Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Indianapolis in
1009 am EDT Wednesday Jul 23 2014
the aviation section has been updated below.
issued at 152 am EDT Wednesday Jul 23 2014
A quick moving cold front will sweep across central Indiana early
this morning...reaching the Ohio River by this afternoon. This
will result in isolated shower or thunderstorm chances this morning
across central Indiana...followed by a dry and cooler and afternoon.
High pressure from Canada will then build across the Hoosier state
tonight through Friday...providing dry weather with below normal
A series of upper level weather disturbances are expected to
pass through Indiana and the Ohio Valley this weekend...bringing
chances for showers and storms.
Near term /today/...
Issued at 930 am EDT Wednesday Jul 23 2014
Quite a bit of convection has redeveloped behind the stuff that
crossed the County Warning Area this morning. Therefore the update
will have considerably higher probability of precipitation than the earlier forecast into
the afternoon. As a cold front now entering the northwest part of
our area continues south...drier air should kill off the
precipitation during the afternoon.
Short term /tonight through Friday night/...
Issued at 152 am EDT Wednesday Jul 23 2014
Models are in pretty good agreement during this period and will
use a blend overall. A quiet end to the work week looks in store
as tonight through Friday will be dominated by high pressure
setting across the region from central Canada. This cool and dry
Continental air mass will provide cooler than normal and dry
weather conditions through Friday. Forecast soundings through the
period show a dry column along with unreachable convective
temperatures. Middle levels through the period remain dry with
subsidence. The flow aloft through the period remains quick and
front the northwest...thus a few passing cirrus will be possible from
time to time. Forecast soundings confirm that with occasional
saturation appearing aloft. Thus will trend toward partly cloudy
skies during this period along at or below mavmos.
By Friday night flow aloft remains progressive and from the
northwest. GFS hints at a short wave arriving in the area during
the evening hours...while the NAM is a bit quicker. Forecast
soundings beginning to hint at a top down saturation...and
southerly and more humid flow will have arrived. Will include some
chance probability of precipitation for now at this time on Friday night...however timing and
progression will remain highly changeable at a period this far way
in the wake of departing high. Will trend temperatures a bit warmer than
mavmos on Friday night given expected clouds and possible rain.
Long term /Saturday through Tuesday/...
issued at 220 am EDT Wednesday Jul 23 2014
Models are similar with the overall pattern in the long term so used
a blend. Allblend initialization had some problems so deviated from
it when necessary.
Through the long term another upper trough will deepen across the
eastern USA. This will result in a cooling trend and frequent
chances for rain.
During the weekend a couple of areas of low pressure will move
through the region bringing cold fronts with them. Uncertainties in
timing that far out preclude going any higher than chance category
probability of precipitation for any one period.
On Monday as the upper trough digs another surface trough will bring
low chances for rain. After that there appears to be a brief break
in rain chances as high pressure sneaks in from the west.
Aviation /updated discussion for the 231200 taf issuance/
.Issued at 1009 am EDT Wednesday Jul 23 2014
Thunderstorms continue to move south and southeast across central
Indiana at this time resulting in occassional LIFR conditions. This
activity should be through kind within the next 30 minutes or so
then MVFR for the most part through the next udate at 1800z. IFR
conditions observed over Northwest Indiana at this time should make
its way into the area towards mid-afternoon.
.Previous discussion below..
Scattered convection through the morning hours with a period of MVFR
ceilings outside of convection...then VFR this afternoon on.
Radar shows scattered convection developing behind an outlfow
boundary moving across the area. Feel that convection should begin
to wane as is typical for near sunrise so for now will just have
thunderstorms in the vicinity.
Cold front will move through this morning shifting winds to the
northwest. Models showing some additional convection this morning
with the front...but most of it should be south of the sites. Will
use vcsh. Numerous MVFR ceilings associated with the front...so will
include a period of MVFR this morning.
Drier air works in this afternoon and returns conditions to VFR.
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