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Area forecast discussion 
National Weather Service northern Indiana
114 am EST Thursday Nov 26 2015

issued at 112 am EST Thursday Nov 26 2015

High pressure off the eastern seaboared and a cold front slowly
approaching from the west will bring mild conditions along with an
increasing probability for rainfall for the first part of the
Holiday weekend. It will be warm today with highs in the middle to
around 60. Lows tonight will hold in the upper 40s to lower 50s.
Cooler...more seasonable air...along with drier conditions will
filter in for the latter part of the weekend.


issued at 836 PM EST Wednesday Nov 25 2015

Backed probability of precipitation off further with likely probability of precipitation now confined to closer to
morning following trends of upstream radars and western offices. A
few spots have reported some sprinkles or a very light
rainshower...but given surface dewpoint depressions still 10 to 15
degrees or locally more will take more time to saturate and even
as they do surface temperatures will be increasing keeping a similar spread
until deeper moisture arrives. Quick look at 00z kilx sounding
shows top down saturation is underway with much of a dry column
now becoming somewhat saturated with dry air still remaining below
the inversion in the lowest couple thousand feet. Given little in
the way of substantial increase in radar returns suspect the
process will be rather slow across our area with high res models
still suggesting best chances remain west. However...with one or 2
sites seeing measurable rain (hundredth or 2) can't just go dry
with at least some potential of very light but measurable precipitation
in the west.

As for the fog...even with The Pocket of light rain well to the
west no indications of fog thus far and with a 10 to 15 miles per hour wind
enough mechanical mixing should exist to keep fog from forming.
Have removed all mention through 12z as did my neighbors to the


Short term...(this evening through thursday)
issued at 244 PM EST Wednesday Nov 25 2015

Clouds beginning to increase as initial short wave moves through
the region this evening. Lower levels remain quite dry and not
expecting any precipitation until late this evening when deeper moisture
and low level jet increase. Theta-E surge rapidly invades the west
after 03z as 925-850mb winds crank to around 50 knots. Not much
upper support but low level convergence and moisture flux should
be enough forcing for saturation and light rain development which
will then move northeast. Have increased probability of precipitation over northwest third
of area but allowed southeast to remain dry with increasing
clouds. Lows tonight may fall this evening with partly cloudy
skies and evaporative cooling later but still expect mild mins in
the middle to upper 40s with warmest readings west.

Increasing low level moisture/precipitation over relatively cold
ground and any remaining snowpack should help areas of fog to form
overnight as well. Warm temperatures today certainly helped eliminate a
lot of the snowpack but warm moist air over the colder residual
ground should still allow some fog development in the north and

Abundant moisture will be in place on Thanksgiving with a cloudy but
warm day. Precipitation chances remain highest northwest closer to upper
trough and low level moisture and forcing. Again no strong middle or
upper level support for widespread rain. Despite clouds and any
rain...temperatures will be very warm with strong southerly flow
pushing temperatures well into the 50s and likely flirting with 60 in the


Long term...(thursday night through wednesday)
issued at 244 PM EST Wednesday Nov 25 2015

Positive tilted trough and attendant frontal boundary will push across the lakes
to start this period Thursday night-Fri. Vigorous low level jet and associated
moistening/Theta-E surge warrant a slight uptick to probability of precipitation
west/widespread moderate quantitative precipitation forecast event.

12z guidance across the board took a sig shift South West/frontal zone
placement this weekend west/12z European model (ecmwf) alone as a northern outlier. 00z run
west/closer to broad consensus of frontal zone stalling in vicinity of the Ohio River
and secondary frontal wave developing through Kentucky into sun which keeps rain
shield out of County Warning Area. Thus followed a modified superblend approximation
cutting all but far south early Sat.

Laggard rockies cutoff to eject out Erly next week...allowing stalled
Ohio River frontal zone to surge back north into the southern lakes. Will hold
close west/prior grids given good agreement W/consensus. Otrws temperatures
through the period near normal.


Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1251 am EST Thursday Nov 26 2015

Sig changes with respect to 06 UTC tafs. First given strong/near steady-state
ramped sswrly flow across northern Indiana for entirety of
forecast period. While some oscillation in severity inevitable
with afternoon lull possible with slightly better mixing/momentum
Transfer...especially at kfwa...magnitude of 2kft above ground level flow
suggests maintaining mention throughout. Also have shied away from
prior IFR dominant conditions for daytime at ksbn per latest hrrr
analysis with suggestion of fleeting IFR conditions late morning
coincident with upstream frontal wave cyclogenesis and focused
moisture transport/surge. Will still need to monitor as widespread
dz/rain into northwestern in would raise potential for IFR as a more
probable outcome.


Iwx watches/warnings/advisories...
Lm...Small Craft Advisory until 11 PM EST this evening for lmz043-046.



short term...Lashley
long term...T

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