Area Forecast Discussion
Issued by NWS Indianapolis, IN

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FXUS63 KIND 190758

Area Forecast Discussion
National Weather Service Indianapolis IN
358 AM EDT Thu Apr 19 2018

The LONG TERM Section has been updated below.


Issued at 128 AM EDT Thu Apr 19 2018

Low Pressure will exit Central Indiana this morning...taking some
morning clouds with it. A Large high pressure system over the
plains states is then expected to build across Indiana and the
Ohio Valley the afternoon. This will bring dry weather with slowly
warming temperatures through the weekend.

The next best chance for rain will be be early next week as a low
pressure system moves through the Tennessee River Valley.


.NEAR TERM /Today/...

Issued at 128 AM EDT Thu Apr 19 2018

Surface analysis early this morning shows low pressure in place
across the Virginias. A strong area of high pressure was found
across the Dakotas...resulting in a cold northerly surface flow
for Indiana. GOES16 shows abundant cloud cover across Indiana in
the wake of the low. A secondary weak trough was found across
northern Indiana and southern Wisconsin...pivoting around the low.
Radar shows some snow showers ahead of the trough over NE IL and
NRN Indiana. Water Vapor shows a upper low near Chicago...pushing
SE toward Central Indiana.

GFS and NAM quickly push the trough axis to the north across
Central Indiana through 15Z. Time heights and forecast soundings
indicate saturated lower levels as the strato-cu passes over the
next 10 hours. HRRR also spreads light precip across northern
parts of the forecast area this morning as this feature passes.
Moisture remains limited and any precipitation amounts will be
light. Will include low pops...mainly across the northern parts of
the forecast area this morning.

The GFS and NAM push the upper low east of Indiana by 18Z and
strong subsidence begins within the column. Forecast soundings and
time height dry out...which should lead to partly cloudy skies.
Will stick close to a blend on Highs.


.SHORT TERM /Tonight through Saturday Night/...

Issued at 128 AM EDT Thu Apr 19 2018

Overall quiet weather will be expected this period.

Low temperatures tonight will likely result in values below
freezing...and a freeze warning will be needed in southern Central
Indiana where the growing season has been declared active. The GFS
and NAM suggest ridging in place aloft over the plains
tonight...leading to NW lee side flow and subsidence across
Indiana. This will result in a strong high pressure system
building across the region. Forecast soundings and time height
show a dry column...thus mostly clear skies with light to calm
wind overnight will make for ideal radiational cooling conditions.
With dew points in the lower 20s expected...temps below 32 appear
pretty reasonable.

Otherwise...the NAM and GFS suggest a slow progression of the
upper ridge to west of Indiana through Saturday night. Mainly
Indiana remains within the lee-side NW flow through
Saturday...with the ridge axis arriving Saturday night. Forecast
soundings respond with a very dry column through Saturday night.
Thicknesses show a slow increase through Saturday
also...indicating a slow moderation of the air mass and slightly
warmer air arriving by Saturday as the surface flow becomes a bit
more easterly as opposed to the Northerly flow expected tonight
and Friday. Thus will trend toward partly cloudy days and mostly
clear nights...trending lows at or below the forecast builder
blends and sticking close to the blends on highs.


.LONG TERM /Sunday through Wednesday Night/...

Issued at 341 AM EDT Thu Apr 19 2018

Confidence remains high early in the extended period as blended
initialization continues to trend toward dry conditions from
Sunday into Monday. The ridge of high pressure will be disrupted
by a low pressure system to the south though on Monday. Latest
model runs show the Euro coming into line with the more
southeasterly route of the GFS. However, models are still not in
great agreement completely in regard to tracking and timing of
this system, so will continue with low to moderate confidence
during this time frame of the forecast. Nonetheless, a few rain
showers could skim the southern counties (mainly SE) from Monday
into Tuesday.

Further out, a closed upper low will track across the Upper
Midwest and start impacting central Indiana late Tuesday. Rain
chances will be best with this system through Wednesday.
Meanwhile, temperatures through the period will be either at or
slightly below normal at times.


.AVIATION /Discussion for the 19/06Z TAFs/...
Issued at 1145 PM EDT Wed Apr 18 2018

MVFR will be the predominant condition during the overnight into
Thursday morning, with a period of IFR around daybreak.

A few rain and/or snow showers cannot be ruled out with the upper
low but should be light and chances are low enough at the sites to
exclude an explicit mention for the most part. Visibilities will
be unrestricted throughout, outside of any potential showers.

Winds will be a significant impact during this period with gusts
in excess of 25KT possible especially early in the period. Gust
speeds will drop off gradually overnight into Thursday, although
winds will remain gusty much of the period. Winds will generally
be northwesterly, becoming more northerly later in the period.


Freeze Warning from midnight tonight to 9 AM EDT Friday for



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