Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 181435
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
935 AM EST Sat Jan 18 2020

.UPDATE...
The NEAR TERM and AVIATION sections have been updated below.

&&

.SYNOPSIS...
Issued at 252 AM EST Sat Jan 18 2020

Precipitation will continue throughout the morning, primarily as
rain. Following the passage of a cold front Saturday evening,
temperatures will plummet and remain cold through early next week.
Dry conditions are expected for most of next week, before another
chance of precipitation late next week into next weekend.

&&

.NEAR TERM /Rest of Today/...
Issued at 935 AM EST Sat Jan 18 2020

Forecast is in pretty good shape. Rain continues across central
Indiana with temperatures in the mid 30s to mid 40s. Adjusted hourly
PoPs a bit, but diminishing trend into this afternoon from west to
east still looks good.

Tweaked temperatures a bit as needed. Upped wind gusts based on
latest trends and model data.

Previous discussion follows...

Surface analysis early this morning shows deep low pressure in place
over eastern KS and NE. A warm front extended east from the low
across MO...to Western KY and then to SW Virginia. Water vapor
showed a plume of tropical moisture streaming across TX and
Arkansas to Illinois and the Great Lakes. National Radar Mosaics
shows extensive precip within the plume over Illinois and eastern
MO...poised to stream into Indiana later today.

Models suggest the surface low over the plains will push northeast
toward the Great Lakes...dragging the surface warm front to the
south across Indiana this morning...Models show ongoing Warm air
advection through mid day as the warm front arrives. Forecast
soundings remain saturated through at least 18Z...also showing that
warming trend and moving above freezing within a large part of the
lower levels of the column. Models also shows the upper trough axis
pushing across the state by 18Z. Good isentropic lift remains in
place ahead of this axis within the warm sector...but as this
feature passes...subsidence...drying and cold air advection begins
to take over...which should bring precip to an end. Fortunately,
temperatures look to be well above freezing through mid-day while
precip is falling...thus as the warm front passes this
morning...precip will change to rain and remain rain for the rest if
this event.

Thus with many favorable features in play for precip today will
trend pops toward 100. Given the warm air advection...will expect
highs in the early afternoon before frontal passing. Will trend
highs at or below the NBM.

&&

.SHORT TERM /Tonight through Monday Night/...
Issued at 252 AM EST Sat Jan 18 2020

Near the beginning of the short term, temperatures will quickly drop
following the passage of a strong cold front. Temperature drops of
near 20 degrees are possible over a few hours with overnight lows
in the low teens. Untreated wet roads may freeze as temperatures
drop, creating slick conditions. A low level cloud deck should
remain with upper level subsidence suppressing the the relatively
moist boundary layer. Breezy conditions are likely overnight,
expect sustained winds between 15 and 20 mph.

High pressure will continue to build into central Indiana throughout
Sunday in the presence of strong low level cold air advection.
Temperatures will increase slightly with daytime heating, but the
strong northwest flow and CAA will stifle warming at the surface.
With this in mind, expect high temperatures on Sunday afternoon to
be in the upper teens. Sustained winds around 12 to 15 mph will
cause wind chill values to be near to below 0 on Sunday morning.

Cold conditions will remain Monday morning, as the bitter
northwest flow dominates. However, a weak upper level wave will
progress near Indiana throughout the day. This should allow for a
few breaks in the cloud layer and diminished NW flow, leading to
slightly warmer daytime highs. A strong surface ridge will limit
moisture and any chance for precipitation in central Indiana.

&&

.LONG TERM /Tuesday through Friday/...
Issued at 241 AM EST Sat Jan 18 2020

Strong Canadian high pressure will be the primary feature
influencing weather pattern through midweek across the region with
a cold dry airmass across the Ohio Valley. As the high shifts east
during the second half of next week...ridging aloft will develop
with temperatures warming back to above normal levels in the 40s
by Thursday and Friday.

Model differences exist at this early stage with the handling of
the next storm system poised to impact the region late next week
into next weekend. Op GFS is the primary model hinting at a more
phased regime aloft supportive of a deeper surface wave over the
Ohio Valley while the ensembles and other long range models keep a
less phased...more progressive look to the system. Have deviated
little from the blend at this point with still plenty of details
to be ironed out...but will introduce precip chances Thursday
night and Friday likely continuing into the first half of next
weekend. Potential exists for a wintry mix at times but in
general...this system is likely to produce rain as the primary
precip type.

&&

.AVIATION /Discussion for 181500Z TAF Update/...
Issued at 355 AM EST Sat Jan 18 2020

Brief VFR ceilings will not last with MVFR and IFR on KIND`s
doorstep. Adjusted timing a bit but still let IFR return within a
couple of hours.

Previous discussion follows...

Poor flying conditions will continue throughout much of the
forecast period.

Surface temperatures have now warmed above freezing at all
terminals early this morning with rain as the precipitation type.
Rain will continue through early afternoon prior to the passage of
a strong cold front. Winds will be primarily from the south ahead
of the boundary this morning before veering rapidly to a W/SW
direction once the front passes. Low level wind shear will remain
an issue at all terminals through midday.

In wake of the frontal passage early this afternoon...winds will
become gusty from the W/SW and eventually by late afternoon into
tonight from the west. Peak gusts of 30-35kts will be possible
late this afternoon through tonight. IFR ceilings by early this
afternoon will gradually lift to between 1000-1500ft and hold
through much of tonight as a shallow inversion lingers. Any
substantial scouring of the stratus deck will likely hold off
until Sunday.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SYNOPSIS...Updike
NEAR TERM...Puma/50
SHORT TERM...Updike
LONG TERM....Ryan
AVIATION...Ryan/50


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