Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 210853
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
353 AM EST Sat Jan 21 2017

.SYNOPSIS...
Issued at 353 AM EST Sat Jan 21 2017

Near record warm temperatures are expected today with highs near 60
degrees for many locations under partly sunny skies. Mild conditions
will continue through Sunday, along with increasing chances for
light rain. A return to more seasonable conditions is expected by
the end of next week.

&&

.SHORT TERM...(Today and Tonight)
Issued at 353 AM EST Sat Jan 21 2017

Main sensible weather concern for this morning is fog. Surface warm
front currently draped over southern MI with just enough gradient
flow and warm air at the surface to yield visibilities at or above 5
miles to the south. North of the toll road, visibilities were more
variable earlier this morning but have since improved with warm
front surging north. Still some slight concern for redevelopment
around/just after sunrise (mainly for Berrien county) per latest RAP
and HRRR. Weak jet streak and corresponding marginal uptick in low
level warm/moist air advection did support some light drizzle in
that area earlier. With cloud edge inching closer, may clear out
enough to support some renewed saturation at the surface. However,
gradient wind is relatively strong and will only increase through
the morning as PV anomaly encroaches on the region and some (albeit
very limited) mixing develops in well-established warm sector.
Surface temps are also quite warm already and actually slowly rising
across the area. Given current visibilities and very low chance for
redevelopment, will go ahead and cancel dense fog advisory across
our MI counties.

Near-record warm temps will be the other big story for today. 925mb
temps climb solidly into the lower teens by this afternoon with
surface temps already in low 50s across much of the area. Upper 50s
seem virtually assured and low 60s increasingly probable. Remain
skeptical but several forecast soundings from various NWP members do
suggest we could actually clear out today, especially in our S, and
latest satellite imagery would suggest that is a possibility.
Remained on the pessimistic side with cloud forecast but did trend
toward a much less cloudy/warmer forecast, especially in our SE.
Record highs of 66F at both KSBN and KFWA (set in 1906) will be
tough to beat but may come close if we do mix out.

Removed most PoP`s for this afternoon as bulk of latest solutions
indicate next round of weak low/midlevel convergence not arriving
until around/after 00Z. Some light rain expected tonight with
passage of subtle shortwave and weak isentropic upglide but amounts
will be light and only worthy of low chance PoP. Some reduction in
static stability with exceptionally warm/moist low levels may aid
weak synoptic forcing but don`t see enough instability to warrant
any thunder mention. Overnight lows will be similarly mild, likely
holding in the mid 40s. Record high minimum temps may be in jeopardy
for both today and tomorrow.

&&

.LONG TERM...(Sunday through Friday)
Issued at 353 AM EST Sat Jan 21 2017

Main concern for Sunday and Monday will be large and impressive
closed low passing through the Tennessee Valley and into the Mid-
Atlantic. Latest deterministic runs have trended a bit further north
this cycle with GFS, NAM, and Canadian now clipping our CWA with a
fair amount of deformation-driven precip during this time. ECMWF
remains further S/SE but still manages to throw some Atlantic
moisture/precip into our eastern zones by late Monday. Confidence
remains on the low side for this time period with exact precip
timing and chances difficult to pinpoint. Don`t expect any heavy
rain but may be enough to prolong minor river flooding or at least
slow the fall. One last mild day on Sunday but thermal profiles drop
by Monday as flow backs to N/NW. Still above normal for this time of
year but backing out of record territory.

Next formidable jet streak/vort max to impact the Great Lakes on
Wed. Remains warm enough for primarily rain here with best
deformation/fgen north of our CWA but this wave does herald the
arrival of more seasonable temps and return of frozen precip for the
end of the week. Broad, cyclonic NW flow will bring periodic snow
showers by Thu/Fri with some lake contribution as 850mb temps drop
back below -10C.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday Night)
Issued at 1252 AM EST Sat Jan 21 2017

Strong northward warm sector push allowing for significantly
improved flight conditions across northern IN this morning. Small
patch of drizzle invof KSBN may result in tempo reductions next
few hours. Residual moisture within 015-020 layer could allow
reformation of stratocu layer after daybreak, otherwise trend to
VFR conditions appears to have highest likelihood of outcomes.
Guidance a bit overly bullish at this time with respect to br/fg
formation towards daybreak Sunday and this will need at least a
further review in later forecasts.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SYNOPSIS...AGD
SHORT TERM...AGD
LONG TERM...AGD
AVIATION...Murphy


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