943
FXUS61 KCLE 281002
AFDCLE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CLEVELAND OH
502 AM EST THU NOV 28 2024
SYNOPSIS
LOW PRESSURE EXITS TO THE EAST COAST AREA TODAY. A BROAD UPPER
LEVEL LOW SETTLES INTO THE GREAT LAKES FOR THE FORESEEABLE
FUTURE. ONSHORE WINDS MAKE FOR A PROLONGED LAKE EFFECT SNOW
EVENT BEGINNING TONIGHT THROUGH THE WEEKEND.
NEAR TERM /THROUGH FRIDAY/
BROAD CYCLONIC FLOW ALOFT TAKES OVER AS SURFACE LOW PRESSURE EXITS
THE REGION. SURFACE FLOW BECOMES COLD ADVECTIVE OFF LAKE ERIE,
QUICKLY TRANSITIONING TO A LAKE EFFECT SETUP THAT WILL LINGER WELL
INTO THE WEEKEND.
FLOW BEGINS TO TURN WESTERLY AFTER 00Z FRIDAY WITH A GOOD FETCH OFF
LAKE ERIE THAT WILL PUSH INLAND EAST OF CLEVELAND IN EASTERN
CUYAHOGA COUNTY. SNOW BEGINS ON THE INEFFICIENT SIDE WITH SNOW
RATIOS DOWN AROUND 7:1 AND AIR TEMPERATURES STILL WORKING THEIR WAY
DOWN TOWARDS FREEZING. EXPECTING THE FIRST SIGNIFICANT ACCUMULATIONS
TO COME IN THE 06-12Z FRIDAY TIME FRAME, BUT THE BAND SETTING UP
SHOULD BECOME TRANSIENT FAIRLY SOON INTO THE EVENT. THE FRIDAY
PERIOD GETS A LITTLE TRICKY. WHILE MODELS ARE BASICALLY ALL
FORECASTING A SURFACE TROUGH SETTING UP OVER/IN THE VICINITY OF LAKE
ERIE ALONG ITS MAXIMUM FETCH, THE STRENGTH AND EXACT LOCATION IS NOT
NECESSARILY CONSISTENT WITHIN THE MODELS. THE STRENGTH OF THE
SURFACE TROUGH COMES INTO EFFECT WITH THE DEGREE OF THE CONVERGENCE
OF THE SURFACE WINDS AND ULTIMATELY THE 925MB F-GEN, WHICH IN
CERTAIN CASES WOULD PULL THE BAND MORE TOWARDS THE SHORE OR EVEN A
BIT OFFSHORE. FOR NOW, GOING TO KEEP WITH THE SOLUTIONS WE HAVE BEEN
RUNNING WITH OVER THE PAST COUPLE OF DAYS WITH OUR FAR NE OH AND NW
PA ZONES GETTING HIT WITH AN OSCILLATING BAND OF LAKE EFFECT SNOW,
BUT WILL NEED TO CAREFULLY WATCH MODEL UPDATES TO KEEP UP WITH THIS
TROUGH PLACEMENT. SNOW SHOULD GET MORE EFFICIENT WITH TEMPERATURE
DROPS AND SUBSEQUENT RATIOS CLIMBING INTO THE 12-15:1 RANGE HEADING
INTO EARLY FRIDAY. ONCE WE GET INTO FRIDAY, ONE ADDITIONAL CONCERN
WITH THE FORECAST IS THAT THE WINDS COMING OFF LAKE ERIE WILL
STRENGTHEN TO 25-35MPH, REDUCING PARCEL RESIDENCE TIME OVER THE
WATER AND PLAYING HAVOC WITH THE DENDRITES. THIS WOULD ULTIMATELY BE
DETRIMENTAL TO THE SNOW AMOUNTS IN THE FORECAST. IN THE END, THE
SNOW AMOUNT FORECAST IS THE NET RESULT OF THE FORECAST PARAMETERS
WHICH CONTINUES TO SHOW A SIZABLE EARLY SEASON LAKE EFFECT EVENT FOR
THE LAKE EFFECT PRONE PORTIONS OF THE FORECAST AREA. GIVEN THAT THIS
IS AN EVENT ON THE MESOSCALE LEVEL, SOME FINE TUNING ADJUSTMENTS
SHOULD CONTINUE TO BE EXPECTED IN UPCOMING FORECASTS TO HELP NARROW
DOWN THE PLACEMENT OF THE LAKE EFFECT BAND AND ITS EVOLUTION THROUGH
TIME.
SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/
LAKE EFFECT SNOW WILL BE ONGOING ACROSS NORTHEAST OHIO AND NORTHWEST
PENNSYLVANIA AT THE START OF THE SHORT TERM FORECAST PERIOD ON
FRIDAY NIGHT. THE UPPER LEVEL TROUGH AXIS THAT WILL MOVE THROUGH THE
REGION ON FRIDAY TO ENHANCE SNOW WILL DEPART TO THE EAST FOR FRIDAY
NIGHT INTO SATURDAY AND FLOW WILL START TO BACK. THIS WILL ALLOW FOR
ANY ORGANIZED LAKE EFFECT SNOW BANDS TO START LIFTING NORTH ACROSS
THE REGION AND LIKELY ENTIRELY OVER THE LAKE. HAVE STARTED THE TREND
IN THE FORECAST TO NUDGE THE HIGHEST POPS AND SNOWFALL ACCUMULATIONS
NORTH THROUGH SATURDAY. A SHORTWAVE IN THE BROADER TROUGH OVER THE
REGION WILL ENTER ON SUNDAY AND ALLOW FOR SNOW TO START PUSHING BACK
TOWARD THE FORECAST AREA AS FLOW VEERS AND HAVE POPS INCREASING
ACROSS THE AREA FOR SUNDAY AND SUNDAY NIGHT. WITH THE PACKAGE THIS
MORNING, WE HAVE DECIDED TO UPGRADE TO A LAKE EFFECT SNOW WARNING
FOR THE NE OH/NW PA SNOW BELT THROUGH 10 AM SATURDAY, WHICH IS
SIGNIFICANTLY SHORTENED FROM THE INITIAL WATCH THAT WAS VALID
THROUGH 7 AM ON MONDAY. THE RATIONALE WAS TO HIGHLIGHT THE HIGHER
CONFIDENCE PERIOD OF SNOW THROUGH FRIDAY NIGHT THAT WILL BRING UP TO
18 INCHES OF SNOW TO PORTIONS OF THE OH AND PA SNOW BELT AND ACCOUNT
FOR A LACKLUSTER TIME PERIOD ON SATURDAY AND SATURDAY NIGHT, WHEN
SNOW WILL BE MARGINAL FOR MUCH OF THE AREA. WE CAN ALSO ALLOW MORE
TIME FOR DETAILS ON THE SNOW EARLY NEXT WEEK TO BECOME MORE CLEAR.
WE WILL EVALUATE THE HEADLINES THROUGH THE NEXT COUPLE OF DAYS AND
EITHER EXTEND OR REPLACE THEM AS NEEDED AS THE FIRST ROUND OF LAKE
EFFECT SNOW ENDS ON SATURDAY MORNING AND THE NEXT ROUND BEGINS ON
SUNDAY. TEMPERATURES THROUGH THE PERIOD WILL BE COLD WITH HIGHS
BELOW FREEZING AND LOWS IN THE TEENS FOR MOST.
LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/
BOTTOM LINE, UP FRONT - THERE WILL BE POTENTIAL FOR CONTINUED LAKE
EFFECT SNOW ON MONDAY INTO TUESDAY AND THERE COULD BE A NEED FOR
ADDITIONAL WINTER HEADLINES AS DETAILS BECOME MORE CLEAR.
THE UPPER LEVEL PATTERN STARTS TO MOVE MORE PROGRESSIVELY ON MONDAY
WITH THE FIRST OF THREE SHORTWAVES MOVING THROUGH THE FLOW ALOFT.
THESE SHORTWAVES WILL FINALLY ALLOW FOR THE CLOSED UPPER LOW OVER
ONTARIO TO FLUSH OUT OF THE REGION AND START ALLOWING FOR SOME
CHANGES TO THE LAKE EFFECT PATTERN. FOR MONDAY, BELIEVE THAT THERE
WILL BE SOME EFFICIENT SNOWFALL WITHIN THE FORECAST AREA AS THE
THERMODYNAMICS REMAIN STRONG FOR LAKE EFFECT WITH AROUND -10 C AT
850 MB OVER A LAKE THAT SHOULD BE AT ABOUT 5 C OR SO ON MONDAY.
HOWEVER, THE SHORTWAVE MOVING THROUGH THE REGION SHOULD PROVIDE SOME
EXTRA LIFT TO ALLOW FOR MORE WIDESPREAD SNOWFALL. IN ADDITION, THE
FETCH WILL SHIFT TO THE NORTHWEST AND WHILE THIS WILL BE A SHORTER
FETCH OFF LAKE ERIE, THIS PATTERN WILL START TO PUT THE EFFECTS OF
THE OTHER GREAT LAKES IN PLAY, ESPECIALLY LAKE HURON. WHEREVER THAT
CONNECTION SETS UP, THERE SHOULD BE ENOUGH PRESENT TO ALLOW FOR
ANOTHER ROUND OF HEADLINE-WORTHY (POTENTIALLY WARNING LEVEL) SNOW ON
MONDAY. ANOTHER SHORTWAVE APPEARS TO DIG INTO THE REGION ON TUESDAY
AND ALLOW FOR THE SAME THING TO HAPPEN. HOWEVER, WITH THIS WAVE,
ADDITIONAL COLD AIR ADVECTION WILL SURGE INTO THE REGION AND 850 MB
TEMPERATURES MAY DIP TO -12 TO -13 C, WHICH WILL ONLY INCREASE THE
POTENTIAL LAKE EFFECT INSTABILITY AND ENHANCE ANY SNOW ACROSS THE
REGION. THE QUESTION JUST STARTS TO BECOME ABOUT IF THERE IS ENOUGH
MOISTURE, AS THESE WAVES WILL START BRINGING DOWN SOME DRIER,
CONTINENTAL AIR MASS INTO THE REGION. ANOTHER WAVE WILL MOVE THROUGH
THE GREAT LAKES ON WEDNESDAY; HOWEVER, THERE APPEARS TO BE A DEEPER
PULL OF WARM AIR AHEAD OF IT, WHICH MAY ALLOW FOR SNOW TO CHANGE
BACK TO RAIN. TEMPERATURES WILL BE COLDER THAN NORMAL FOR THE
PERIOD, BUT TRENDING UP LATER IN THE WEEK.
