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Area forecast discussion 
National Weather Service northern Indiana
543 am EDT Friday Aug 29 2014

issued at 509 am EDT Friday Aug 29 2014

A warm front will lift northeast into the area today into this
evening bringing increasing chances for showers and
thunderstorms...especially later this afternoon and evening across
Northwest Indiana and southwest lower Michigan. Highs this
afternoon will reach the lower to middle 80s. Saturday will feature
better chances for thunderstorms and locally heavy rainfall as a
low pressure system tracks into the Great Lakes region.


Short term...(today and tonight)
issued at 509 am EDT Friday Aug 29 2014

A Central Plains shortwave will open northeast into Iowa/southern Minnesota/WI
by later today-tonight. Southwest flow ramp up in advance of
attendant weak surface reflection/trough should support NE mix of surface
warm front/instability gradient into mainly in/Michigan zones by later
today-tonight. May see a few light showers/sprinkles associated
with leading warm air advection arm clip our northwest in/SW lower Michigan counties this
morning. Kept probability of precipitation low (15-25%) as more focused moisture
convergence takes place well north-northwest of the local area.
Stable/subsident airmass on west-northwest periphery of low-middle level ridge
should keep most locations dry for most of the day
otherwise...with broken middle-high cloud canopy and southeast low level
trajectories likely keeping highs in check (upper 70s to middle

Chances for scattered convection will increase middle afternoon into
early evening mainly west of the Interstate 69 corridor as height
falls begin to overspread warm front and what should be a
moderately unstable environment along it. Torrential
downpours/lightning will be the primary concerns as precipitable waters
approach 2". Convective coverage/chances diminish tonight behind
primary Theta-E surge...with moisture channel/surface trough
associated with aforementioned middle level wave remaining west of
the local area through 12z Sat.


Long term...(saturday through thursday)
issued at 509 am EDT Friday Aug 29 2014

Reluctant to make sig changes in light of missed kilx 00utc radiosonde observation and
NAM spacicity with respect to precipitable water/fgen/div fields...instead favoring
consistency with strong nod to a conceptual focused forecast. Deep Gomex
feed with monsoonal tap as western Kansas vortex lifts/opens northeastward into
western Great Lakes by Saturday. This should afford wide precipitable water stream
of near 2 inches from Ozarks northeastward through County Warning Area into Michigan thumb.
Southeast periphery of middle tropospheric height fall centroid still
affords 20-40m/12 hour to County Warning Area. Rich Theta-E plume affording tall/thin
cape profiles amid deep parallel flow profile with mbe velocities
typically at or below 8 kts still raises flag for heavy rafl potential
Sat/Sat night despite meager Middle Range model solutions/qpf.
Favorable jet dynamics with low level jet feature to track up Ohio River
valley Sat night may also factor into mesoscale convective system maintenance as well.
Additional injection of overtaking northern stream presently moving
eastward through northestern Montana may also Foster regenerative convection.
Potential for heavy rainfall/flooding/repetitive track complexes
remains a concern...albeit quite nebulous in any spatial/temporal
detail and any further stress than severe weather potential statement/heavy rafl mention would be
premature. Removed probability of precipitation Sunday night with frontal boundary
stall/lysis and shortwave ridging lending no appreciable focus.
Remaining concern lies with Monday as severe weather potential appearing
less attractive with next shortwave liftout through broad western
Canada/northern plains trough. Energy lifts well northwest of County Warning Area in light
of deep negative trough axis tilting in deference to downstream
ridging fostered by strength of southeastern states subtropical ridge. Will
side with consistency but focus hiest probability of precipitation northwestern County Warning Area with greater
gradient to Middle Range chance probability of precipitation east. By Tuesday evening expect
frontal boundary to lay out into Ohio Valley and best kinematics
racing well northeastward into ont/Quebec and again side with no sensible weather for
remainder of forecast. Gradual moderating temperature trend starting middle
week amid gradual height rebound surface/aloft.


Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 543 am EDT Friday Aug 29 2014

Mainly VFR through the taf cycle. High based/VFR isolated
showers/sprinkles will be possible early this morning at ksbn as
initial 850 mb Theta-E push lift through. Drier low level
environment farther removed from weak low level jet support should help keep
kfwa mainly dry through at least middle afternoon. Shortwave opening
northeast toward Iowa/southern Minnesota will allow primary surface warm
front/instability gradient to mix north into northern Indiana
later this afternoon-evening. This feature will bring increasing
chances for showers/storms with it...although confidence/coverage
remains too low for any point mention at this forecast range.


Iwx watches/warnings/advisories...


short term...steinwedel
long term...Murphy

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