Scientific Forecaster Discussion
fxus63 kind 190445
Area forecast discussion
National Weather Service Indianapolis in
1145 PM EST Mon Nov 18 2019
the aviation section has been updated below.
issued at 342 PM EST Mon Nov 18 2019
Tomorrow, there is a chance of showers in the early morning that will
linger into the afternoon hours. Early on, mixed precipitation
is possible in our northern most counties. Tuesday night and Wednesday
will bring dry and seasonal temperatures. Our next chance of
precipitation enters our region on Thursday, along with a brief warm
up to above normal temperatures.
Near term /overnight/...
Issued at 937 PM EST Mon Nov 18 2019
Surface analysis late this evening shows a ridge of high pressure
in place over Indiana with a larger surface trough in place across
Iowa and Missouri. Goes16 shows abundant cloud cover upstream of
Indiana...ahead of the approaching upper trough. This should keep
skies cloudy overnight as well as limit cooling. Time heights and
forecast soundings keep saturation present within the lower
levels. Thus have trended sky grids toward cloudy overnight and
trended lows at or above nbm temps due to a lack of radiational cooling.
Short term /Tuesday night through Thursday/...
Issued at 339 PM EST Mon Nov 18 2019
The primary focus for the period will be Wednesday night into
Thursday as a fairly strong low pressure system brings widespread
rain to central Indiana. Dry weather is expected from Tuesday night
through early Wednesday night as high pressure builds behind the low
pressure system that is expected to move through tomorrow. High
pressure will exit Wednesday night ahead of the strong low pressure
system and associated surface front. This system will bring
widespread rain to the area Wednesday night into Thursday.
Confidence in rain is high for Thursday with good model agreement on
timing of the system. Confidence in the axis of higher
precipitation is lower with the subtle differences in location of
best forcing, so kept the quantitative precipitation forecast fairly broad-brushed at a quarter to
third of an inch.
High temperatures are expected to reach into the low 50s on
Wednesday followed by upper 50s to low 60s on Thursday. Lows will
fall into the low 30s Tuesday night and the upper 30s to low 40s on
Long term /Thursday night through Monday/...
Issued at 246 PM EST Mon Nov 18 2019
The long term begins with a cold front moving east through the
forecast area and an upper trough approaching from the west. This
will keep chances for rain in the forecast through early Thursday
night and small chances in the southern and eastern counties into
Friday morning. Cold advection will get going Thursday night and
Friday should see highs back in the 40s for the weekend. There is
variety in the ensembles regarding another surface wave moving
northeast out of the Gulf Coast/plains, with some runs keeping
this feature well to the south and keeping central Indiana dry,
while others bring it to near the Ohio River and bring additional
chances for rain or snow to the area Friday night through Saturday
night. Confidence in pops for that period is therefor low. However
there is good agreement on ridging building in for Sunday through
Monday, so better confidence in dry weather on these days.
Aviation /discussion for the 190600z taf/...
Issued at 1145 PM EST Mon Nov 18 2019
MVFR conditions are are expected to improve to VFR briefly overnight
before returning to MVFR and IFR on Tuesday.
A weak surface ridge over Indiana will exit early overnight
allowing some some higher clouds over western Indiana to arrive
Another round of showers and MVFR to IFR conditions are expected
on Tuesday as the models indicate another short wave with the
broad upper trough aloft passing across Indiana during the late
morning and early afternoon. Time heights and forecast soundings
reveal saturated lower levels at that time with decent lift
present. Thus will expect precip along with MVFR ceilings. As the best
forcing departs...trapped strato-cu appears to linger within the
forecast column...indicating MVFR to IFR ceilings.