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Lawrenceville Weather

Area Forecast Discussion

FXUS63 KIWX 032018

Area Forecast Discussion
National Weather Service Northern Indiana
318 PM EST Sat Dec 3 2016

Issued at 1138 AM EST Sat Dec 3 2016

Cloudy, cool, and mainly dry conditions will persist through
Sunday morning. Highs both this afternoon and on Sunday will reach
the mid to upper 30s, with lows tonight near 30 degrees. An area
of light snow, mixed with rain, will move through the region
Sunday afternoon into Sunday evening. Precipitation should mainly
fall as snow northwest of U.S. 24, and mainly as a mixture of
rain and snow to the south. Some light accumulation of snow may
occur on grassy surfaces. The early portion of next week will
trend a little warmer with rain possible later Monday night into
Tuesday. Some snow may once again mix in. A strong cold front then
brings cold air and chances for lake effect snow for the second
half of the upcoming work week.


.SHORT TERM...(This Evening through Sunday)
Issued at 315 PM EST Sat Dec 3 2016

Quiet and dry night in store for the area with mostly cloudy skies
as high pressure slides to the east. Once again expect cloud cover
to keep temps warmer than guidance and have used consraw which has
been performing quite well. 

Fast moving short wave to move across region Sunday with quick shot
of precipitation from late morning into early evening. Models have
slowed onset by a few hours but still think leading edge of pcpn
will arrive in western areas by mid morning and move into eastern
areas by mid afternoon. Good moisture flux spreads north ahead of
short wave with period of good system relative isentropic lift
coincident with best omega ahead of wave. 

Precipitation type remains tricky with cold air aloft sufficient for
ice nucleation and snow but boundary layer temps warming to mid 30s
central and north and upper 30s southeast. Expect to see primarily
light snow over far north and northwest areas with a chance for rain
to mix in during afternoon. Southeast may begin as snow but
transition to primarily rain. Any accums still look to be around an
inch or less in the north and mainly on grassy and elevated
surfaces. Surface wet bulb temps remain just above freezing and with
roads above freezing not expecting many impacts. Could see a little
better window for the accums by late afternoon and early evening
before pcpn ends as sun angle declines and boundary layer cools a
few degrees.  


.LONG TERM...(Sunday Night through Saturday)
Issued at 315 PM EST Sat Dec 3 2016

...Much colder weather and lake effect snow still on track for
later this week...

Prior to arrival of first shot of arctic air for the season...we
have to deal with a rather potent short wave lifting out of
southwest CONUS late Monday night and Tuesday. Models continue to
handle this energy differently with 12z NAM trending stronger and
further northwest...placing more moisture across our area with
colder air and potential for significant snow accums. However...most
other model guidance remains weaker and further east with energy as
short wave gets absorbed in southwest flow aloft. This solution
worth watching as we do see these ejecting systems often lift out
stronger and further west but without any support at this time will
continue with ensemble approach and weight toward GFS and ECMWF.
This should spread mainly rain into the southeast Tuesday with
possible mixed precipitation at onset along the northwest periphery
of pcpn shield with evap cooling processes. Little accums expected
at this time but that could change with any additional trends

Colder air will start to bleed in Tuesday night and Wednesday with
bulk of arctic air set to arrive Wednesday night and Thursday. This
will get the lake effect machine going in earnest and likely
continue into Friday. Instability will be on the extreme side with
sfc to 700mb delta Ts pushing 30 and 0-2km delta theta-e values
dropping to nearly -6 C/km. Usual concerns this far out center
around moisture depth and trajectories along with DGZ height. Latest
guidance continues to indicate at least favorable conditions for
measurable pcpn and accumulating snow but much too early to nail
down amounts or locations other than broad brush the usual favored
snow belt region. Continue to monitor forecasts as the week
progresses and details become more clear.

Entire area to experience the coldest air of the young winter season
with lows into the teens and highs only in the 20s outside of lake
effect belt. Some single digit lows would not be out of question
with timing of clearing...snowpack and light winds late week.  


.AVIATION...(For the 18Z TAFS through 18Z Sunday Afternoon)
Issued at 1138 AM EST Sat Dec 3 2016

Outside of a stray flurry/sprinkle this afternoon expect dry
conditions to prevail. Overcast stratocu deck will likely remain
in place through the TAF cycle under strong inversion. Cigs will
continue to generally range between 2500 ft and 4000 ft.
Precipitation and VIS restrictions likely overspread the terminals
shortly after 18z tomorrow. 




SHORT TERM...Lashley
LONG TERM...Lashley

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