Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service northern Indiana
551 am EDT Wednesday Apr 16 2014

issued at 349 am EDT Wednesday Apr 16 2014

Today into Thursday will feature moderating temperatures and dry
conditions as winds become southerly. Highs should reach near 50
degrees today...and near 60 degrees Thursday. A frontal boundary
will move across the region late Thursday night and Friday
bringing increasing chances for rain showers. Drier and slightly
cooler weather is expected on Saturday as high pressure builds


Short term...(today and tonight)
issued at 349 am EDT Wednesday Apr 16 2014

Fair weather and start of a moderating trend anticipated this period as
low level flow becomes southerly. This warm air advection regime will occur as
high pressure shifts east of the area and a potent middle level
trough in flatter flow translates east into the upper Midwest.
Southeasterly winds at the surface should result in a somewhat shallow
mixed layer to near 875 mb today...with highs likely making a run
at 50f (still around 10 degrees below normal for middle April
standards). More opaque middle/high level cloud cover and any precipitation
with the aforementioned upper trough will pass northwest of the
iwx County Warning Area tonight.


Long term...(thursday through tuesday)
issued at 349 am EDT Wednesday Apr 16 2014

Fairly quiet long term period with several weak short waves and
associated precipitation chances with each. First short wave will move
through the western lakes Thursday with a weakening cold front
moving into our area. Moisture limited initially with weak
forcing so expecting just an increase in middle level clouds during the
day near the front as it stalls across the County Warning Area. A second short wave
will move through the mean flow with a weak surface wave along the
boundary Thursday night into Friday with a little better moisture pooling
along front. This supports middle chance probability of precipitation with quantitative precipitation forecast amounts looking
generally less than a quarter inch.

Surface high and short wave ridging to move back in later Friday and
continue into Sunday. Temperatures initially below normal with cool
northerly flow as high moves across the western Great Lakes Saturday.
Trajectories off the lake will support even cooler temperatures near the
Lakeshore at times. Temperatures on Saturday expected to remain in the 50s
for most of the area. Return flow develops on Sunday as high slides
east. European model (ecmwf) considerably warmer than GFS with support from Gem.
925mb temperatures mixed support warmer temperatures than most consensus blends
and closer to HPC guidance. Amount of cloud cover ahead of next
short wave approaching for later Sunday night into Monday will
really dictate how warm temperatures climb Sunday afternoon but leaned a bit
higher than allblend with all areas into the 60s Sunday. Southern
areas could flirt with 70 with less clouds and good mixing.

The next short wave and weak surface front approaches late Sunday
night into Monday. Models appear to have slowed this wave down a bit
with precipitation chances on Sunday looking slim and confined to far north
ahead of front. Have trended probability of precipitation back with slight chance mention across
the north in the afternoon. A little better chance Sunday night and
Monday with front in the area. Confidence low on timing and strength
of this system at this range with model disparity so low probability of precipitation
continue with temperatures near normal. Potential for another decent warmup
just beyond day 7 for the middle to end of next week as a strong
system looks to organize in the central Continental U.S..


Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 550 am EDT Wednesday Apr 16 2014

VFR conditions and only a gradual increase in middle/high level
clouds expected this period with dry Continental polar airmass in
place. Light/variable winds under surface ridge early this morning
will become southerly at 10-15 knots (gusts up near 20 kts) today
in advance of a developing upper Midwest low pressure system.


Iwx watches/warnings/advisories...


short term...steinwedel
long term...Lashley

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