Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 201135

Area Forecast Discussion
National Weather Service Northern Indiana
635 AM EST Mon Feb 20 2017

Issued at 454 AM EST Mon Feb 20 2017

High pressure moving away from the area today will continue to
provide us with fair weather. Some morning fog is
expected,especially over southern portions of the area, but the
afternoon should be mostly sunny and unseasonably warm. A weak
cold front will cause showers as it moves across the area tonight
and Tuesday. Dry and warm weather is expected Wednesday ahead of
another weak cold front. This front will drop into the area
Thursday, possibly causing showers. A strong low pressure system
will move northeast across the western Great Lakes Friday and to
southeast Canada on Saturday resulting in showers and possibly
thunderstorms in our area Thursday night and Friday, followed by
colder temperatures and a chance of snow showers Saturday.


.SHORT TERM...(Today and Tonight)
Issued at 454 AM EST Mon Feb 20 2017

Dense fog over central IN/OH has been spreading slowly north early
this morning into an area which received good radiational cooling
earlier, and now is undergoing weak moisture advection on backside
of departing ridge. Expect this dense fog will impact at least our
srn counties before diurnal heating mixes it out later this
morning. Issued a dense fog advisory for this area based on
upstream obs and latest HRRR vsby fcsts. By afternoon, expecting
mostly sunny skies and soaring temps once again as a strong upper
level ridge moves across the area. Mixing heights should be
enhanced today by a stronger s-se pressure gradient. This should
allow temps to climb well into the 60s over most of the area again

Upper trof and accompanying sfc cdfnt movg into the Plains this
morning will weaken as it moves east tonight and Tuesday, but
still should be accompanied by sufficient moisture/forcing to
produce a band of showers as it moves across our area. Models have
come into better agreement on the timing of this trough passage
with the faster GFS slowing down toward earlier ECMWF/NAM
solutions. Thus, lowered pops tonight, especially across the sern
portion of the cwa. Gradient mixing and clouds combined with the
very warm airmass in place will keep temps from falling much
tonight, though evaporational cooling as showers move in should
cool off the nw over what would otherwise occur. Records for
highest minimum temperatures at SBN and FWA (45F in both
locations) should be broken tonight with lows ranging from the mid
40s ne to the mid 50s sw (around 50F at SBN/FWA).


.LONG TERM...(Tuesday through Sunday)
Issued at 454 AM EST Mon Feb 20 2017

Showers along the cdfnt Tue should mainly move east of the area
by early aftn. With only wk CAA behind the front and a very mild
start to the day, temps should be able to climb into the lower to
middle 60s once again. Shrtwv movg east from the nrn Plains to the
upr Grtlks on Wed will result in a very warm airmass movg into our
area with H85 temps climbing to >12C. Fairly strong low level
pressure gradient along with sunny skies should result in record
highs in the upper 60s to lower 70s. Cdfnt associated with this
shrtwv is expected to drop into our area Wed ngt psbly accompanied
by a few showers. Front will stall out in our area Thu as a strong
low develops over KS. This system will lift ne to near Lake
Michigan on Friday. As it approaches the stalled front over our
area will transition to a warm front and lift north Thursday night
resulting in showers and possibly thunderstorms as weak
instability and steep mid level lapse rates overspread the area.
As the low passes by to our north on Friday the cold front will
sweep across the area providing showers and psbly thunderstorms.
Strong wind fields in a high shear/low CAPE environment may result
in a squall line movg through the area with damaging wind
potential. Northwest flow in the wake of the low will bring  much
colder air and the potential for snow showers on Saturday. High
pressure will move across the area Sunday providing generally fair
weather, hwvr, some light snow is psbl over wrn portions of the
CWA in the aftn as WAA develops behind the retreating high.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning)
Issued at 635 AM EST Mon Feb 20 2017

Another difficult aviation forecast with KFWA right on the edge of
better near-surface moisture and fog. Latest hi-res guidance still
shows saturation in the 12-15Z timeframe but confidence is low
given that dewpoint depression is still 5 degrees and sun is
rising. Left in fuel alternate TEMPO group but could easily
remain VFR. No fog/BR expected at KSBN given 12 degree dewpoint
depression there. Otherwise, VFR expected at both terminals
through the evening. Front approaches the area Tuesday morning
with increasing chances for rain and MVFR conditions. However,
most impacts will likely be 09Z or later.


IN...Dense Fog Advisory until 9 AM EST /8 AM CST/ this morning for

OH...Dense Fog Advisory until 9 AM EST this morning for OHZ024-025.

LM...Small Craft Advisory from 4 PM this afternoon to 4 AM EST
     Tuesday for LMZ043-046.




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