Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Indianapolis in
315 PM EST Monday Nov 24 2014
the aviation section has been updated below.
issued at 340 am EST Monday Nov 24 2014
Colder air will return to central Indiana later today behind the
low pressure system and cold front currently impacting the area.
As a result...rain will transition to snow late this
afternoon/evening...but accumulations will be minimal. After a
chilly but dry day tomorrow...another system will bring light rain
and snow on Wednesday. Further out...Thanksgiving day into the
weekend will be cold but dry...and precipitation will return again
Near term /rest of today and tonight/...
Issued at 1016 am EST Monday Nov 24 2014
For the update...removed thunder chances with the cold front
through the area and all thunder off to the east. Decreased probability of precipitation
this afternoon across the north but added some low probability of precipitation to the
south based on recent runs of the hrrr and rap and weak wave
approaching from the southwest. Also transitioned to rain snow mix a little
faster in the northwest based on current observation of snow in
Illinois...but still think the majority of that will head off to
the northeast and miss the forecast area. Still not expecting much
if any accumulation. Bumped high end of wind gusts up to 50 miles per hour in
the npw. Temperatures will fall for the remainder of the day.
Previous discussion follows...
The main focus of the near term period will be the strong
southwest winds...as well as precipitation chances and types.
An area of low pressure is currently positioned over lower
Michigan with a warm front stretching across Ohio...and a trailing
cold front tracking across Illinois. Current radar mosaic shows
scattered showers with a few isolated thunderstorms over much of
Illinois and the southern half of central Indiana. Forcing from
the cold front will justify likely probability of precipitation through late morning.
However...best forcing will become confined to the northern
counties this afternoon as upper trough moves through the area. As
a result...will only carry mention of precipitation over the northern
half of central Indiana into tonight...and will go with a dry
forecast across the southern half. Rain will transition to snow
late this afternoon/evening...but accumulations will be minimal
since most moisture will be out of the area.
Temperatures will start out in the 50s this morning...but quickly fall
into the middle 30s through the course of the day as colder air
enters the area. Tonight...overnight lows will fall into the upper
20s...stuck close to guidance.
A Wind Advisory remains in effect for all of central Indiana today
as pressure gradient tightens. Sustained speeds out of the
southwest are expected to be between 20 to 25 miles per hour with gusts up to
45 miles per hour at times.
Short term /Tuesday through Wednesday night/...
Issued at 340 am EST Monday Nov 24 2014
Dry and cooler weather will prevail on Tuesday. However...the
pattern will become more active again by Wednesday as an upper
trough tracks across the lower Midwest. Precipitation should be in the
form of rain across the southern half of central Indiana on
Wednesday with a rain/snow mix over the northern half. As temperatures
fall on Wednesday night though...precipitation will transition to snow.
Models have this disturbance moving through quickly though...so
snow accumulations should be relatively low...less than an inch.
High temperatures through the short term period will be in the 30s with
lows in the 20s. The mav continues to look a tad too warm...so
stuck closer to a model blend.
Long term /Thursday night through Monday/...
Issued at 232 PM EST Monday Nov 24 2014
Zonal flow will commence through the first half of the
weekend...keeping conditions mainly dry. The next system is due to
impact the region Saturday night into Sunday night with chances for
rain...and even a rain/snow mix possible over the northern counties
Sunday night. Precipitation accumulations still look very light at this
time so left probability of precipitation at slight to low end chances. Superblend guidance
initialized well. Only need to make a few minor tweaks.
Aviation /discussion for 242100z taf update/...
Issued at 315 PM EST Monday Nov 24 2014
MVFR ceilings will prevail through the entire period. Indicated
either a prevailing -shsn or a tempo group until evening to
account for the scattered light snow showers which are developing
over central Indiana. Per recent observation not expecting any reductions
in visibility...however it/S possible a few stronger shsn may
briefly drop conditions to MVFR at a few of the sites.
Gusty winds will continue until late tonight. Strong west to
southwest winds up to 25 knots and gusts 30 to 40 knots will
continue through this afternoon. Winds will decrease some this
evening as the pressure gradient relaxes a little...then become 10
knots or less by early Tuesday morning.
Wind Advisory until 7 PM EST this evening for inz021-028>030-
Wind Advisory until 10 PM EST this evening for inz031-038-
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