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Area forecast discussion 
National Weather Service northern Indiana
752 PM EDT Tuesday Oct 13 2015

issued at 752 PM EDT Tuesday Oct 13 2015

A couple of weak upper level disturbances will keep partly to
mostly cloudy conditions in place for overnight into Wednesday
morning. There is even a chance of a few sprinkles or patchy very
light drizzle...mainly along and north of Route 6. Clouds will
decrease from west to east through the daytime hours Wednesday as
a ridge of high pressure begins to build into the Ohio Valley. Low
temperatures Wednesday morning will drop into the lower to middle
40s. High temperatures on Wednesday will rebound into the upper
50s to lower 60s.


Short term...(this evening through wednesday)
issued at 312 PM EDT Tuesday Oct 13 2015

An overall quiet pattern to continue this period with main
forecast challenge centered on sky cover trends/temperatures through late
Wednesday afternoon.

Some patchy very light drizzle persists across portions of far
North Central Indiana/southwest lower Michigan this afternoon. A
weak short wave appears to be departing Northeast Indiana at the
present may see some downward trend in drizzle over next
few hours...although lake effect/enhancement may keep at least
some patchy light drizzle going through late afternoon. The next
upstream short wave associated with a 130 knot upper jet streak
should move into local area late afternoon/early evening...placing
the area for a brief time in left exit region of this jet streak.
Have had a few upstream reports across western/central Wisconsin
of some very light rain/drizzle/sprinkles with this feature and
have continued scattered sprinkles mention across the north this
evening. Yet another weak reinforcing surface trough with this feature
should track through the area late tonight resulting in more
veered north- northwest low level flow early Wednesday morning.
This could prolong some patchy light drizzle downwind of Lake
Michigan Wednesday morning for favored lake effect areas...but
will keep mentionable probability of precipitation out of the forecast due to
meager...shallow based moisture profiles.

Larger scale synoptic subsidence to become favored from west to
east during the day Wednesday which should eventually erode any
lingering stratocu. Some reinforcement to low level thermal
troughing due to aforementioned surface trough passage late tonight
may provide slightly cooler low level thermal profiles for
Wednesday...although this should be offset by some insolation and
slightly better afternoon mixing. Thus...have maintained high
temperatures on Wednesday fairly close to that of today...perhaps a few
degrees warmer across the north. Northwest winds will be
noticeably weaker on Wednesday...generally in the 10 to 15 miles per hour


Long term...(wednesday night through tuesday)
issued at 312 PM EDT Tuesday Oct 13 2015

Focus of long term is on thursday's cold frontal passage and
subsequent sharp cool down for the weekend. Still not particularly
impressed with our rainfall chances. Models continue to struggle
with exact track/configuration of midlevel shortwave set to swing
through the central Great Lakes but latest runs show little more
than a shear vorticity maximum with weak/ill-defined low level
convergence along associated cold front. Similarly...moisture
advection is highly limited with little to no change in low level
Theta-E as winds remain almost due westerly. Have therefore kept
probability of precipitation/quantitative precipitation forecast tempered with the best chances north of US-30.

Cold air advection will arrive in stages with more formidable push actually not
arriving until late Friday. This combined with relatively deep
mixing heights will keep highs in the middle to upper 50s on Friday.
Much colder conditions then expected on Saturday as 850mb temperatures
approach -5c. Fair amount of stratocu expected and highs for most
locations may struggle to get out of the 40s. Some patchy frost
possible Saturday morning if clouds scatter and winds die down in
time. Much better chance for widespread frost/freeze conditions
Saturday night as surface high moves directly overhead. Still cant
rule out a Few Lake effect rain showers in our northwest given
building lake-induced instability. However...latest GFS forecast
soundings and trajectories paint a much less favorable picture
with more of a northwest flow scenario and a much drier
environment. Kept slight chance in our Michigan counties
Friday/Friday night but this may be removed if GFS verifies.

Cold snap will be short-lived as progressive wave exits and
southwest flow returns early next week. Expect temperatures near to above
average for at least the first half of the workweek.


Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 752 PM EDT Tuesday Oct 13 2015

Initially VFR ceilings early tonight...though upstream low level cold
pocket at 06 UTC across southeastern WI bodes favorably for ceilings to lower
somewhat few hours either side of sunrise. Maintain at or above
critical levels...though concede some chance that ksbn might dip
briefly into fueling/alternate criteria...with later iterations to


Iwx watches/warnings/advisories...
Lm...Small Craft Advisory until 11 am EDT Wednesday for lmz043-046.



short term...marsili
long term...agd

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