE NORTHERN PLAINS
INTO THE MIDWEST AND INTO MUCH OF THE EAST THURSDAY-MONDAY.
DAYTIME HIGHS IN SOME LOCATIONS COULD BE 15 TO 20 DEGREES BELOW
AVERAGE WHILE OVERNIGHT TEMPERATURES ARE FORECAST TO DROP INTO THE
30S FOR MANY, AND EVEN 20S FOR NORTH DAKOTA AND NORTHERN MINNESOTA
PARTICULARLY FRIDAY MORNING.
SANTORELLI
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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