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Area forecast discussion 
National Weather Service northern Indiana
1250 am EDT Thursday Aug 28 2014

issued at 1249 am EDT Thursday Aug 28 2014

Fair weather is expected today into Friday morning as high
pressure drops southeast through the Great Lakes region. A low
pressure system and warm front will bring increasing chances for
showers and thunderstorms to the area later Friday into this
weekend. Highs today will reach the upper 70s to near 80...and the
middle 80s on Friday.


Short term...(this evening through thursday)
issued at 321 PM EDT Wednesday Aug 27 2014

Tranquil weather expected this period as high pressure builds through the eastern lakes.
North/nerly ll follow will continue to advt in much drier air west/surface dew points falling
in the 50s tonight. Will tweak temperatures overnight a bit however in light
of upstream eastward spillage of middle/high clouds. Otrws pleasant weather expected to
continue on Thursday.


Long term...(thursday night through wednesday)
issued at 321 PM EDT Wednesday Aug 27 2014

A 500mb ridge expanding northwestward from the southeastern Continental U.S.
Will keep weather quiet Thursday night before more active weather
returns for the weekend. Surface high pressure will linger over
lower Michigan and the Ohio Valley through late Thursday evening before
drifting into the New England states.

Meanwhile...a trough over the southwestern U.S. Today will drift
eastward into the Central Plains and merge with a shortwave crossing
the northern plains by Friday afternoon...then lift northeastward
into northern lower Michigan and southern Ontario by Sunday morning. This
will bring a surface trough and low pressure center across the Great
Lakes region through the weekend.

On Friday...the County Warning Area remains under the exiting high pressure ridge
through the early afternoon. Additionally...the best moisture
transport/convergence focuses along an axis to the north of the County Warning Area
as the center of weak surface low develops over Minnesota/WI/Iowa Friday
morning. Think the ridge will suppress any precipitation for the
first portion of the day. As high pressure exits to the east late
Friday afternoon and evening...the warm front associated with the
surface low lifts northeastward across the Great Lakes. Given weak
isentropic ascent on the 310k surface and 1-2k j/kg of MUCAPE expect
chances for some shower/T storm development.

Saturday into Sunday the main upper level trough/associated surface
low lifts from the Central Plains into Ontario. Best forcing/per
850-500mb qvector convergence and strong isentropic ascent at 305k/
moves through Saturday through Sunday morning. As a result...have
high chance to likely probability of precipitation across the area through this time. Kept
thunderstorms in as well given decent instability...especially for
Sunday afternoon where models suggest upwards of 2000 j/kg of MUCAPE
for the western and south central portions of the County Warning Area. As far as
severe chances thinking they will be fairly limited given weak 0-6
km shear...but the potential for heavy rain is more significant.
With precipitable waters between 1.5 and 2 inches...and corfidi vectors oriented
parallel to the approaching frontal boundary Sat after/Sat evening could
see flooding problems as the front approaches...mainly in the
northwestern and central County Warning Area.

Sunday night a brief ridge aloft will slide into the County Warning Area behind the
exiting shortwave/surface low pressure trough...allowing for a brief
break in precipitation. By late Monday morning...a more potent
trough will aid in the development of a surface low over Minnesota.
This low will lift northeastward into Hudson Bay by Tuesday
morning...bringing a surface trough/cold front across the Great
Lakes region for the start of the work week. Moisture
convergence/strong isentropic ascent at 305-310k are in place Monday
afternoon through late Tuesday have kept the going
higher chance probability of precipitation for that time period. Storms late Monday
afternoon could become severe...with around 1500-2000 j/kg MUCAPE
and 30-50 kts 0-6 km shear over much of the County Warning Area. Kept consensus
chance probability of precipitation in for Tuesday...which will mainly be in the morning
with the exiting front.

High pressure builds in by Tuesday evening under relatively zonal
flow aloft...and will drift across the Ohio Valley through Thursday
night. Both the GFS/European model (ecmwf) have high pressure holding
pulled consensus slight chance/chance probability of precipitation Tuesday night and


Aviation...(for the 06z tafs through 06z Thursday night)
issued at 1249 am EDT Thursday Aug 28 2014

Mainly VFR through the period as light northeasterly winds
gradually veer more easterly with time under surface high pressure
dropping southeast into the lower lakes. Only exception may be
near daybreak at FWA where MVFR stratus/fog may develop.
Otherwise...sct-bkn cirrus canopy today will give way to a broken-
overcast middle level cloud deck tonight.


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long term...mesoscale discussion

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