• synopsis
• near term
• original discussion
• short term
• long term
• aviation
• marine
• hydrology

Area Forecast Discussion - Apr 10, 2013 0743

national weather service cleveland oh
734 am edt wed apr 10 2013

Includes Toledo area.

synopsis

a frontal boundary will oscillate across the area today and
tonight. a strong low pressure system will move across the area
late thursday.

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.

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.

&&

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.

&&

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.

&&

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.

&&

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.

&&

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

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