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Area forecast discussion 
National Weather Service northern Indiana
415 PM EDT Monday may 25 2015

issued at 410 PM EDT Monday may 25 2015

Winds will die down and rain showers will diminish later this
evening. Skies tonight will be partly to mostly cloudy and lows
will be in the 60s. An area of low pressure will bring showers and
thunderstorms to the area Tuesday. Highs will range from the middle
70s to the low 80s.


Short term...(this evening through tuesday)
issued at 338 PM EDT Monday may 25 2015

Dry slot associated with vorticity maximum currently lifting into the
northern Great Lakes is bringing an end to scattered showers from west
to east as planned. Main story this afternoon has been gusty winds
with planetary boundary layer mixing just deep enough to mix down some gusts around 35
kts...aided in some spots by line of convective showers. Low level jet is
gradually weakening this afternoon though as parent wave lifts
northeast and gradient relaxes. Latest surface observation indicate a
slight downward trend in ambient wind gusts and expect that trend
to continue and accelerate into the evening hours. Subtle
shortwave ridging and loss of deeper moisture will keep conditions
dry overnight. Partial clearing expected but steady southwest wind
and increasing clouds toward daybreak should keep overnight lows
generally in the middle 60s.

Another round of showers and thunderstorms is expected tomorrow as
formidable shortwave currently over the Southern Plains lifts
northeast. Wave will be increasingly sheared as it moves through the
western Great Lakes and best cva does pass just to our northwest but
should be enough forced ascent to touch off fairly widespread
convection. This is especially true given expectation for another
surge in low level Theta-E with increasing low level jet. Modest
destabilization will also occur with increasing low level moisture
and diurnal heating. Most of latest guidance shows at least scattered
convection with the best chances beginning around noon and
continuing through the evening. Inherited likely probability of precipitation seem
appropriate and only minor changes made to add some temporal detail.
Severe weather risk remains low. 0-6km bulk shear values are around
30 kts which is marginally supportive of organized convection but
poor midlevel lapse rates limit 0-1km MLCAPE values to around 1000
j/kg or less. A few strong storms may certainly be possible but
widespread severe weather is not expected at this time.


Long term...(tuesday night through monday)
issued at 338 PM EDT Monday may 25 2015

Shearing middle level shortwave lifting northeast through the
western/northern lakes will force a weak/trailing surface boundary
through the area Wednesday into Wednesday evening. Models in good
agreement in shunting deeper moisture east of the area by this
time...but with some partial clearing and boundary layer
heating/destabilization would expect scattered convection to develop in vicinity of
this feature by Wednesday afternoon (best chances southern/eastern
zones removed from stable Lake Michigan push).

Weak anticyclonic flow/shortwave ridging will promote a period of
fair weather later Wednesday night through Friday morning. Little in the
way of thermal advection combined with ample sunshine will support a
mild Thursday...although diurnal ranges will be a little greater
given infiltration of slightly drier air. Later Friday into the
weekend will feature renewed shower/storm chances as a strong
northern stream pv anomaly tracking through southeast Canada forces an
active baroclinic zone south into the local area...with moisture
convergence/advection enhanced in advance of an approaching plains
upper wave.


Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 120 PM EDT Monday may 25 2015

Conditions will continue to hover in low end VFR category through
the late afternoon as a shortwave lifts across the region. A few
scattered showers associated with this feature are also currently moving
across northern Indiana. These showers will exit during the next
1-2 hours but upstream observation still show sporadic MVFR stratocu
through western Illinois. This low level moisture will likely not
scatter out until later this evening. Mainly VFR conditions
expected overnight but next wave will be quickly approaching.
Increasing low level moisture and boundary layer cooling could
lead to some fuel alternate stratus by early tomorrow morning per
latest GFS and NAM forecast soundings/MOS guidance. Will hold with
high end MVFR for now and let later shifts adjust as necessary.
Showers and thunderstorms also possible by the very end of this
taf period.


Iwx watches/warnings/advisories...
Michigan...Beach hazards statement until 8 PM EDT this evening for miz077.

Lm...Small Craft Advisory until 8 PM EDT this evening for lmz043-046.



Synopsis...mesoscale discussion
short term...agd
long term...steinwedel

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