Fri evening, Nov 22, 2013 Area Forecast Discussion A minor lake effect snow event is forecast in northeast Ohio. fxus61 kcle 222348 afdcle area forecast discussion national weather service cleveland oh 648 pm est fri nov 22 2013 synopsis... cold front will exit east of the area this evening with a ridge building in from the west. an arctic cold front will push south across the area on saturday with lake effect snow developing. strong high pressure will build east across the ohio valley late sunday. && near term /until 6 am saturday morning/... update...forecast on track. no significant changes. original...area radars continue to show a light drizzle across ne ohio/nw pa late this afternoon. will carry drizzle in the forecast for a few hours with conditions drying out behind the cold front this evening. suface analysis shows one area of low pressure over quebec with a seondary low developing developing north of lake superior. the first low will exit to the northeast tonight with a ridge sharply building into the low levels in advance of the second system. satellite imagery shows the clearing line moving across western lower michigan and will push into nw ohio during the evening. skies will clear except for ne oh/nw pa where enhanced troughing downwind of the lake will aid lake effect cloud developement. temperatures will fall into the upper 20s for inland areas...holding near 30 along the lake. && short term /6 am saturday morning through sunday night/... upper level trough seen on water vapor imagery over canada will surge south over the great lakes region on saturday...pushing an arctic cold front south across the area. the 850mb temperature at churchill manitoba was down to -24c this morning and models are in agreement that the h850 temperature will drop to near -18c by sunday morning. the initial frontal passage will lack moisture and will just carry chance pops for most areas except downwind of lake erie. those areas will see a quick burst of snow with the front and could result in up to an inch of snow accumulation over the higher terrain. a break is expected before the lake effect snow ramps up during the evening as the moisture depth increases with the passage of the upper level trough. the combination of extreme instability over the lake and upslope northwesterly flow will allow lake effect snow showers to fill in across the snow belt. the heaviest accumulations are expected in nw pa where models indicate we will establish a lake huron connection. snowfall rates beneath this band could be 2 inches per hour but hard to define exactly where this band will set. it looks like fairly high chances of it impacting erie and crawford pa. the airmass is cold enough that not expecting the lake to reduce accumulations enough to leave the lakeshore areas out. accumulations in nw pa will exceed 6 inches in many areas but local amounts could exceed a foot by the time the snow ends if the band becomes stationary. have expanded the les watch to include geauga county where the upslope component will cause enough enhancement for accumulations of 4 to 8 inches. the bulk of this will fall on saturday night with the passage of the upper level trough. the rest of the snow belt will see accumulating snow and lake effect snow advisories may be needed in periphery counties. northwest winds will contribute to blusterly conditions with speeds of 15 to 25 mph and gusts to 35 mph. the snow will have a high snow/liquid ratio (15:1 or even 18:1) given the cold airmass and will blow around easily. strong high pressure over the midwest will expand over the ohio valley on sunday and will be accompanied by very dry air. dewpoints fall into the single digits and teens and snow will decrease in coverage from west to east as this dry air intrudes. the complicating factor of this forecast is how long it will take for snow to decrease...given the limited moisture with the system. decided to let the watches continue for another forecast package to allow additional time to consider the moisture quality and placement of lake effect snow bands before making determination on warnings/advisories. heavy snow also not expected to develop until saturday night. && long term /monday through friday/... very few changes to the long term today as the period looks cold with occasional snow showers. will try to start the period off dry on monday. a system will pass to the north on tuesday and drag a cold front across the region. some warm air advection precip could occur as early as monday night but better chances for measurable precip will come with the front. winds will become favorable for lake effect snow late tuesday through wednesday night. moisture appears to be somewhat limited as it will be a dry airmass. as a result...no more than chance pops for the time being. the surface ridge will move just to east of the area on thursday and then linger on friday. this will prevent an airmass change. high temps the entire week will be a good 10 to 15 degrees below normal. && aviation /23z saturday through wednesday/... difficult forecast for the overnight hours. significant drying...at least at midlevels will be coming in overnight. evening nw gusts will subside some and the winds will back more westerly as temporary ridging nudges toward the area. questions will be what will happen with the current ifr/mvfr ceilings. most model guidance wants to clear or scatter that out leaving vfr conditions for morning. one model...the hrrr would like to redevelop at least an mvfr ceiling across the west after 09z and never really get rid of a non-vfr ceiling across the east. have trended the forecast in this more pessimistic direction. models have been too fast all day...and our current ceiling situation has hung on longer than it was suppose to. for saturday...next trough will drop south across the area for the afternoon hours. some scattered snow activity possible with this...the snow showers likely for the snowbelt. this will return conditions to mvfr or lower. winds will also be gusty saturday...with 25 knots for most...30 knots for some. for the extended portion of the cle taf...winds will remain gusty even after 00z sun. outlook...non vfr mainly over ne oh and nw pa saturday night through sunday because of lake effect. non vfr returning late monday night into tuesday and continuing across ne oh/nw pa on wednesday. && marine... with the exception of a few hours later tonight will likely see small craft conditions the entire period. nw flow will continue tonight through sunday. speeds will increase late saturday as a secondary cold front crosses the lake. could get sustained winds in the 25 to 30 knot range for several hours behind the front. winds will become sw on monday as surface ridge crosses the lake. speeds will remain up with sustained winds of at least 20 knots. another cold front will cross the lake on tuesday causing the flow to return to the nw. strong north to nw flow will then continue through wednesday. && cle watches/warnings/advisories... oh...lake effect snow watch from saturday evening through sunday evening for ohz013-014-089. pa...lake effect snow watch from saturday evening through sunday evening for paz001>003. marine...small craft advisory until 7 pm est sunday for lez142>149. && $$ synopsis...kec near term...kec/tk short term...kec long term...kubina aviation...oudeman marine...kubina #weather - #lakeerie