101
FXUS61 KCLE 292104
AFDCLE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CLEVELAND OH
404 PM EST FRI NOV 29 2024
SYNOPSIS
A LOW PRESSURE SYSTEM NORTH OF THE REGION WILL KEEP A SURFACE TROUGH
ACROSS THE AREA INTO THE START OF NEXT WEEK. ANOTHER LOW PRESSURE
WILL MOVE EAST ACROSS THE NORTHERN GREAT LAKES, IMPACTING THE AREA
AGAIN FOR MID-WEEK.
NEAR TERM /THROUGH SATURDAY NIGHT/
A POTENTIALLY HISTORIC LAKE-EFFECT SNOWSTORM WILL CONTINUE
ACROSS FAR NE OHIO AND NW PA TONIGHT THROUGH SATURDAY MORNING AS
A LONG FETCH, WESTERLY FLOW OF COLD AIR INTERACTS WITH NEAR
RECORD WARM LAKE TEMPERATURES.
IN TERMS OF THE PATTERN, A CLOSED MID-LEVEL LOW NEAR JAMES BAY
WILL GRADUALLY PIVOT INTO QUEBEC THROUGH THE WEEKEND AS THE
ASSOCIATED BROAD, DEEP MID/UPPER TROUGH CONTINUES ACROSS THE
GREAT LAKES. THIS WILL MAINTAIN A BROAD CYCLONIC FLOW OF COLD
AIR AND SUFFICIENT SYNOPTIC MOISTURE ACROSS THE GREAT LAKES,
WITH A SERIES OF SHORTWAVES OSCILLATING THE BOUNDARY LAYER WIND
FIELDS, CAUSING LAKE-EFFECT BANDS TO WOBBLE. LAKE INDUCED
INSTABILITY WILL REMAIN STRONG TO EXTREME THROUGH THE PERIOD, AS
EQUILIBRIUM LEVELS REACH 20 THOUSAND FEET AT TIMES WITH VERY
STEEP LAPSE RATES.
DOPPLER RADAR LOOPS THIS AFTERNOON SHOW THAT THE MAIN BAND HAS
BECOME WIDER AND MORE CELLULAR FROM THE WESTERN BASIN OF LAKE
ERIE TO NORTHEASTERN LAKE, NORTHERN ASHTABULA, ERIE, AND EXTREME
NORTHERN CRAWFORD COUNTIES. THIS IS DUE TO DAYTIME HEATING
SLIGHTLY DISRUPTING THE BOUNDARY LAYER THERMODYNAMICS OVER THE
LAKE AND THE INSTABILITY SNOW SHOWERS DEVELOPING ON LAND.
HOWEVER, THE BOUNDARY LAYER FLOW HAS BEEN STEADILY VEERING MORE
WESTERLY, AND THIS IS CAUSING THE BAND TO SAG SLOWLY SOUTHWARD.
EXPECT THAT ONCE THE SUN SETS, THE BAND WILL QUICKLY REGAIN
ORGANIZATION AND TURN INTO A HIGHLY FOCUSED, INTENSE PLUME
TARGETING EASTERN LAKE, NE GEAUGA, NORTHERN/CENTRAL ASHTABULA,
ERIE, AND NORTHERN CRAWFORD COUNTIES AS A MAINLY 270 DEGREE FLOW
LOCKS IN FROM THIS EVENING THROUGH MUCH OF THE NIGHT. THE HREF
MEMBERS CONTINUE TO SHOW THE TYPICAL SOUTH BIAS, BUT THEY HAVE
NOT BEEN TERRIBLE THIS AFTERNOON OVERALL. THE RGEM CONTINUES TO
HAVE THE BEST HANDLE ON BAND PLACEMENT, ALTHOUGH A LITTLE TOO
FAR NORTH. WITH THIS IN MIND, OPTED FOR A PLACEMENT BETWEEN THE
RGEM AND HREF. THIS IS A SERIOUS SITUATION BECAUSE THIS PLACES
THE HEAVIEST SNOW THIS EVENING AND TONIGHT OVER AREAS THAT HAVE
ALREADY BEEN HIT VERY HARD TODAY. REPORTS FROM NORTHERN ERIE
COUNTY HAVE BEEN IN THE 15 TO 25 INCH RANGE SINCE THE SNOW BEGAN
LATE LAST NIGHT, WITH REPORTS OF OVER 8 INCHES IN 2.5 HOURS
AROUND MIDDAY TODAY! ADDITIONAL SNOWFALL OF 18 TO 24 INCHES IS
LIKELY IN NORTHERN ERIE COUNTY THROUGH SATURDAY MORNING, WITH
LOCALLY UP TO 30 INCHES. ADDITIONAL SNOWFALL OF 12-18 INCHES
WITH LOCALLY UP TO 24 INCHES IS EXPECTED THROUGH SATURDAY
MORNING IN EASTERN LAKE AND NORTHERN ASHTABULA COUNTIES. JUST
SOUTH OF THIS SWATH, ADDITIONAL AMOUNTS OF 8-12 INCHES ARE
EXPECTED FROM ABOUT NE GEAUGA TO CENTRAL ASHTABULA COUNTIES.
