Area forecast discussion
National Weather Service northern Indiana
653 am EDT Friday may 24 2013
Synopsis...
issued at 322 am EDT Thursday may 23 2013
High pressure will continue to build southeast from Canada across
the Great Lakes and Ohio Valley today and tonight... causing fair
weather across the region... with unseasonably cool temperatures.
&&
Short term...(today and tonight)
issued at 322 am EDT Friday may 24 2013
Cool high pressure over the upper Great Lakes will move very slowly east-southeast
through this period as low pressure closes off and deepens along the
New England coast. Extensive Post frontal strato cumulus deck was moving
slowly south but still lingering over southeast 1/2 of the County Warning Area at 07z
with some new development over Northwest Indiana and Southeast Michigan downwind of
Lake Huron. Expect some cloud cover will linger over mainly southeast
portion of County Warning Area past dawn... but subsidence/drying should continue
diminishing cloud cover trend with sunny skies most of the day.
Combination of low level thermal trough moving east of the County Warning Area today
along with nearly full sunshine should result in a decent warmup.
Little change made to previous forecast with highs still expected to
exceed consensus MOS by a few degrees.
Shortwave lifting NE into the northern plains today/tonight should result in
some thunderstorms developing at nose of low level jet which will advect east-southeast toward
the Great Lakes/Ohio Valley. Convection not expected to reach our
area... but some cirrus from the upstream convection will likely
overspread the County Warning Area tonight. This should limit temperature drop in
our County Warning Area despite a dry airmass and light winds. Leaned toward
warmer guidance with lows forecast well below normal in the u30s/l40s.
&&
Long term...(saturday through thursday)
issued at 322 am EDT Friday may 24 2013
Tranquil weather expected for the bulk of this forecast period as
expansive longwave ridge builds over the Great Lakes. Precipitation chances
will depend on rather vexing small-scale vorticity maxima rotating
through the eastern edge of this ridge over the weekend and the
eventual passage of a low level warm front early next week. Latest
00z NCEP models continue to be awfully bullish in the eastward push
of low level Theta-E advection compared to their ec and Gem
counterparts. NAM and GFS seem to be suffering from convective
feedback issues associated with thunderstorms firing on the nose of
a 35kt low level jet over the Central Plains. The downstream propagation of
these convectively induced waves is generating pockets of quantitative precipitation forecast for
our County Warning Area Saturday and Sunday. Remain very skeptical of this idea and
still prefer the drier European model (ecmwf)/Gem solution. Steering layer flow looks
to keep convection southwest of our County Warning Area and strength of ridging
aloft combined with overall blocky nature of hemispheric pattern
favors a slower eastward progression of the low level baroclinic
zone. Warm front will eventually make its way east but showers
should hold off until at least Monday. By that point...Pacific jet
energy should force some eastern progression of stubborn central
Continental U.S. Ridge while pieces of the western Continental U.S. Trough eject northeast
and attempt to dampen the ridge somewhat. Current thinking is
Tuesday will be the best chance for precipitation but will likely be fairly
scattered given lack of any good upper level support. Midlevel ridge
looks to expand again by midweek with southern Great Lakes in a
strongly capped and dry warm sector.
As for temperatures...lack of any strong thermal advections will
lead to temperatures on Sat and sun that are very similar to those expected
today. Increasing clouds will likely offset the gradual moderation
of ambient airmass and highs in the middle to upper 60s still look good
based on latest guidance. Increasingly limited radiative losses will
result in overnight lows a touch warmer...generally middle to upper
40s. Monday will be a bit of a transitional day before warm front
lifts northeast on Tuesday. Good southwest flow/warm air advection and dry
subsident airmass should allow for temperatures well into the 80s by
midweek. Continued earlier noted trend of upward adjustment to
consensus blends based on 850mb temperatures approaching the upper teens
once again.
&&
Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 649 am EDT Friday may 24 2013
Back edge of Post frontal strato cumulus moving through FWA early this
morning with just patchy low clouds upstream. Low levels will
continue to dry out today as high pressure builds in... so little
if any diurnal cumulus expected. Cirrus over the northern plains/rockies
will move southeast in northwest flow aloft and probably be enhanced tonight by
convective development at the nose of the low level jet over the
northern plains/upper Midwest... these high clouds should overspread northern
Indiana tonight. Light northerly winds expected across northern
Indiana today as ridge axis remains west of the area. Winds should
become nearly calm tonight as the high pressure center moves
slowly through the area.
&&
Iwx watches/warnings/advisories...
in...beach hazards statement through this evening for inz003.
Michigan...Beach hazards statement through this evening for miz077.
Ohio...none.
Lm...Small Craft Advisory until 3 PM EDT this afternoon for lmz043-
046.
&&
$$
Synopsis...jt
short term...jt
long term...agd
aviation...jt
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