Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 041145

Area Forecast Discussion
National Weather Service Northern Indiana
645 AM EST Mon Dec 4 2017

Issued at 630 AM EST Mon Dec 4 2017

The warming trend will continue today with highs this afternoon
into Monday will climb into the upper 50s and lower 60s. There may
be a brief shower over southwest Lower Michigan and northwest
Indiana today, however the bulk of the rain will hold off until
later tonight. Rain, gusty winds, and even a few thunderstorms
will move in tonight as a strong frontal system sweeps through the
region. Wind gusts up to 40 mph are possible tonight and again
Tuesday afternoon. Temperatures will fall into the 30s by mid
Tuesday afternoon. For the rest of the week, expect continued cold
temperatures with some lake effect snow. Highs will only reach
into the upper 20s to lower 30s for the latter half of the work


.SHORT TERM...(Today and Tonight)
Issued at 437 AM EST Mon Dec 4 2017

Intense amplification to flow pattern as extreme intermountain
wave/pvu anomaly rotates around/under southward descending wave
through Manitoba. Strong agreement with respect to timing/location
of resultant plains cycle/frontogenesis with 6-8 mb/6 hr deepening
through today. Prior early am update addressed potential for
influence/brief shra associated with weak lead shortwave to graze far
northwest CWA, but then otherwise low level condensation pressure
deficits remain stoic until evening onslaught of best
dynamics/eastward sweep through the western Great Lakes. Very strong
frontal zone with cross isallobaric differential on order of 14mb/3
hrs. Strong wind gusts with 2kft prefrontal wind flow on order of 60-
70kts to aid forced parcel ascent in dwindling MUCAPE core as it
progresses west to east through CWA, initially 600-900 j/kg nw 00
UTC Tue trailing to less than 200 j/kg 09 UTC Tue over far eastern
CWA. Continued slight chance mention of TSRA tonight with coverage
likely sparse/sporadic/fleeting in nature. Wind field and guidance
suggesting just under wind advisory criteria with bulk of gusts
tonight in 35 to 40 mph range, but certainly would not rule out
higher outliers associated with shallow convective cells.


.LONG TERM...(Tuesday through Sunday)
Issued at 437 AM EST Mon Dec 4 2017

Magnitude/depth of cold air mass behind front continues to increase
with consistency noted in affording falling temps/max t held to
hourlies on Tue. Effective dry slotting and steep/shallow surface
based lapse rates support between L1/L2 momentum transfer and
afforded some increase/detail with respect to gusts DY2. Strong
westerly flow may prove detriment with respect to initial LES setup
Tue night/Wed. Significantly more veered/homogeneous flow with in
cloud bearing flow supports higher pops as well as farther inland
intrusion/southward extent. Several variances beyond with respect to
additional northern Canadian vorticies and disruptions into mean
James Bay into western Great Lakes trof. Continued hint of clipper
system diving into Lower Ohio Valley late Friday night.
Disruption/backing of flow over southern Lake Michigan expected,
though resumption of at least some LES response through the weekend
over northwest CWA appears likely. In collaborative effort have
lowered temps from Wed through the weekend, especially max temps,
nudging towards consraw. as longwave pattern remains in place
with 120W ridging and persistent Hudson Bay/Great Lakes centered


.AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning)
Issued at 632 AM EST Mon Dec 4 2017

A strong cold front will approach the terminals today with winds
increasing. Given good mixing throughout the day, left low level
shear out. Adjusted the timing of showers and lower CIGS to
coincide with the katabatic FROPA. Given the nature of the front,
clouds are not expected to linger. Conditions should become VFR
by the end of the TAF period.


LM...Small Craft Advisory until 4 PM EST this afternoon for LMZ043-

     Gale Warning from 4 PM this afternoon to 7 AM EST Wednesday for



LONG TERM...Murphy

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