Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 170431
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1231 AM EDT Tue Apr 17 2018

.SYNOPSIS...
Issued at 200 PM EDT Mon Apr 16 2018

Light snow showers or flurries will be scattered across the region
overnight. Low temperatures will be in the upper 20s to lower 30s.
Tuesday will be another chilly day with highs ranging from the
middle 30s across Lower Michigan and far northwest Ohio to the
lower and middle 40s over north central and east central Indiana.
A gradual warming trend is expected toward the weekend but
temperatures will still be below normal for middle to late April.

&&

.SHORT TERM...(This Evening through Tuesday)
Issued at 200 PM EDT Mon Apr 16 2018

Water vapor imagery depicting closed upper low over the area this
afternoon with a series of impulses rotating down the backside along
lake Michigan generating numerous snow showers over the forecast
area. Closed low will continue E/NE tonight but great lakes region
will still be under deep cyclonic flow and keep lingering chances
for snow showers over much of the area. Windy conditions this
afternoon will continue tonight in presence of strong surface
gradient. Low level thermal trof rotating down will aid in favorable
low level temperature profile to continue mixing down 25-30kt gusts
as well. Cyclonic flow finally lifts out of the area Tuesday
afternoon as weak surface ridging builds in from the west. Continued
unseasonably cold Tuesday with temps 20F below normal over most of
the area...clearing skies in SW CWA will allow for some moderation
into the low 40s while rest of the area only upper 30s to around
40.

&&

.LONG TERM...(Tuesday Night through Monday)
Issued at 200 PM EDT Mon Apr 16 2018

Weak surface ridging will provide a dry start to the forecast
period. Good radiational cooling for Tuesday night with mainly
clear skies and light winds...but strong low level thermal
response in advance of next system will temper cooling to 25-30F
for lows...but still 10-15F below normal. Pacific energy coming
onshore in the western US Monday will have longwave upper trof
axis shift from the west coast into the Rockies/high plains and
lead to closed low developing in the base of the trof. Surface low
associated with this system will lift out of the plains and track
northeast into the southern great lakes Wednesday. Despite strong
dynamics...moisture will be lacking as surface high pressure
remains anchored over the gulf of Mexico and effectively blocking
gulf return flow. Models remaining consistent in reflecting light
QPF amounts as a result. Decent WAA ahead of this system will have
temps near 60F in the southern CWA but track of surface low will
limit temps in the north to only around 50F. Lingering precip
chances Wednesday night into Thursday morning will have thermal
profiles supportive of possible mix with snow before ending.
Models trending toward an extended period of dry weather remainder
of the long term period. Next system coming onshore expected to
close off over the four corners region and become detached from
prevailing northern stream flow. This will keep it on a more
southerly track and allow Canadian high pressure to settle in over
the northern great lakes region and provide our area with a cool
but dry easterly flow. Temperatures will be seasonably cool in the
mid to upper 50s going into the weekend. Northern stream wave
coming into the Pacific northwest Saturday will induce downstream
ridging and height rises that will push eastward toward our area
and bring temps back to normal by the end of the forecast period.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday Night)
Issued at 1229 AM EDT Tue Apr 17 2018

CIGS and VIS may tend to bounce around between MVFR and low VFR
through the morning as lake enhanced snow showers (possibly mixed
with drizzle) continue in cold wnw flow. Drier air makes better
inroads mid morning and beyond with dry/VFR conditions
anticipated. Westerly gusts up to 25 knots will once again be
possible mid morning into the afternoon otherwise.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...Small Craft Advisory until 5 PM EDT this afternoon for LMZ043-
     046.

&&

$$

SYNOPSIS...Lashley
SHORT TERM...JAL
LONG TERM...JAL
AVIATION...Steinwedel


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