Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 110523
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
123 AM EDT Fri Aug 11 2017

.SYNOPSIS...
Issued at 118 AM EDT Fri Aug 11 2017

A cold front will move through the region early today with
chances for showers and a few thunderstorms. Otherwise, mostly
cloudy skies early morning lows in the lower to middle 60s. Highs
later today will be in the upper 70s to lower 80s. Drier and
cooler conditions then return this weekend into early next week.

&&

.SHORT TERM...(This Evening through Friday)
Issued at 223 PM EDT Thu Aug 10 2017

The main focus into tonight and Friday will be on rain/thunder
chances as a seasonably strong closed low tracks east into the
Northern Great Lakes forcing a cold front into the local area.
Convective initiation is expected near this frontal boundary across
nrn IL/srn WI late this afternoon on the nose of a 50 kt mid level
speed max. This weak DCVA/forcing and fold over of leading low level
theta-e gradient (within a 25-30 kt LLJ) overspreads nw IN/sw Lower
MI this evening into the early overnight. This may be enough to
allow the upstream line of showers/thunder to survive ese into
these areas 01-05z. Raised PoPs and added thunder but not much of
a severe threat (SPC has a marginal risk for hail/wind in
LaPorte/Berrien counties) expected as activity outruns better
support/shear and boundary layer cools. A few lingering showers
could continue near this outflow into the rest of the area later
tonight.

The main cold front and trailing low amplitude shortwave energy
ejecting east out of the Rockies/High Plains will swing through from
west to east tomorrow bringing continued chances for isolated-
scattered showers in the morning mainly along/south of US 24. Low
level moisture immediately along the front not all that impressive
for August (sfc dewpoints low-mid 60s), but sufficient to generate
up to near 1000 j/kg of MLCAPE Friday afternoon under cool
cyclonic flow aloft. This is dependent on cloud cover but may be
enough to trigger a few thunderstorms by Friday afternoon into ne
IN/sc Lower MI/nw OH. Any updrafts will likely have 30-40 knots of
deep layer shear to work with, though cloud contamination/meager
lapse rates/weak convergence near boundary should limit the severe
risk to an isolated strong storm at best.

&&

.LONG TERM...(Friday Night through Thursday)
Issued at 223 PM EDT Thu Aug 10 2017

A return to below normal temperatures, low humidity, and mainly dry
conditions will be the story this weekend into early next week as
drier air filters in post-frontal. There will be a series of lower
amplitude/sheared shortwaves to move through in wnw flow aloft
Saturday through Monday. Each wave could bring some occasional
cloudiness and non-zero rain chances, though chances in any one
period appear too low for a mention given timing difference in model
guidance and lacking moisture. Dry with some warming then toward the
middle of next week as upper level ridging overspreads.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
Issued at 116 AM EDT Fri Aug 11 2017

Upper level jet support from the left exit region was helping to
sustain a few clusters of storms early this morning. The activity
has moved east of SBN, but showers and an isolated storm are
possible at FWA early this morning. For now, have mentioned
vicinity showers at FWA, but included VCTS later today there from
16-23Z when diurnal heating combines with frontal support.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SYNOPSIS...Murphy/Skipper
SHORT TERM...Steinwedel
LONG TERM...Steinwedel
AVIATION...Skipper


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