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fxus63 kiwx 281935 

Area forecast discussion
National Weather Service northern Indiana
335 PM EDT Wed Jun 28 2017

issued at 335 PM EDT Wed Jun 28 2017

A few light showers and storms are possible across Northwest Indiana
and southwest Michigan tonight but a much better chance of rain is
expected Thursday evening and Friday. Some of these storms may be
severe with damaging winds and heavy rain possible. Drier and less
humid conditions are anticipated over the weekend.


Short term...(this evening through Thursday night)
issued at 335 PM EDT Wed Jun 28 2017

Impressive shortwave entering the western lakes starting to dampen
and lift more east-northeast amid general longwave ridge building. Healthy
low level jet/Theta-E surge ahead of this wave but best moisture flux
convergence focused generally northwest of our area with models indicating
a relative Theta-E sink across in and Ohio through the evening.
Earlier convection tried to make a run at our western County Warning Area but
withered quickly as it divorced from better convergence and
associated moisture/instability plume. A few decaying showers in our
far northwest but by and large expect dry conditions through the evening.
Another chance for rain will arrive in our northwest after 06z tonight. Low level jet
continues to veer and support a little better moisture in our N/NW.
Another round of decaying showers/storms possible along remnant
convergent boundary. However, moisture quality still somewhat
questionable with limited MUCAPE and lack of coherent forcing with
increasingly diffuse boundary. Maintained some low chances in north
but made further cuts based on latest hi-res cam's and underlying
setup. No severe threat.

Better chances for storms, potentially severe, arrive late Thursday.
Next shortwave approaches by that time with old stationary boundary
draped generally along the I-80/90 corridor and ample moisture
streaming into the region in SW flow. The synoptic picture is a
little muddled with persistent convection upstream ejecting multiple
shortwaves into our area. Assuming morning convection dissipates as
expected, tomorrow will be largely dry during the day with enough
sun (and more importantly, rising surface dewpoints) to generate
around 2k j/kg of SBCAPE. 70f dewpoints seen in raw guidance quite
possible given support from MOS guidance. Wind/shear profiles also
supportive of severe weather with 850mb flow of 30+ kts and 0-6km
shear values around 30 kts. Wind/shear profiles oriented generally
parallel to the front, indicating some bowing segments with damaging
winds possible if more sustained updraft develops. Isolated heavy
rain/flooding also a concern given orientation of the front,
potential for training, relatively low mbe velocities, and precipitable water values
around 1.75 inches. However, confidence is still not high on
severe/flooding threat. Best chances don't arrive until late (after
21z and potentially as late as 03-06z when diurnal instability is
waning) and there is a weak cap noted in both GFS and NAM soundings
around 750mb. Forcing is also a bit dubious, predicated on
convectively enhanced wave ejecting out of the High Plains with
otherwise fairly broad convergence. Track of any potential organized
convective system also uncertain with higher resolution models
offering disparate solutions regarding the finer-scale details.


Long term...(friday through wednesday)
issued at 335 PM EDT Wed Jun 28 2017

Friday expected to be equally, if not more, busy. Main longwave
trough inches closer with another convective shortwave ejecting into
our area. Moisture quality remains high and could see another 2k
j/kg of SBCAPE by late afternoon with healthy wind/shear profiles.
Problem is that uncertainty with regard to Thursday night leads to
compounding uncertainty for Friday. Some solutions suggest
rain/clouds may persist through Friday morning with limited
opportunity to recover. Others suggest dry conditions during the day
with ample destabilization and healthy line of convection during the
evening. Lean toward the latter solution given approaching
trough/better synoptic forcing signal but will have to get through
Thursday first before anything definitive can be said. If severe
weather does occur, looks like it would be in the 21-03z period with
damaging winds the main threat.

A few (non-severe) showers and storms may persist into Saturday,
especially in our east but expect a gradual drying trend as broad
trough axis passes and northwest flow/negative Theta-E advection slowly
ramp up. Highs will still be near 80f but do expect a significant
drop in dewpoints that will make it feel cooler. Chances for
showers/storms return around the 3rd-4th as moisture plume creeps
back north and multiple shortwaves approach. Still much too early to
nail down any timing details though.


Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 1238 PM EDT Wed Jun 28 2017

An area of showers and isolated storms over northeast Illinois is
expected to weaken this afternoon. There is a better chance for a
storm late tonight as a weak upper level disturbance approaches.
Mentioned thunderstorms in the vicinity at sbn 09-12z; otherwise, no significant weather
is expected.


Iwx watches/warnings/advisories...
Michigan...Beach hazards statement through Thursday afternoon for miz077.

Lm...Small Craft Advisory until 2 PM EDT Thursday for lmz043-046.



short term...agd
long term...agd

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