Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 261834
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
234 PM EDT Thu Apr 26 2018

.UPDATE...
The LONG TERM section has been updated below.

&&

.SYNOPSIS...
Issued at 332 AM EDT Thu Apr 26 2018

High pressure will keep it dry through Friday. Then, an upper wave
will bring a few showers to mainly northern sections Friday night.
After that, high pressure will again lead to dry weather until the
middle of next week, when a frontal system will bring a threat for
showers to the area.

Temperatures will be near normal until Saturday, when cooler
temperatures will filter in in the wake of a cold front. Then, look
for a big shift with above normal temperatures next week.

&&

.NEAR TERM.../Rest of Today/
Issued at 950 AM EDT Thu Apr 26 2018

Forecast is on track. Some lower clouds were trying to sneak into
northeast sections of the forecast area, but they are dissipating as
mixing begins. High clouds will continue at times across mainly the
south. Temperatures look good.

Previous discussion follows...

Temperatures and cloud cover will be the main focus today.

Goes 16 water vapor imagery was showing an upper low spinning over
Arkansas. Infrared imagery was showing mid and high clouds from just
north of the I-70 corridor and south. Meanwhile, areas further north
had clear skies light northerly winds and temperatures only in the
middle and upper 30s at 3 am. So, expect patchy frost over the
northern counties through around 9 am. Reissued a Special Weather
Statement to cover that. Otherwise, models in good agreement that
the Arkansas low will move across the Tennessee Valley today and the
showers should stay north of our forecast area. That said, will keep
some clouds in our southern two tiers with little cloud cover over
the rest of central Indiana.

Low level thermals and expected cloud cover support the near normal
blend highs in the middle 60s today.

&&

.SHORT TERM.../Tonight through Saturday night/
Issued at 332 AM EDT Thu Apr 26 2018

Shower timing and coverage along with temperatures will be the main
focus for the short term.

Models in good agreement that surface high pressure and limited
moisture will result in dry weather through Friday. However, models
also agree that a wave will rotate around a Great Lakes upper low
and over northern sections of central Indiana Friday night. Models
all have QPF over our northern counties as well. So, confidence is
moderate or better that at least areas north of Indianapolis will
see some showers Friday night. Blend 40 percent PoPs over our north
looks ok with lesser chances over the metro area. In addition, a
cold front will move through Friday night and bring cooler air in
for Saturday.

Blend temperatures look ok with near normal highs in the 60s on
Friday but well below normal temperatures on Saturday in the wake of
the cold front. Could even see a freeze Saturday night, especially
over our northern counties, as the surface high settles over the
area allowing for great radiational cooling potential. Headlines may
be needed if confidence remains high as Saturday night gets closer.

Models are close enough that the model blend initialization was
accepted for most items.

The upper low moving across the southern states will keep some
clouds across the area Thursday, mainly south.

A cold front will move through on Friday, but moisture will be quite
limited as the system to the south will have taken most of the
moisture with it. Will continue with a dry forecast during the day.

Friday night, an upper level system will move into the Great Lakes
region. The GFS is stronger than the rest of the models and spreads
rain well into central Indiana. Most other models are farther north
and weaker. However, the SREF does bring some rain chances into
northern areas. Thus, confidence is low in PoPs Friday night, and
will make no changes to the intialization`s low PoPs north then.

Colder air moves back in behind the system Saturday. Went a little
cooler than the initialization northeast given latest trends in the
models.

&&


.LONG TERM /Sunday Night Through Thursday/...
Issued at 234 PM EDT Thu Apr 26 2018

Models are close enough that the model blend initialization
was accepted for most items.

Warm weather will be the rule next week as an upper ridge builds
over the area early in the period then slides to the east.

As the ridge moves to the east, the area will be put in southwest
flow aloft as an upper low digs across the southwestern USA, and
northern stream systems remain to the northwest of the area.

Pieces of energy will eject from the upper low, and some influence
from the northern stream systems will be felt by mid-week next week.
This will be enough to bring the threat of rain Tuesday night on.

Of course that far out timing and strength of forcing is quite
uncertain, so uncertainty is high for the timing of the highest PoPs.

&&

.AVIATION (Discussion for the 261800Z TAF Issuance)...
Issued at 1254 PM EDT Thu Apr 26 2018

VFR conditions expected through the period.

Mainly high clouds are expected through most of the period, with an
increase in mid cloud late in the period.

A surface front will move through late tonight into early Friday,
which will cause the winds to vary from west to northwest.

&&

.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SYNOPSIS...MK
NEAR TERM...MK/50
SHORT TERM...MK
LONG TERM....50
AVIATION...50



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