Area Forecast Discussion - Apr 10, 2013 0743 national weather service cleveland oh 734 am edt wed apr 10 2013 Includes Toledo area. h2. synopsis a frontal boundary will oscillate across the area today and tonight. a strong low pressure system will move across the area late thursday. h2. near term .near term /until 6 pm this evening/... front has not moved much last couple of hours. left likely pops for this morning north of the boundary as still expect an increase in activity now moving across northern indiana toward sunrise for a few hours. h2. original discussion frontal boundary is south of a meadville to findlay line. temp forecast will be difficult this morning as strong gradient across the front. temps at cle currently 45 while wooster is 20 degrees warmer with 65. models in agreement with the front continuing to oscillating across the area today into tonight. however precise timing of the boundary still in question. as far as precip goes...totally rejected the gfs. judging from the 6 hour observed rainfall gfs may be suffering from convective feedback. nam seems much more reasonable today. expect some showers across the north early this morning...then a break with widespread showers and thunderstorms developing during the afternoon. capes push above 1000 j/kg this afternoon south of the front and convection will be aided by a low level jet max moving across the area. spc has the area south of yng to fdy in a slight risk for this afternoon and evening. && h2. short term .short term /6 pm this evening through saturday night/... another wave of showers and thunderstorms will move along the boundary overnight...but models not in good agreement exactly where the boundary will set up overnight. models are in reasonable agreement moving strong low pressure currently mid mississippi valley across the area late thursday into thursday night. expect widespread thunderstorm activity as the low moves across the area. see the hydro discussion for details about the flooding threat. much colder air returns to the area for the weekend. the 850mb temps dip to minus 8c by saturday morning. && h2. long term .long term /sunday through tuesday/... the surface high should build in by saturday night with ridging on sunday. temps should recover to near normal on sunday. the pattern for early next week hints at something similar to this week...with low pressure eventually coming out of the plains states and a boundary developing across the lower great lakes. it looks like we should get into the warm sector monday into tuesday with temperatures warming into the 60s. the gfs brings a wave from the west quickly on monday while the ecmwf is slower. will compromise with the timing and stay near continuity with a slowly increasing chance of showers and eventually some thunderstorms monday into tuesday. && h2. aviation .aviation /12z wednesday through sunday/... the front will remain within a county or two of the south shore of lake erie with mvfr and ifr ceilings north of the front. additional showers and storms will spread in from the west by this afternoon...essentially developing into a weak wave on the front and pushing it farther south with a wind shift at inland sites. ceilings will drop to ifr at all taf sites by late afternoon or early evening. rain and showers will likely persist tonight across extreme northern ohio...lake erie and northwest pennsylvania. thunder could occur at just about anytime today and tonight but tried to forecast it in the taf only at the time it is most likely this afternoon. .outlook...non-vfr continuing into saturday. && h2. marine the northeast wind is already established on the lake. the gradient will come and go today as each batch of showers and thunderstorms passes by which could produce locally higher winds and waves. the main concern is more for late afternoon and evening as the northeast gradient tightens as low pressure from the mississippi valley tracks east. will post the small craft advisory starting at 4 pm to give some cushion since there will more showers and storms moving across the lake by late afternoon. not sure when we will be able to take the small craft advisory down. the surface low will pass near the lake thursday night. the west flow behind the lake may require a small craft advisory on friday but will let it end thursday night for the time being. the west flow will become northwest this weekend. high pressure should build in on saturday and the winds should begin to calm down...especially by saturday evening. && h2. hydrology concerns for flooding from late tonight thru friday. overnight the frontal boundary to our north is projected to sink back into northern ohio. meanwhile the strong storm system over the rockies will begin tracking towards the plains overnight...and a broad area of 40-50kt 850mb winds will move into the ohio valley. this jet will intersect with the front and advect warm/moist air from the gulf. precipitable water values will jump to around 1.35" which is in the 99th percentile for this time of year. this unusually moist airmass could produce heavy rain in any thunderstorm development. overnight the gfs and nam suggest a weak wave along the frontal boundary over n oh/ nw pa which could be such a catalyst. the frontal boundary will be meandering in/near the region until the upper trof swings through fri. will focus attention on the quasi-stationary front as it can support convection over the same area for a long duration. rainfall rates could be upwards of 1.5" in 3 hrs which is enough to produce flooding this time of year. some factors that could help slow/reduce the flooding is the dry winter and the onset of growing season. however these factors could be quickly overwhelmed if rainfall rates are high enough. at the time of this issuance the highest rainfall amounts are expected to occur over northern ohio notably in the maumee river basin. cannot rule out isolated areas of 2 to 3 inches of rain before the work week is out. && .cle watches/warnings/advisories... oh...none. pa...none. marine...small craft advisory from 4 pm this afternoon to 4 am edt friday for lez #weather