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Area forecast discussion 
National Weather Service Indianapolis in
945 PM EDT Wednesday Oct 1 2014

Update...
near term for the rest of tonight has been updated below.

&&

Synopsis...
issued at 342 PM EDT Wednesday Oct 1 2014

A potent upper trough and strengthening frontal system will begin
to push toward the area late tonight into Thursday...with a strong
cold front blasting through the area tomorrow night into early
Friday. Ahead of the front...showers and thunderstorms are
expected...especially tomorrow night. Behind the front...much
colder air will spill into the region...with temperatures falling
well below seasonal normals over the weekend.

&&

Near term /rest of tonight/...
issued at 945 PM EDT Wednesday Oct 1 2014

Current forecast is on track and only minor tweaks made to grids.
The remains of a thunderstorm complex has pushed into west central
Illinois and will reach our northwest sections late tonight as it
continues to weaken. Will continue chance probability of precipitation along and west of a
Kokomo to Vincennes line late tonight and raise probability of precipitation a little west
of Lafayette based on radar trends.

Tweaked temperatures up slightly across the west half. But overall
no significant changes made. Lows tonight will range from the middle
50s Randolph County to the lower 60s west and southwest.

&&

Short term /Thursday through Saturday/...
issued at 342 PM EDT Wednesday Oct 1 2014

Weak isentropic lift will continue to overspread the area on
Thursday...but any showers/isolated storms likely to be no more
than widely scattered in nature...with the widespread
precipitation nearer the front. Isentropic lift will increase
rapidly tomorrow evening as the front approaches...accompanied by
a 40 to 50 knots low level jet. Thus expect greater coverage of
thunderstorms tomorrow night despite limited convective
instability. Far western portion of the area is in a slight risk
for day 2...and this is reasonable. Any severe threat appears
likely to be marginal at best at this point with adequate shear
but weak instability. Will have to carry a thunder mention into
early Friday before dropping it altogether per sref Post processed
thunder probabilities. Showers may linger across portions of the
area through the remainder of the short term as the potent upper
low passes through the region.

Temperatures will become the main story after the frontal
passage...with guidance suggesting rapidly falling temperatures
after reaching maxes sometime Friday morning. Lows across much of
the area as early as Friday night appear likely to drop into the
upper 30s...with highs Saturday struggling only into the low to
middle 50s...with some upper 40s across northern portions of the
forecast area not entirely out of the question. Certainly a rude
awakening to the changing of the seasons...especially for those
who have enjoyed the recent mild and dry weather.

&&

Long term /Saturday night through Wednesday/...
issued at 342 PM EDT Wednesday Oct 1 2014

Ensembles suggest another upper disturbance will drop into the area
around early next week. Will go with and/or continue chance to
slight chance probability of precipitation at times. Long range operational models suggest
some convective potential with this system however for now left out
mention of thunder based on very weak instability and forcing
mechanisms. Allblend initialization seemed reasonable and only
needed to make minor modifications.

&&

Aviation /discussion for 020000z taf issuance/...

Issued at 701 PM EDT Wednesday Oct 1 2014

The main focus for this set of tafs will be an issues associated
with rain and potential for convection. Radar mosaic shows showers
and thunderstorms out across eastern Missouri and western Illinois
and rapid update models show this area moving into the western sites
around 9z. Not sure if there will be much lightning with it by that
point or how much rain will be left so at this point included a vcsh
and a broken VFR deck to indicate the potential but also keep in
mind the uncertainty. Kbmg and kind look like they will be east
enough to stay dry. Models are indicating some potential for a break
in the west from middle morning through middle afternoon or so and dropped
the vcsh during this time. Brought it back in after 20z at the
western sites and after 0z at kind. More thunderstorms are possible
with this second round but timing/placement still uncertain enough
to leave out and try to pin down better with later issuances.

&&

Ind watches/warnings/advisories...
none.
&&

$$

Synopsis...nield
near term...jh
short term...nield
long term...smf
aviation...cp

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