Scientific Forecaster Discussion
fxus63 kind 220406
Area forecast discussion
National Weather Service Indianapolis in
1105 PM EST Thu Nov 21 2019
the aviation section has been updated below.
issued at 328 PM EST Thu Nov 21 2019
Any lingering showers tonight and tomorrow morning will become
mainly confined to the southern portions of central Indiana as a
cold front sinks farther south into the area. After a brief break
in systems on Friday due to high pressure, the next system is
then progged to move through the Tennessee Valley from Thursday
night through Saturday, spreading precipitation northward across
central Indiana. After that, dry conditions will prevail Saturday
night through Monday before the next system moves in just before
Near term /tonight/...
Issued at 328 PM EST Thu Nov 21 2019
Current synoptic setup shows low pressure centered over the Great
Lakes region with its associated warm frontal boundary stretching
into the Ohio Valley, quickly followed by the cold front. Current
radar mosaic is rather quiet, but will carry pops into the night
to account for trailing upper low. The highest chances, however,
will be confined to the southernmost counties where forcing will
be best near the cold front. Meanwhile, west winds will gradually
weaken through the evening hours as the low level jet shifts
farther east, and then they will shift to the northwest after
midnight. Sustained speeds will range between 10 to 15 mph with
gusts up to 25 mph. Overnight lows will dip closer to normal in
the wake of the aforementioned cold front with readings in the low
to upper 30s.
Short term /tomorrow through Monday/...
Issued at 328 PM EST Thu Nov 21 2019
Low rain chances will persist into Friday morning across the
southernmost counties. But, even those should subside by mid-
morning, making the entire forecast area dry through the afternoon
as brief ridging strengthens over the region.
The dry weather will be short lived though as the next system
moves into the Tennessee Valley on Friday night and Saturday
morning. So, pops will start overspreading the forecast area again
from the southwest by Sat 00z. Still not convinced on the freezing
rain potential, will continue to go rain (south), snow/rain
(central), and snow (north) for Friday night and Saturday morning.
Any snow accumulations though will be minimal. As temperatures
increase into the 40s on Saturday, precipitation will
predominantly become rain before snow mixes in again Saturday
Further out, weak ridging will bring dry conditions for Sunday and
Monday. Meanwhile, temperatures through the period will be below
normal with highs in the 40s and lows generally in the 20s and
Long term /Monday night through Thursday/...
Issued at 227 PM EST Thu Nov 21 2019
Mainly dry weather bookends this period with a strong chance for
rain mid week.
The European model (ecmwf) suggests quick flow in place aloft on Monday and night
through Tuesday with little in the way of forcing dynamics aloft.
Meanwhile at the surface southerly surface flow remains in place
ahead of an approaching trough over the plains.
On Tuesday night through Wednesday a strong upper trough and
associated surface flow are expected to arrive and push across
central Indiana. Plenty of moisture remains available.
Temperatures looks to remain warm enough for the bulk of
precipitation to remain as rain...however as cold air arrives in
the wake of the cold front on Wednesday with wrap-around type
precipitation. Thus will trend toward higher pops on Tuesday
through Wednesday night.
Strong ridging looks to build across the area for
Thanksgiving...which should give US a return to dry and pleasant
weather with seasonal temps.
Aviation /discussion for the 220600z taf issuance/...
issued at 1105 PM EST Thu Nov 21 2019
Good confidence in MVFR and worse conditions per the GFS lamp
through 14z-16z. A few light showers are also possible mainly at
khuf and kbmg through 08z or so.
Winds will northwest and north less than 10 knots.