AVIATION /06Z THURSDAY THROUGH MONDAY/
RAIN/SNOW MIX OR ALL SNOW FOR FDY/MFD/CAK/YNG TONIGHT, AND ALL
RAIN FURTHER NORTH CLOSER TO THE WARMER LAKESHORE AREAS AS LOW
PRESSURE TRACKS WEST TO EAST THROUGH THE OHIO VALLEY. MAINLY
MVFR RIGHT NOW, BUT STILL EXPECT IT TO WORSEN TO IFR CEILINGS
AND VISIBILITIES DURING THE OVERNIGHT PERIOD FOR MOST OF THE
TERMINALS, WITH SOME LIFR POSSIBLE FOR A FEW HOURS AS WELL.
WINDS TURNING NORTHWESTERLY 10KTS. IMPROVEMENT TO THE FLIGHT
CATEGORIES DURING THE AFTERNOON WITH THE EXIT OF THE LOW
PRESSURE SYSTEM. LAKE EFFECT AREAS WILL SEE SNOW DEVELOPING
AFTER 06Z FRIDAY.
OUTLOOK...NON-VFR LIKELY IN PERIODIC LAKE-EFFECT SNOW IS
EXPECTED THURSDAY NIGHT THROUGH MONDAY. 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
LOW PRESSURE OVER THE OHIO VALLEY IS DEEPENING AS IT MOVES EAST
TOWARD THE EAST COAST AND AS IT HELPS EXTEND A COLD FRONT ACROSS THE
LAKE. NORTHERLY FLOW IS EXPECTED TO QUICKLY INCREASE OVER THE NEXT
SEVERAL HOURS AND WAVES WILL INCREASE TO 4 FT OR GREATER. THEREFORE,
WILL MAINTAIN THE CURRENT SMALL CRAFT ADVISORY START TIME IN A FEW
HOURS. BEHIND THE FRONT TONIGHT, WEST WINDS WILL BECOME FAVORED OVER
THE LAKE AND REMAIN THAT WAY THROUGH FRIDAY AND INTO THE WEEKEND AS
A TROUGH SETTLES ACROSS THE GREAT LAKES. WINDS MAY GET OVER 20 KT
OVER THE WESTERN BASIN AND THERE MAY NEED TO BE AN EXTENSION IN THE
SMALL CRAFT ADVISORY HEADLINE WESTWARD. WINDS MAY SWAY BETWEEN WEST-
SOUTHWEST AND WEST-NORTHWEST THROUGH THE WEEKEND AS LAKE EFFECT SNOW
BANDS WILL DEVELOP OVER THE BASIN AND ALLOW FOR SOME SLIGHT WIND
CHANGES BUT OVERALL WINDS SHOULD UTILIZE THE LONG FETCH OF THE LAKE
AND ALLOW FOR WAVES TO INCREASE GREATLY. THE SMALL CRAFT ADVISORY IS
CURRENTLY IN EFFECT UNTIL 12Z MONDAY BUT THE TROUGH SHOULD BE IN
PLACE THROUGH TUESDAY AND EXTENSIONS WILL LIKELY BE NEEDED.
CLE WATCHES/WARNINGS/ADVISORIES
OH...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 10 AM EST
SATURDAY FOR OHZ011.
LAKE EFFECT SNOW WARNING FROM MIDNIGHT TONIGHT TO 10 AM EST
SATURDAY FOR OHZ012>014-089.
PA...LAKE EFFECT SNOW WARNING FROM MIDNIGHT TONIGHT TO 10 AM EST
SATURDAY FOR PAZ001>003.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST MONDAY FOR LEZ144>149.
SYNOPSIS...26
NEAR TERM...26
SHORT TERM...SEFCOVIC
LONG TERM...SEFCOVIC
AVIATION...26
MARINE...SEFCOVIC
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