THIS WILL PLACE STORM TOTALS IN THE 3 TO 4 FOOT RANGE IN THE
HARDEST HIT AREAS, WITH LOCALLY UP TO 50 INCHES IN NORTHERN ERIE
COUNTY!
IN TERMS OF HEADLINE DECISIONS, OPTED TO KEEP ONGOING LAKE-
EFFECT SNOW WARNINGS THROUGH 15Z SATURDAY FOR LAKE, GEAUGA,
ASHTABULA, AND ERIE AND CRAWFORD COUNTIES. GEAUGA IS CLOSE, BUT
THERE IS ENOUGH CONFIDENCE THAT THE BAND WILL CLIP THE THOMPSON
AREA THIS EVENING AND THE FIRST HALF OF TONIGHT TO BRING WARNING
AMOUNTS TO THE FAR NE PARTS OF THE COUNTY. CUYAHOGA COUNTY HAS
THE GREATEST "BUST" POTENTIAL. THE BAND COULD AFFECT EUCLID
(EXTREME NE CUYAHOGA) FOR SEVERAL HOURS THIS EVENING AND EARLY
TONIGHT, SO KEPT A SMALL AREA OF ADDITIONAL SNOWFALL NEAR 3
INCHES. THESE AMOUNTS COULD BE A COUPLE OF INCHES HIGHER OR
LOWER DEPENDING ON HOW IT ORIENTS AFTER DARK, SO THERE'S A
POSSIBILITY THE ADVISORY MAY NEED TO BE CANCELLED. IF THE BAND
ORIENTS SLIGHTLY FARTHER SOUTH, THEN THE ADVISORY IS FINE. THIS
WILL BE WATCHED THIS EVENING.
LATE TONIGHT AND SATURDAY, THE BOUNDARY LAYER FLOW IS STILL
PROJECTED TO BACK RATHER QUICKLY AHEAD OF A STRONGER SHORTWAVE
DROPPING INTO THE GREAT LAKES. THIS WILL START TO STEADILY LIFT
THE BAND NORTHWARD BEFORE SUNRISE SATURDAY AND THROUGH MIDDAY.
TRENDS HAVE BEEN FOR THIS TO HAPPEN A LITTLE SLOWER, SO HELD
ONTO HIGHER POPS ALONG THE ERIE, PA LAKESHORE THROUGH EARLY
AFTERNOON, BUT IT WILL END ON THE OHIO LAKESHORE 12-15Z. BY MID
AFTERNOON, ALL OF THE SNOW SHOULD BE OVER THE LAKE AS THE BAND
REORIENTS INTO THE BUFFALO AREA. THIS WILL GIVE A NEEDED BREAK
TO DIG OUT.
UNFORTUNATELY, THE AFOREMENTIONED SHORTWAVE WILL MOVE INTO THE
SOUTHERN GREAT LAKES SATURDAY NIGHT AND START TO VEER THE FLOW
MORE WESTERLY AGAIN. THIS WILL START TO PUSH THE BAND BACK INTO
NW PA AND EXTREME NE OHIO OVERNIGHT. THERE WILL BE STRONGER
BOUNDARY LAYER SHEAR SATURDAY NIGHT, SO THAT WILL LIKELY MAKE
THE BAND MORE RAGGED AND CELLULAR, BUT IT WILL START TO SNOW AT
LEAST MODERATELY ALONG THE LAKESHORES OF FAR NE OHIO AND NW PA
AGAIN. THE BAND WILL LIKELY BE SLOWER THAN GUIDANCE TO MOVE BACK
SOUTH DUE TO LAKE AGGREGATE TROUGHING, SO SLOWLY EXPANDED POPS
BACK SOUTH AND WESTWARD. THIS WILL TAKE US INTO PART 2 OF THIS
LAKE-EFFECT SNOWSTORM, SO SEE THE SHORT TERM AND LONG TERM
SECTIONS FOR DETAILS ON THAT.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
THE LARGE AND COLD CYCLONIC FLOW WILL CONTINUE SUNDAY INTO MONDAY
BUT THERE WILL BE SOME SUBTLE CHANGES IN THE LOW LEVELS WHICH WILL
SHIFT THE LAKE EFFECT SNOW BANDS. ON SUNDAY, CENTER OF MID LEVEL
TROUGH WILL MOVE TO JUST NORTH OF NEW YORK STATE IN SOUTHERN QUEBEC.
