Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Indianapolis in
1147 PM EST Sat Feb 13 2016
The aviation section has been updated below.
issued at 338 PM EST Sat Feb 13 2016
A cold upper trough over the eastern U.S. Will move on to the east and
a broad upper ridge will build in over much of the U.S. Bringing milder
weather later next week.
But in between there will be a couple of systems which will result in
periods of active weather. The first system is an upper disturbance which
will move our way and bring snow accumulations to most areas Sunday and
Sunday night. A low pressure system over the lower Mississippi Valley
may bring mixed precipitation to southeast sections Monday. Finally an
upper disturbance will bring mixed precipitation on Tuesday and a third
system will bring a chance of rain late next week.
Near term /tonight/...
issued at 955 PM EST Sat Feb 13 2016
Short term model guidance indicates some lift will be moving into the
western zones towards sunrise...but the better lift will probably
hold off until later in the morning on Sunday. Will back off on the timing
of the probability of precipitation in the western zones more towards sunrise Sunday.
Previous discussion follows.
High pressure over Illinois will move quickly to the east as an
area of low pressure moves into the upper Midwest and eventually our
way by late Sunday. Models...especially the NAM bring precipitation
into our area towards morning. Although the NAM may be a bit too
quick..I would not be surprised that snow may develop by then.
Issued a Winter Weather Advisory beginning over western sections
late tonight beginning around 09z.
Temperatures will bottom out quickly this evening and then rise a little late
tonight as warm advection increases. Went with lows from 3 to 5 above over
northeast sections to the middle teens far southwest.
Short term /Sunday through Tuesday/...
issued at 338 PM EST Sat Feb 13 2016
Main focus will be snow amounts followed by temperatures as they
will be critical regarding precipitation type in the 2nd system.
Snow will occur Sunday as strong warm advection occurs and an upper
disturbance approaches from the west. NAM is a bit high on the quantitative precipitation forecast
..while some of the other models are a bit low. Went slightly above
super blend quantitative precipitation forecast and given high snow ratio's on Sunday...central and
southwest sections could see 2 to 3 inches of accumulation...while
northeast areas get 1 to 2 inches. Decided to go with a Winter Weather
Advisory most areas along and west of a Lafayette to Indianapolis and
Greensburg line until midnight Monday morning. Snow will
diminish Monday night and only light accumulations if any expected after
Models indicate lots of low level moisture will remain across our area.
An area of low pressure over the lower Mississippi Valley may bring
slight chance probability of precipitation over southeast sections Monday and Monday evening...but
affects for US will be minimal.
Another system will bring mixed precipitation to most sections Tuesday...but
leaned towards mostly snow north as models may be a bit too warm with low
level temperatures as there will be snow cover from the previous system.
For this reason...also leaned towards the lower end of a model blend on
Long term /Tuesday night through Saturday/...
issued at 237 PM EST Sat Feb 13 2016
A system moving through the area as the long term begins will
bring chances for snow to the north and a mix of rain and snow
south for Tuesday night. Model variability is still fairly high
with exact track of this system and this will make a big
difference in the temperatures profiles which will in turn
determine precipitation type. Thus have played toward a middle of
the Road solution in terms of a mix in the south initially
changing over to all snow late.
The system will exit quickly and broad high pressure builds over
the area to produce dry conditions until Friday. Temperatures
start warming on Thursday into the 40s and Friday looks like 50s
on the back side of the high under southwesterly flow. This warm
moist flow will bring chances for rain back into the area Friday
ahead of a frontal system and keep chances in until after the cold
frontal passage Friday night.
Aviation /discussion for 14/06z tafs/...
issued at 1147 PM EST Sat Feb 13 2016
VFR into the overnight...with conditions quickly deteriorating to
MVFR and then IFR in snow Sunday morning through the day.
Expect snow to develop in the 12-14z time frame across the
area...with a period during the afternoon of fairly intense snow
with 1/2sm visibilities and freezing fog possible. Snow will begin
to taper to snow showers late tomorrow afternoon into the
evening...although IFR ceilings may remain.
Winds will be light and variable early...becoming more southeasterly
and pushing 10-15kt tomorrow.
Winter Weather Advisory from 8 am Sunday to midnight EST Sunday
night for inz029-036-037-045>047-053>056-062>065-070>072.
Winter Weather Advisory from 4 am Sunday to midnight EST Sunday
night for inz028-035-043-044-051-052-060-061-067>069.