Area forecast discussion
National Weather Service northern Indiana
445 am EDT Tuesday may 21 2013
Synopsis...
issued at 440 am EDT Tuesday may 21 2013
Shower and thunderstorm chances will continue to increase through
Wednesday...with a few showers possibly lingering into Thursday.
Drier and cooler weather is anticipated late this week into next
weekend.
&&
Short term...(today and tonight)
issued at 442 am EDT Tuesday may 21 2013
Outflw dominant convn continues to progress slowly across
western portion of County Warning Area this morning yet continues to fester within as yet
fvrbly unstable ll Theta-E ridge. However upstream stratiform across western
in/eastern Illinois decaying rapidly west/warming cloud tops noted in infrared and
Marks expected rapid eastward downtrend through daybreak.
Stabilization occurring in wake of this line and suspect little if any
redvlpmnt in the cards until very lt this afternoon/early evening in association/west
eastward translation of surface low into NE WI by 00z. However northward redvlpmnt of
preferred ll Theta-E ridge likely delayed to well after dark timed
west/northward expansion of low level jet tied to ejecting conv induced SW trough out
of OK. Thus delayed overnight ramp to prior probability of precipitation toward window of
greater model consensus implied forcing after midnight.
Inbtwn expect clouds to scattered out by lt morning/early afternoon west/another very
warm day in store per modest mixing within ll thermal ridge.
&&
Long term...(wednesday through monday)
issued at 442 am EDT Tuesday may 21 2013
An upper low will lift northeast Wednesday...accompanied by a cold
front. The right entrance region of an upper level jet will pass
over the southeast portion of the forecast area Wednesday including
most of Northwest Ohio. However...given very limited cape and a rather
unidirectional wind profile...current thinking is severe storm
potential is marginal. Much cooler air will spread into the area
behind the cold for late this week. Favored the GFS mean ensemble
MOS which has been generally trending a little colder late this
week...otherwise...has been consistent for the past few 00z runs.
Kept the forecast dry after Thursday as an upper level ridge builds
upstream.
&&
Aviation...(for the 06z tafs through 06z Tuesday night)
issued at 442 am EDT Tuesday may 21 2013
Difficult forecast with respect to convective probabilities through
the forecast period and early failure. Amid a strongly divergent
boundary layer axis per visible Sat imagery lying across northestern Illinois/northwestern in
past few hours proving to be strongly detrimental. This despite
moderate surface based instability pool situated across northern
Indiana/Southern Lower Michigan this evening. A well scoured/deeply
mixed environment across northern/central Illinois with putrid
middle/upper 50s dps this afternoon...removes any immediate concern for
initiation next few hours. This immediate upstream environ was
within wake of early afternoon shortwave...that initiated
strong/severe convection midday across yoop/northern lower Michigan.
Eastern fringe of eml environment with 7.5-8.25 c/km middle level lapse
rates to likely keep updrafts in check/isolated remainder of the
evening. Will maintain that any sig chance for convection to be
associated with well upstream convection across east central
MO...with several hour wait until more vigored upstream 925-800 mb wind
field with present focus over the Ozarks/northern Arkansas shifts
northeastward overnight into southern/central Illinois and veers/ramps to
45-55kts...finally nosing into klaf vicinity around 09-12 UTC per
rap/arw...and a significantly poor/laggard hrrr3km recently coming
in line to reality. Sufficient preparatory conditioning of
environment via moisture flux convergence surface-900mb to maintain
MUCAPE pool of 1200-2000 j/kg across forecast area. This should
allow decent maintenance of convective complex with across Missouri
to reach northern Indiana well after midnight into ksbn and near
daybreak at kfwa. Disfavored timing/parcel ascent becoming less
surface based with time and modest deep layer shear to largely
preclude severe potential...though have continued to ack that strongest
cells may approach low end severe limits in severe weather potential statement.
&&
Iwx watches/warnings/advisories...
in...none.
Michigan...none.
Ohio...none.
Lm...none.
&&
$$
Synopsis...skipper
short term...T
long term...skipper
aviation...T
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