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Area forecast discussion 
National Weather Service northern Indiana
336 am EDT Monday Aug 31 2015

issued at 109 am EDT Monday Aug 31 2015

Areas of fog this morning will give way to a warm and partly
cloudy Monday as highs reach the middle 80s. This warm and muggy
pattern will continue through the rest of the work week as an
upper level ridge sets up over the region. There will be some
opportunities for isolated thunderstorms each afternoon...although
expect most locations to remain dry.


Short term...(today and tonight)
issued at 334 am EDT Monday Aug 31 2015

Mainly clear skies, calm winds, and elevated surface dewpoints has
allowed widespread fog to develop northwest of a diffuse surface
trough early this morning...mainly along/northwest of the Highway 24
corridor. Given current obs, high surface-900 mb relative humidity fields, and what
occurred upstream yesterday have opted for a dense fog advisory
through 13z in these areas. Diurnal mix out/up to a scattered-broken cumulus
field is then expected middle morning into early afternoon.

Building heat/instability for the afternoon may allow a few pop up
storms to fire amid the aforementioned weak surface trough...located on
the northern fringe of leftover weakness in the middle/upper level
height field. This favors areas mainly southeast of the Highway 24 corridor in
Indiana and Ohio for a mentionable low pop. Dry/warm otherwise with
fog possibly a concern once again later tonight in the same areas.


Long term...(tuesday through sunday)
issued at 334 am EDT Monday Aug 31 2015

Previous forecast appears to be in good shape for the long term
period with main forecast themes centering on increased heat...and
diurnally enhanced potential of isolated showers/storms.

For Tuesday/Tuesday night main feature of interest will be residual
vorticity maximum from system which sheared out over the local area
yesterday. Water vapor imagery morning depicting some discernible
upper level circulation with this feature...and could be enough
forcing for isolated showers/storms mainly during peak heating on
Tuesday. Despite low level warm air advection beginning to ramp up in the
afternoon...effects from warm air advection induced clouds/DPVA associated with
vorticity maximum should limit highs to the lower to middle 80s for most
locations. Have kept Tuesday night dry at this time but some
possibility may exist for isolated shower development due to
combination of meandering vorticity maximum and some isentropic ascent
associated with departing cool pocket. Wednesday probability of precipitation may be a bit
more questionable with consensus of latest deterministic guidance
tending to drift this vorticity maximum southeast of the area. Hesitant to
pull isolated probability of precipitation for Wednesday however given broad isentropic ascent
coupled with diurnal no major changes made to
previous forecast. Bigger story for the middle week period will be
the transition to above normal temperatures...with expected better
insolation on Wednesday and warm air advection allowing highs to reach into the
upper 80s most locations.

For Thursday and Friday it still appears as though very weak Pacific
origin waves may try to progress through building upper level
ridging across the region. However...will keep forecast dry at this
time given weak nature of forcing and the likely more questionable
surface based instability by this timeframe. Warm conditions to continue
through the weekend...although building anticyclone across southeast
Canada/northeast Continental U.S. Should tend to allow northeast low level flow
to evolve across the region keeping temperatures in check into middle 80s. The
next chance of mentionable precipitation should hold off until after this
forecast period with the potential of a more significant upper
trough moving across north central Continental U.S..


Aviation...(for the 06z tafs through 06z Monday night)
issued at 109 am EDT Monday Aug 31 2015

Light winds, residual near surface moisture, and mainly clear
skies already allowing LIFR fog to fill in just north-northwest of kfwa and
all around ksbn. See no reason why fog doesn't fill in at each
terminal early this morning...although some question remains on
whether 15 knots flow at 925 mb provides enough mixing to keep this a
stratus/fog mix instead of widespread quarter mile or less
visibilities. Conditions should rapidly improve after 14z with VFR
conditions and light SW winds anticipated by early-middle afternoon.


Iwx watches/warnings/advisories...
in...dense fog advisory until 9 am EDT /8 am CDT/ this morning for

Michigan...dense fog advisory until 9 am EDT this morning for miz077>081.

Ohio...dense fog advisory until 9 am EDT this morning for ohz001-002-



short term...steinwedel
long term...marsili

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