Area Forecast Discussion
Issued by NWS Indianapolis, IN

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121
FXUS63 KIND 211455
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
955 AM EST Sun Jan 21 2018

.UPDATE...
The NEAR TERM Section has been updated below.

&&

.SYNOPSIS...
Issued at 325 AM EST Sun Jan 21 2018

Low pressure developing over the central plains will move to the
great lakes by Monday night and up the St. Lawrence valley Tuesday
and Wednesday.  A trailing cold front will push east across our area
late Monday.

Temperatures will continue to warm today into early Tuesday and then
become cooler by Tuesday.

An area of high pressure will move east across the Ohio valley by
Thursday.  Another area of low pressure will bring rain showers and
mild temperatures our way by Saturday.

&&

.NEAR TERM /This afternoon/...

Issued at 955 AM EST Sun Jan 21 2018

Surface analysis late this morning shows low pressure over Kansas
with a warm front extending northeast all the way to northern
central Indiana...laid across LAF and OKK. Visibilities and Fog
remained very low along and north of the warm front. GOES16 shows
extensive cloud cover across Central Indiana...much of which was
within the warm sector. However it should be noted that
visibilities were better on the south of the front.

Models suggest warm air advection to continue through the day and
lower level moisture remains predominate within the Time heights
and forecast soundings....with dry air aloft and weak lift in
place. This is the classic recipe for fog and drizzle. Thus will
continue to keep the fog and drizzle aspect to the forecast
through the afternoon. Some daytime mixing and an expected
northern lift of the warm front may allow the dense fog advisory
to be ended at noon...but we will wait a couple of hours before
crossing that bridge.

&&

.SHORT TERM /Tomorrow through Tuesday Night/...
Issued at 325 AM EST Sun Jan 21 2018

Strong low pressure will move across the upper midwest into the
Great lakes Monday.   A trailing cold front will push east across
Indiana Monday.  Models indicate number showers will occur and there
may be just enough instability to mention isolated thunder over
western sections Monday morning.

The low pressure system will move east across the great lakes
Monday night and a cold front extending south across Indiana will
move east.  An upper low over northern Illinois will produce numerous
light showers over northern sections and scattered showers in the
south.   Model soundings and BUFKIT indicate a change over to snow
showers by daybreak Tuesday.

Tuesday...will be much cooler with scattered light snow showers.
The ground should be fairly warm which should limit accumulations.
However far northern sections could see up to a half inch Tuesday.

Cut daytime temperatures slightly Tuesday with strong cold advection.

Only other change was to increase wind speeds Monday into Tuesday
as models indicate a fairly strong pressure gradient. In most cases
used CONSALL winds instead of Superblend.

&&

.LONG TERM /Wednesday through Saturday/...

Issued at 251 AM EST Sun Jan 21 2018

As has been the case the past few days, the main storm track has
shifted to more of a west-to-east across the CONUS. This has
moderated temperatures and it looks like, for the most part, this
will be the case through this period.

Wednesday will start off with a mid/upper level trough effecting
the earlier periods moving off to the east and high pressure
centered over the mid/southern Plains moving eastward into the
Tennessee Valley to the south. This will result in a dry period
through Thursday with temperatures around normal for Wednesday,
then warming to the mid-upper 40s during the day as the high moves
off to the east.

A minor wave at mid levels is forecast by the models to move
northeast through the area going into Friday, but no precipitation
is expected at this time. As this feature minors out Friday
afternoon, the next mid/upper level trough will move in for the
later periods with warm air advection ahead of the accompanying
frontal boundary late Friday/early Saturday. As with the frontal
boundary earlier in the week, this next cold front will result in
widespread rain and possibly isolated thunderstorm with it as it
enters the state Saturday afternoon. High temperatures on Friday
and Saturday will be well above normal with 50s in the southern
half of our area and low temperatures in the low-mid 30s Friday
and in the 40s going into Saturday.

&&

.AVIATION /Discussion for 211200z TAF Issuance/...
Issued at 618 AM EST Sun Jan 21 2018

MVFR flight conditions southern sections and IFR or LIFR elsewhere.

Low pressure over the central plains was producing a light to
moderate southerly flow across the area.   Moist air clashing with a
cold ground and melting snow was producing areas of fog/stratus with
the lowest conditions occurring over northern sections.

Should be little change today with some slow improvement tonight
as winds increase.  Marginal low level wind shear at KBMG today and
at all sites tonight.    Surface winds will be south 5 to 7 knots
today increasing to 10 to 15 knots Monday morning.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until noon EST today for INZ021-028>031-
035>041-043-044.

&&

$$

SYNOPSIS...JH
NEAR TERM...Puma
SHORT TERM...JH
LONG TERM....DM
AVIATION...JH



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