THE LOW LEVEL FLOW WILL START OUT ON SUNDAY FROM THE WEST-SOUTHWEST
WHICH WILL KEEP ONGOING LAKE EFFECT SNOW BANDS HUGGING NEAR THE
LAKESHORE AREA OF FAR NEOH AND NWPA THROUGH THE AFTERNOON. A SURFACE
TROUGH WILL PUSH ACROSS THE AREA SUNDAY NIGHT. THE LOW LEVEL FLOW
WILL BECOME MORE WEST-NORTHWEST SUNDAY NIGHT THROUGH MONDAY NIGHT.
THIS CHANGE IN THE FLOW WILL SHIFT THE POTENTIAL OF LAKE EFFECT SNOW
BANDS MORE INTO NORTH CENTRAL AND NORTHEAST OHIO AS WELL AS NWPA.
SOME OF THE SECONDARY SNOWBELT AREAS WILL COME INTO PLAY WITH THE
LAKE EFFECT SNOW POTENTIAL, INCLUDING MORE OF THE CLEVELAND METRO
AREA. THERE COULD ALSO BE A LAKE HURON CONNECTION THAT DEVELOPS FOR
NWPA AND THE ERIE PA AREA LATE MONDAY INTO MONDAY NIGHT. ADDITIONAL
HEAVY SNOWFALL IS VERY POSSIBLE FOR MORE OF THE CLEVELAND AREA AND
EASTWARD TOWARDS NWPA. ADDITIONAL WINTER HEADLINES WILL LIKELY BE
NEEDED FOR SOME PORTION OF NEOH AND NWPA. AREAS OUTSIDE OF THE
SNOWBELT WILL HAVE RELATIVELY QUIET WEATHER WITH SOME PASSING LIGHT
SNOW SHOWERS FROM TIME TO TIME WITH LITTLE TO NO ACCUMULATIONS OR
IMPACTS. TEMPERATURES WILL BE COLD AND BELOW AVERAGE SUNDAY INTO
MONDAY WITH HIGHS IN THE 30S AND OVERNIGHT LOWS IN THE UPPER TEENS
AND 20S.
LONG TERM /TUESDAY THROUGH FRIDAY/
THE UPPER LEVEL WEATHER PATTERN WILL START TO CHANGE ON TUESDAY. THE
UPPER LEVEL TROUGH WILL START TO PULL AWAY LATE ON TUESDAY. THE LOW
LEVEL FLOW WILL START OUT WESTERLY ON TUESDAY WHICH WILL PUSH THE
LAKE EFFECT SNOW BANDS INTO FAR NEOH AND NWPA DURING THE DAY. THE
FLOW BECOMES MORE SOUTHWESTERLY BY TUESDAY EVENING AND PUSH THE LAKE
EFFECT EITHER OUT INTO LAKE ERIE OR HUGGING THE LAKESHORE OF FAR
NEOH AND NWPA TUESDAY NIGHT. THE UPPER LEVEL PATTERN BRIEFLY WILL
BE MORE ZONAL BY TUESDAY NIGHT. A STRONG SHORTWAVE TROUGH WILL DIVE
DOWN THROUGH THE GREAT LAKES REGION ON WEDNESDAY WITH A DEEPENING
SURFACE LOW TRACKING THROUGH THE UPPER GREAT LAKES. AN AREA OF SNOW
WILL SPREAD OVER MUCH OF THE REGION BY WEDNESDAY MORNING WITH A WARM
FRONT. SNOW, BRIEFLY MIXING WITH RAIN AT TIMES ON WEDNESDAY IS
EXPECTED WITH LIGHT SNOWFALL ACCUMULATIONS POSSIBLE AREAWIDE. AS THE
STRONG LOW PRESSURE SYSTEM PASSES BY TO OUR NORTH, A COLD FRONT WILL
MOVE THROUGH WEDNESDAY EVENING. IT WILL BECOME WINDY WEDNESDAY
THROUGH THURSDAY WITH GUSTS EASILY UP TO 35 MPH.THE AREAWIDE OF SNOW
WILL TRANSITION BACK TO ORGANIZED LAKE EFFECT SNOW BANDS FOR BOTH
THE PRIMARY AND MAYBE THE SECONDARY SNOWBELT WEDNESDAY NIGHT THROUGH
THURSDAY NIGHT WITH ADDITIONAL LOCALIZED HEAVY SNOW POSSIBLE.
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
HEAVY LAKE-EFFECT SNOW WILL REMAIN THE BIGGEST PROBLEM THROUGH
THE TAF CYCLE, BUT THIS WILL BE CONFINED TO KERI. THAT TERMINAL
HAS SEEN VISIBILITIES BELOW ONE QUARTER MILE SINCE ABOUT 12Z,
AND EXPECT THIS TO CONTINUE THROUGH AT LEAST EARLY EVENING AS
THE LAKE-EFFECT BAND DOES NOT LOOK TO MOVE MUCH. THIS WILL KEEP
A LONG PERIOD OF LIFR AT KERI, PERHAPS SLOWLY IMPROVING TO IFR
AND MVFR TONIGHT AS THE BAND SHIFTS, BUT OVERALL, EXPECT
FREQUENT SNOW AND VERY POOR CONDITIONS TO CONTINUE THROUGH
SATURDAY MORNING.
