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Area forecast discussion 
National Weather Service Indianapolis in
638 am EST sun Nov 29 2015

the aviation section has been updated below


issued at 315 am EST sun Nov 29 2015

A frontal boundary will remain over the Tennessee Valley through
tonight as an upper ridge settles over the area. This will result in
dry conditions across most of central Indiana through tonight.
However...would not rule out a light rain shower or two across south
central parts of the area early this morning and again tonight.
Then...low pressure will develop along the front as it lifts
northeast allowing the rain to spread northeast across the rest of
central Indiana Monday and Monday night. As the frontal system moves
east of the area on Tuesday...the rain will be ending. After
that...high pressure will provide dry weather through next weekend.

Temperatures will be slightly above normal most periods through next


Near term /today/...
issued at 315 am EST sun Nov 29 2015

Main focus for today will be cloud cover and also shower chances far

Models in good agreement that a frontal boundary will remain stalled
across the Tennessee Valley today as an upper ridge moves over the
area and surface high pressure moves east across Ontario and Quebec.
Northeast low level winds around the high will bring drier air in as
seen clearly in the model relative humidity time sections. This should bring a few
breaks in the low clouds to areas north of Noblesville by late
morning and possibly as far south as Interstate 70 late in the

Radar was still showing some showers around...mainly south
central...but with drier air moving in along with isentropic
downglide and 00z models showing none quantitative precipitation forecast...will pull the probability of precipitation south
at least after 12z this morning. Will just go with a small chance of
pre-first period probability of precipitation before that and update if the showers are
still around nearing 12z.

With 850 millibar temperatures from 6 degrees celsius north to 8
degrees celsius south...look for the slightly above normal
temperatures to continue today...even across the south where the
thick clouds should remain. 00z MOS highs in the middle and upper 40s
look reasonable.


Short term /tonight through Tuesday night/...
issued at 315 am EST sun Nov 29 2015

Forecast focus will be on timing of the rain back into the area as
Great Basin upper low finally ejects northeast and spins up a
surface low over the Missouri Valley on Monday. This low will then
lift north and take the tenneesee valley front northeast with it as
a warm front. The warm front should lift northeast over central
Indiana late Monday and Monday evening. Meanwhile...the system will
become occluding with a triple front near Southern Lake Michigan
Tuesday morning and a trailing cold front across east central

The European model (ecmwf)...NAM and Gem continue to be quicker and deeper with the
upper low through Monday evening compared to the GFS. The 00z Sunday
run is no exception. Thus...will continue to favor a non-GFS blend.

Based on 300k isentropic analysis...isentropic lift will pick up
tonight. However...with dry northeast will take awhile for
atmosphere to saturate down. 00z European model (ecmwf) condensation pressure
deficits lower to around 30 millibars from just north of Vincennes
around 06z Monday and to just north of a Terre Haute to North Vernon
line by 12z Monday. The 30 millibar condensation pressure deficit
line is often near where the atmosphere is able to saturate enough
for overrunning precipitation to reach the ground in the presence of
isentropic lift. So...will start with small late evening probability of precipitation far
southwest and gradually introduce probability of precipitation further northeast overnight.

The rain should increase and spread northeast across the rest of the
forecast area Monday. Monday night looks like it will see the
greatest coverage as 40 a knot low level jet moves into northern
Kentucky and far southern Indiana. However...with the cold front
moving east of the area on Tuesday...things should wind down. As
such...continued with increasing probability of precipitation Monday and highest probability of precipitation Monday
night with likely category in order. Will have to continue to keep
an eye on elevated instability Monday night. However...latest
instability forecasts do not support thunder mention at this time.

With drier air moving in behind the cold front...should see some
clearing on Tuesday afternoon. However...the clouds should return
Tuesday night with the upper low moving across Lake Michigan. Relative humidity
forecasts also suggest there will be enough moisture around to squeeze
out a few light rain or snow showers across the northern forecast
area. and preciptation considerations suggest similar
slightly above normal 00z MOS temperatures look good through the


Long term /Wednesday through Saturday night/...

Issued at 342 am EST sun Nov 29 2015

Residual rain/snow showers will linger over the north/northeast
portions of central Indiana on Wednesday on the back side of an
upper low. No accumulations are expected. After that...high
pressure will dominate the remainder of the extended
period...resulting in dry conditions from Wednesday night through
Saturday night. A weak warming trend will occur through the period
with slightly below highs on Wednesday in the low to middle
above normal highs on Saturday in the upper 40s/low 50s. Overnight
lows will range from the upper 20s to middle 30s.


Aviation /discussion for the 29/12z taf issuance/...

Issued at 632 am EST sun Nov 29 2015

Clouds have been slower to clear out than originally
expected with sites still reporting MVFR/IFR levels. Frontal
boundary remains draped across Tennessee and southern
Kentucky...and drier air will continue to filter into the region
as high pressure strengthens to the west. VFR conditions should
start prevailing around middle to late morning...then continuing
through end of taf period. Winds will be northeasterly at 8 to 11


Ind watches/warnings/advisories...none.


long term....tdud

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