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fxus63 kiwx 171146 

Area forecast discussion
National Weather Service northern Indiana
646 am EST sun Nov 17 2019

issued at 350 am EST sun Nov 17 2019

Increasing clouds and below normal temperatures can be expected
today with afternoon high temperatures from the upper 30s to low to
mid 40s. There is a slight chance of light rain this afternoon with
a better chance this evening across southwest lower Michigan and
Northwest Indiana. Patchy drizzle will be possible overnight as
this system slowly tracks across the area. Low temperatures
tonight will range from 30 to 35. A slight chance of light rain or
light drizzle may extend into Monday with high temperatures once
again in the upper 30s to mid 40s.


Short term...(today and tonight)
issued at 350 am EST sun Nov 17 2019

Overall, only limited changes needed to the forecast this cycle.
Primary forecast challenge continues to center on chances for
light precip this afternoon and tonight. Water vapor imagery early
this morning indicating disjointed upper level troughing from
southern Manitoba to the Central Plains. Stronger upper
circulation appears to be centered across Nebraska Panhandle, and
this vort Max will track east-southeast this afternoon. As this
vort Max tracks southeast today, mid/upper level deformation axis
to the north across the mid MS valley will only slowly shift
eastward this afternoon into this evening. Advective forcing ahead
of this upper troughing could yield some light rain this
afternoon, but initially dry subcloud layer still provides low
confidence and will limit pops to slight chance. Best chance of
measurable rain should be later this evening across the west as
the upper trough/deformation axis slowly approaches the western
Great Lakes.

Advective forcing should be strong enough to support primarily
liquid precip type this evening. Mid level moisture should become
more limited late this evening overnight with possibility of precip
transitioning to some patchy drizzle. Given advective trends and
abundant cloud cover, have bought in on idea in some guidance of
some upward trend in temps/dew points tonight which would keep sfc
temps in low-mid 30s. Possible exception could be across the east
where thicker cloud cover may be more delayed due to slow
progression of the deformation forcing. With such marginal sfc temps
and low confidence in measurable precip overnight, have primarily
kept chance mention of drizzle as opposed to freezing drizzle. No
impacts are expected at this time.


Long term...(monday through saturday)
issued at 350 am EST sun Nov 17 2019

Another wave progressing through upstream ridge will track across
the southern Great Lakes on Tuesday. A brief increase in depth of
mid level moisture is expected in diffluent flow aloft with the
approach of this wave, but any deeper moisture profiles will be
short lived. Did keep just some slight chance pops of light
rain/drizzle across the north on Tuesday to account for this wave.
Temps to remain well below normal in the upper 30s to mid 40s for
Monday and Tuesday due to the reinforcement of this negative
upper height anomaly/low level thermal troughing.

Mid level ridging should build into the region by Wednesday as
longwave upper troughing digs across southwest Continental U.S. And a
positively tilted upper trough tracks across south central Canada.
A period of better low level warm/moist advection will overspread
the area in advance of these features for Wed and Thu with highs
well into 40s on Wed and into the 50s for most areas on Thu.
Strength of advective forcing, interaction of subtropical/polar
jets, and strengthening low/mid level confluence associated with
these two systems supports categorical rain mention for Wed night
into Thu. Pwats on the order of 1+ inches should have at least
brief residence time across local area late Wednesday into early
Thursday. Conditions will dry out later Thursday night as the
northern stream trough departs, but then will have to monitor how
the southern stream trough ejects for late week and northward
extent of any associated precip chances. Southward track of this
upper wave should keep temps below normal for days 6-8.


Aviation...(for the 12z tafs through 12z Monday morning)
issued at 638 am EST sun Nov 17 2019

A high pressure system was north of the area and helping to keep
a dry east flow over northern Indiana. Patchy ground fog had
developed over northern Indiana overnight, but is not expected to
affect the terminals. The fog will lift after daybreak, with VFR
conditions continuing until late in the taf period ahead of the
next system. It looks like MVFR conditions will spread over the
sbn terminal after midnight. For now, went with 09z with the
arrival of MVFR clouds.


Iwx watches/warnings/advisories...


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

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