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Area forecast discussion 
National Weather Service Indianapolis in
419 PM EDT Friday Mar 27 2015

Area forecast discussion
National Weather Service Indianapolis in
419 PM EDT Friday Mar 27 2015

the aviation section has been updated below.


issued at 255 PM EDT Friday Mar 27 2015

A strong high amplitude upper trough over the eastern U.S. Will
produce near record low temperatures tonight and unseasonably cold
temperatures through Saturday night. Temperatures will begin a slow
moderation early next week as the upper trough moves on to the east
and a more zonal upper flow sets up.

A frontal system will bring chances of light rain Sunday afternoon
and night. Another cold front will produce a chance of thunderstorms
late Wednesday and Thursday of next week. An approaching warm front
will produce a slight chance of showers by day 7.


Near term /tonight and Saturday/...
issued at 255 PM EDT Friday Mar 27 2015

Arctic high pressure from the upper Midwest to the Central Plains
will build towards Indiana by Saturday. Satellite currently shows
lots of clouds and a few flurries across our region. But with
sunset clouds should diminish quickly this evening. Model soundings
indicate little in the way of clouds after 03z tonight. Will slow
down clearing a little some areas this evening...but by late tonight
all areas should be clear. Light winds...clearing skies and very
cold air aloft will allow temperatures to drop to near record values
in the middle to upper teens. Went close to a MOS blend on
temperatures most areas.

Saturday will be mostly sunny as high pressure builds into our
area. Model soundings indicate a very dry airmass. Given the late
March sunshine will lean towards the warmer mav temperatures on
Saturday with highs from the middle 30s over northeast sections to
the lower 40s in our southwest.


Short term /Saturday night through Monday/...
issued at 255 PM EDT Friday Mar 27 2015

High pressure will begin to move off to the east Saturday
night...and some warm advection will occur late Saturday night.
Still a MOS blend in the lower 20s still look reasonable as there
will be good radiational cooling Saturday night.

On Sunday we can expect increasing clouds with a chance of rain
Sunday afternoon as a cold front moves into our region. Models are a
little more progressive as they end any chances of rain by late
Sunday night. Models then move a weak high pressure area into the
Ohio Valley by Monday. Will mention a chance of rain Sunday
afternoon and evening. Some models hint at patchy fog late Sunday

Highs will be in the middle 40s to middle 50s Sunday with lows in the 30s
Sunday night. Monday will see highs in the 50s...except near 60
across our southwest.


Long term /Monday night through Friday/...
issued at 245 PM EDT Friday Mar 27 2015

The extended timeframe begins with the forecast area under the
influence of surface high pressure...northwest flow aloft...and an
area of low pressure approaching the Great Lakes from the upper
Midwest. As the low pressure passes to the north...winds strengthen
to out of the southwest then west during the day allowing for a
return to the 60s for most of the area. Better moisture and lift
remains further north closer to the low. Thus...removed pop Monday
night and Tuesday.

Here is where the models differ drastically. 00z Euro digs the upper
trough into the Middle-Atlantic States...dropping the associated
frontal boundary south into the southeastern states. 12z GFS however
spreads the upper wave across the northeast states...allowing a
stationary boundary to be draped east to west just north of the
forecast area Tuesday night and Wednesday...before retreating north
as a warm front Wednesday afternoon and evening. Stuck close to the
regional initialization during this period of uncertainty...which
includes increased pop Wednesday and Wednesday night owing to warm air advection
showers and an approaching cold frontal boundary boundary. The 00z
Euro is approximately 6 hours quicker with this feature and impacts.
With some instability available...currently expect thunder as this
frontal boundary pushes across the area. For Friday...00z Euro
brings a strong storm system into the Great Lakes/Ohio River valley
region. Not too keen on this occurring and the 12z GFS
differs...filtering high pressure in behind the aforementioned cold
front. Decided to drop probability of precipitation from chance into the slight chance
category since confidence in Euro solution not high.

High temperatures in the middle 50s to middle 60s characterize the
extended timeframe.


Aviation /discussion for the 272100z kind taf update/...
issued at 419 PM EDT Friday Mar 27 2015

Scattered light snow showers in progress in the vicinity of
kind...but appears any impact on ceiling or visibility will be brief
or negligible. These showers should end with sunset.

No significant changes made to the forecast at this time. Previous
discussion follows.

Borderline MVFR/VFR conditions still holding on across most of the
terminals early this afternoon. Decided to keep all sites VFR as we
have seen some upward movement in the ceiling thus far and will
continue to see some gradual improvement into the middle-afternoon
hours. Winds have not been consistently gusting yet so decided to
back off on the gusts for 2 to 3 hours...staying with sustained
northerly winds from 10 to 13 knots until around 18/1900z. Then the
gusts will be reinstated. not be surprised to see a few
snow flurries cross the taf sites. These are almost impossible to
time for arrival and departure and from what we have seen here at
ind...the impacts should be minimal with most visibilities remaining
at or above 6 sm. Laf would possibly be the only exception to that
as visibilities have recently dropped as low as 2sm...but continue
to bounce between 2 and 6 sm. Confidence not high that the low
visibilities will continue. not plan on including in laf taf.

Expect skies to clear this evening and remain clear through Saturday
as high pressure filters in from the northwest. Strong northerly
winds will begin to subside overnight...leading to 5 to 10 knot
winds for Saturday.


Ind watches/warnings/advisories...


near term...jh
short term...jh
long term....mrd

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