Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 242319

Area Forecast Discussion
National Weather Service Northern Indiana
619 PM EST Wed Feb 24 2021

Issued at 349 PM EST Wed Feb 24 2021

Clouds this evening give way to some sunshine on Thursday. It will
be slightly cooler tonight through Thursday night. Friday will
mark the beginning of a warming trend, with high temperatures by
Saturday and Sunday reaching the upper 40s and lower 50s. A fast
moving system will also bring a good chance of light rain Friday


.SHORT TERM...(This Evening through Thursday)
Issued at 349 PM EST Wed Feb 24 2021

Secondary cold front is working across southern Lower Michigan and
northern Indiana this afternoon. Low level baroclinic zone with
this front is more pronounced with slowly falling temperatures
this afternoon across northeast Illinois/northwest Indiana. This
shot of cold advection will allow some stratus to work southward
into this evening in scattered-broken fashion. The primary upper
level wave will continue to dampen across the Great Lakes
tonight. Some higher res guidance does try to indicate weak lake
response and formation of weak lake aggregate troughing across
eastern half of Lake Michigan tonight, but profiles do not look
overly supportive for anything more than perhaps some prolonged
low clouds downwind of the lake with a low inversion height and
lackluster RH in DGZ. Wind gusts will ease this evening with loss
of better mixing and some weak decoupling.

On Thursday, more vigorous upper trough will dig across the Four
Corners region while progressive weak, low amplitude wave races
across central CONUS. This should offer nothing more than just some
increasing high could in the afternoon. Weaker mixing on Thursday,
lingering snowpack, and residual low level thermal trough should
make for a cooler today with highs limited to mid 30s to low 40s.


.LONG TERM...(Thursday Night through Wednesday)
Issued at 349 PM EST Wed Feb 24 2021

Deep layer subsidence continues into at least the first part of
Friday before attention turns to the next eastern Pacific jet streak
amplifying the next upstream trough. General signal of guidance has
been persistent with this feature, indicating perhaps two areas of
maximum precip chances, one area along and north of Route 6 in
closer proximity to mid/upper forcing and better fgen forcing, and
second area across the south/southeast along better low level
moisture transport axis. Low levels will be initially dry, but
strength of thermal and moisture advection should result in
primarily rain p-type late Friday night. Thermal profiles likely
will be a bit more marginal across the northwest where cannot
discount rain/snow mix for a time. Decent warm layer and
overnight northeast advance of mid level dry slot could pose some
drizzle possibility as precip rates wane late overnight/early
Saturday morning. Brief residence time of deeper moisture
profiles and good progression of this system still look supportive
of light precip amounts, and nothing that would have significant
hydro impacts with ongoing snowmelt. Did raise PoPs for Friday
night to high chance/low likely given the consistent signals in
guidance however.

Warming trend becomes established in full force for the weekend as a
positively tiled larger scale upper trough develops across western
CONUS. This will rapidly erode snowpack across the region this
weekend. While river levels will rise across the area
through early next week,  still not expecting significant hydro
impacts at this time considering the extended period this snowmelt
has occurred along with continued thawing soils and lack of any
significant additional rainfall. Highs this weekend should range
from the upper 40s to as warm as the mid 50s across areas where
snowpack is eroded more quickly.

Precip chances this weekend into early next week are of low
confidence. Background anticyclonic shear across the Upper
Midwest/Great Lakes should tend to favor a positively tilted upper
trough evolution of the western CONUS trough into early Monday. This
is turn should favor more suppressed solution for low level features
keeping bulk of precipitation south of local area. Will maintain
some low chance PoPs across southern half during this period with
some elevated frontal forcing possible in this flow regime. Temps
should cool back down into upper 30s/lower 40s early next week.


.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 613 PM EST Wed Feb 24 2021

In the wake of a cold front that has pushed through the area, an
MVFR deck has moved over KSBN and is knocking on the door of
KFWA. Confidence is medium regarding the end time of these
ceilings. The catch at KSBN could be a lake-influenced cloud deck,
prolonging MVFR conditions. However, wind from the NNW should
negate that ever so slightly (when compared to a true NW wind).
Wind will diminish overnight as the associated low moves east.
Winds become westerly tomorrow.


LM...Small Craft Advisory until 4 AM EST Thursday for LMZ043-046.



SHORT TERM...Marsili
LONG TERM...Marsili

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