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Area forecast discussion 
National Weather Service northern Indiana
417 PM EST Thursday Mar 5 2015

issued at 416 PM EST Thursday Mar 5 2015

Partly cloudy skies will continue into the overnight hours with a
Few Lake effect flurries expected to diminish by evening.
Extremely cold overnight lows will drop to zero to 5 below zero.
High temperatures on Friday will be in the middle to upper 20s.


Short term...(this evening through friday)
issued at 414 PM EST Thursday Mar 5 2015

Rapid eastward exodus of positive tilted middle tropospheric trough through lower
Great Lakes into eastern states followed by lesser amplitude troffing into
western Great Lakes Friday to solidify dry cp Arctic airmass across region
overnight into early Friday. Increases wrly flow upwind of Lake Michigan to
afford dry air entrainment with any lingering flurries succumbing
to demise near sunset followed by rapid longwave radiational
losses. As surface Ridgeline settles into Ohio Valley on Friday and two high
belted clipper systems track well into far southern Hudson
Bay/northern James Bay the other to Lake Winnipeg by 00 UTC Sat.
Extreme dry upstream air mass characterized by 20 percent of
normal precipitable water...lte 0.10 inches throughout Upper/Middle MS valley. Strong
warm air advection surface-925mb along with high early March sun angle/insolation
with near 10c/12 hour rises at 925mb by 21c in southwestern County Warning Area. As such
have gone a bit hir with temperatures tmrw...strong diurnal plus...muted
on eastern County Warning Area along trailing periphery of exiting cold pool.


Long term...(friday night through thursday)
issued at 414 PM EST Thursday Mar 5 2015

The start of the warmup begins during the day Saturday. Do not
expect much of a maximum temperature difference between Saturday and Sunday
as most of the energy will be used to melt snow.
Additionally...another weak shortwave slips across the Great
Lakes during the day Sunday and this will act to temper the warm

The biggest change in temperatures will occur midweek into the
latter part of the extended forecast. Given the frost depth snow
melt will create isolated flooding in low lying area and poor
drainage locations. Will need to closely monitor waterways for
ice jams as the rivers begin to shed ice and flows increase.

No precipitation during the warm-up and thus little contribution
to the water/flow.


Aviation...(for the 18z tafs through 18z Friday afternoon)
issued at 110 PM EST Thursday Mar 5 2015

VFR met conds through the forecast period as upstream Ridgeline
settles through southern Great Lakes and into lower Ohio Valley by daybreak.
Ramped srly surface flow associated with strong warm air advection in
advance of high belted clipper system moving through southern Hudson Bay
late Friday afternoon. Elevated Erly March sun angle to likely afford
mixout of gusts into Lower/Middle 20kts in Erly afternoon.


Iwx watches/warnings/advisories...


short term...Murphy
long term...Lewis

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