OUTSIDE OF THE BAND, THE OTHER SITES WILL SEE OCCASIONAL
FLURRIES AND LIGHT SNOW WITH MVFR TO VFR CONDITIONS THIS
AFTERNOON AND EARLY EVENING BEFORE DRYING OUT AND TURNING
MAINLY VFR TONIGHT AND SATURDAY MORNING.
W TO WSW WINDS OF 10-20 KNOTS WITH GUSTS OF 20-30 KNOTS THIS
AFTERNOON AND EVENING WILL DECREASE TO MAINLY 10-15 KNOTS
TONIGHT WHILE TURNING MORE TOWARD THE SW. GUSTS OF 20-25 KNOTS
WILL AGAIN DEVELOP BY LATE SATURDAY MORNING.
OUTLOOK...NON-VFR LIKELY IN PERIODIC LAKE-EFFECT SNOW THROUGH
TUESDAY. THE HEAVIEST AND MOST-PERSISTENT LAKE-EFFECT SNOW IN
OUR REGION IS EXPECTED TO IMPACT THE PRIMARY SNOWBELT IN FAR
NORTHEAST OHIO AND NORTHWEST PENNSYLVANIA.
MARINE
A LARGE LOW PRESSURE SYSTEM NORTH OF THE GREAT LAKES WILL KEEP WINDS
ELEVATED AND ROUGH CONDITIONS ON LAKE ERIE THIS WEEKEND THROUGH
EARLY NEXT WEEK. WINDS THIS WEEKEND THROUGH EARLY NEXT WEEK WILL
GENERALLY BE FROM THE WEST 15 TO 25+ PLUS WITH GUSTS UP TO 35 KNOTS
AT TIMES WITH ORGANIZED SNOW SQUALLS. THERE MIGHT BE SOME SLIGHT
VARIATION OF THE WESTERLY FLOW AT TIMES, TURNING MORE WEST-NORTHWEST
OR WEST-SOUTHWEST. WAVES WILL REMAIN HIGH ESPECIALLY FOR THE CENTRAL
AND EASTERN BASIN OF LAKE ERIE OVER THE NEXT SEVERAL DAYS. SMALL
CRAFT ADVISORY ARE IN EFFECT AND MAY NEED TO BE EXTENDED FURTHER IN
DURATION OVER TIME WITH NO CHANGES IN THE WEATHER PATTERN EXPECTED
THROUGH MIDDLE OF NEXT WEEK. BY WEDNESDAY, A STRONG LOW PRESSURE
SYSTEM MAY DEVELOP AND TRACK ACROSS THE UPPER GREAT LAKES WHICH WILL
CHANGE OUR WINDS BRIEFLY FROM THE SOUTH 20 TO 30 KNOTS BEFORE
RETURNING TO WEST-NORTHWEST WINDS FOLLOWING A COLD FRONT. LOW WATER
ADVISORY REMAINS IN EFFECT INTO SATURDAY WITH THE LATEST WATER LEVEL
AT TOLEDO 2.7 INCHES BELOW THE LOW WATER DATUM. THE CRITICAL WATER
LEVEL FOR SAFE NAVIGATION IS 3 INCHES ABOVE THE LOW WATER DATUM.
WATER LEVELS WILL SLOWLY INCREASE AND IMPROVE LATE ON SATURDAY OVER
THE WESTERN BASIN OF LAKE ERIE.
CLE WATCHES/WARNINGS/ADVISORIES
OH...WINTER WEATHER ADVISORY UNTIL 10 AM EST SATURDAY FOR OHZ011.
LAKE EFFECT SNOW WARNING UNTIL 10 AM EST SATURDAY FOR
OHZ012>014-089.
PA...LAKE EFFECT SNOW WARNING UNTIL 10 AM EST SATURDAY FOR
PAZ001>003.
MARINE...LOW WATER ADVISORY UNTIL 1 PM EST SATURDAY FOR LEZ142>144-
162>164.
SMALL CRAFT ADVISORY UNTIL 10 AM EST SATURDAY FOR LEZ142-143.
SMALL CRAFT ADVISORY UNTIL 7 AM EST MONDAY FOR LEZ144>149.
SYNOPSIS...GARUCKAS
NEAR TERM...GARUCKAS
SHORT TERM...GRIFFIN
LONG TERM...GRIFFIN
AVIATION...GARUCKAS
MARINE...GRIFFIN
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