Scientific Forecaster Discussion
fxus63 kind 191032
Area forecast discussion
National Weather Service Indianapolis in
632 am EDT Thu Oct 19 2017
the aviation section has been updated below.
issued at 340 am EDT Thu Oct 19 2017
Dry weather with low to mid 70s for highs will be the rule through
Saturday under high pressure. Late Saturday night chances for
showers will move in from the west as an upper trough approaches.
A weak cold frontal passage Sunday will bring rain, and then a
stronger cold frontal passage will bring colder temperatures to
the area from Tuesday Onward. The more active pattern that starts
late Saturday night will keep rain chances in the forecast for at
least parts of central Indiana through Wednesday.
Near term /today/...
Issued at 340 am EDT Thu Oct 19 2017
High pressure over the eastern half of the U.S. Will keep dry
weather and clear skies over central Indiana. High temperatures
will climb another couple of degrees from yesterday under full
sunshine and a slowly moderating airmass. Excellent model
agreement yields a high confidence forecast.
Short term /tonight through Saturday night/...
Issued at 340 am EDT Thu Oct 19 2017
High confidence in dry weather through Saturday for central Indiana
with a strong upper ridge moving across the central and eastern
U.S. Highs will be in the middle 70s, with lows in the upper 40s
to lower 50s tonight and the low to mid 50s Friday night.
The pattern begins to change Saturday night as the upper ridge
moves off to the east and an upper trough approaches from the
west. This will bring chances for rain into the western counties
by late Saturday night. Given the small model qpf amounts and
disagreement on whether or not the forcing and moisture will
arrive prior to 12z Sunday though, relatively low confidence on
those precip chances. While there is some indication of a little
elevated instability, it isn't much, and with the low confidence
of precip prior to 12z anyway will leave out any thunder mention.
Long term /Sunday through Thursday/...
Issued at 327 am EDT Thu Oct 19 2017
Big changes coming to the region early to mid-week.
Models are in good agreement in sharp, high amplitude mid/upper
level trough entering the center of the Continental U.S. Saturday night into
Sunday morning. Mid/upper level low is expected to develop over
the Southern Plains/lower MS valley region creating a split flow
over the Ohio Valley. This feature is expected to continue
eastward through the southern states as its kicker in the form of
a another high amplitude trough moves into the upper Great Lakes
southward into the mid MS valley on Monday. By Tuesday evening
a mid/upper level low will develop over the Illinois/in/OH region.
Large band of light/moderate rain will be moving into the region
by Sunday afternoon ahead of the first strong cold front, as a
surface low develops in association with the lower MS valley
trough, around southeast MO/southern Illinois. Moderate low level flow
of up to 40 kts will run northeast ahead of the front enhancing
moisture/warm advection into the area. Thus, expect that
strong/severe weather be possible south of Indiana, but will
increase the impact of moderate/locally heavy rain across parts
of central in into Sunday night.
Second strong cold frontal boundary is expected as it drops
southeast Monday night and as a strong mid/upper level jet stream
drops southward over the northern High Plains then eastward over
the Tennessee Valley, bringing with it the coolest air of the
season. Cloudy, rainy weather will continue to be the main
impacts along with occasional gusty winds with the frontal passage
Monday going into Tuesday.
The temperatures will be mild to start the week on Sunday with
highs in the low-mid 70s and lows in the mid 50s Monday morning,
then dropping into the mid 50s for highs Wednesday with lows in
the low 40s throughout the region Wednesday morning, and upper
30s/lower 40s Thursday morning.
Aviation /discussion for 191200z taf issuance/...
Issued at 627 am EDT Thu Oct 19 2017
VFR through the period. Only a few cirrus today and tonight with
winds out of 180-210 around 5 to 10 kts today and less than 5 kts
overnight. Some guidance showing some potential for fog Friday
morning near the end of taf period, but very low confidence so
will leave out for now.