Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kiwx 241907 
afdiwx

Area forecast discussion
National Weather Service northern Indiana
307 PM EDT Wed may 24 2017

Synopsis...
issued at 306 PM EDT Wed may 24 2017

Showers and isolated thunderstorms are expected late this
afternoon into tonight. Some areas could see more than an inch of
rain, which could lead to flooding in already saturated
agricultural areas and along rivers. Thursday will feature cloudy
and cool conditions with lingering chances for rain showers. Lows
tonight will drop into the 50s, with highs tomorrow only
recovering into the 60s. Warmer temperatures and periodic low
chances for rain showers then Friday into the Holiday weekend.

&&

Short term...(this evening through Thursday night)
issued at 306 PM EDT Wed may 24 2017

Continued expansion of showers/storms can be expected this
afternoon/early evening as forcing and deep moisture transport
(associated with shortwave and strong left exit jet support) lift
northeast into the Ohio Valley on the eastern fringe of an
unseasonably deep upper low dropping southeast through Missouri.
Locally heavy rainfall and better chances for thunderstorms will
be confined to our NE in/NW Ohio counties where low level front
strengthens and nearly 1000 j/kg of SBCAPE resides. Lacking
shear/flow and meager lapse rates should preclude much of a severe
threat. The bigger concern will be the potential for localized
heavy rain/flooding, especially near the I-69 corridor.

The aforementioned shortwave/jet will help re-focus the main
circulation center to near Cincinnati by later tonight...then
gradually broadening east towards the mid-Atlantic/Appalachians
Thursday into Thursday night. Developing trowal/deformation forcing
on the northern fringe will keep periods of rain in the forecast
into tonight. The strongest forcing will continue to focus into NE
in/NW Ohio where highest pops/quantitative precipitation forecast were retained. Waning diurnal
instability should bring down the intensity in showers with little
in the way of embedded thunder anticipated mid evening into the
overnight. This will also lead to some constriction/narrowing of
the banding in our area with heavier rainfall more likely to focus
off the SSE (more across east-central/se in) near main vort
center.

Thursday will feature cool/cloudy northerly flow on the backside of
the increasingly stacked low. There may also be enough lingering
deformation/moisture and some diurnal heating to generate
additional showers mainly along/east of I-69 during the day.
Brief ridging through the column then brings fair wx Thursday
night into Friday morning.

&&

Long term...(friday through wednesday)
issued at 306 PM EDT Wed may 24 2017

A brief transition to a flatter/more zonal flow pattern is expected
Friday into Saturday. A small scale/convectively aided perturbation
embedded in this flow (near a developing instability axis) will be
the main feature to watch for a period of rain/thunder later Friday
into early Saturday. The compact/low amplitude nature of this
feature is reeking havoc on models with confidence in timing/track
of associated precipitation below normal at this forecast range. As
a result will continue to accept blended chance pops. Mainly dry and
warmer otherwise.

The next/more pronounced shortwave in strengthening west-southwest
flow may bring another convective complex through the local area
Saturday night/early Sunday as an upper trough amplifies into the
upper Midwest. Good surge of moisture/MUCAPE embedded in this
strengthening southwest flow may present a heavy rain/severe
weather threat as frontal boundary briefly lifts back in. Upper
troughing then becomes better established into the Great Lakes
region Sunday into next week resulting in cooler temperatures and
periodic chances for showers (mainly diurnally driven) as additional
shortwave energy pivots through.

&&

Aviation...(for the 18z tafs through 18z Thursday afternoon)
issued at 151 PM EDT Wed may 24 2017

VFR conditions for the first part of the taf period, then a
gradual decline to MVFR/IFR as precipitation moves in. Expect
showers and perhaps a few thunderstorms at ksbn this afternoon
before more substantial rain moves in after 21z. Did not feel
confident including thunderstorms in the vicinity in the taf yet...but will monitor closely
as things develop. Otherwise, expect a period of more steady rain
this evening and continuing into the overnight hours.

Kept things low-end MVFR overnight for now at ksbn, but will need
to watch for ceiling heights just below 1000 feet late tonight
into Thu morning. Otherwise, the broader shield of precipitation
is lifting northward as of 18z, and should impact kfwa no later
than about 19z. A few thunderstorms have already been observed far
to the north and east of the Airport, so have included a mention
in the tafs. With more substantial moisture arriving, expect
conditions will deteriorate to IFR shortly after midnight.
Visibility in the more moderate rain to our south has ranged from
2-4sm, so have kfwa dropping to around 3sm. Scattered shower
activity will be possible later Thu am, and will continue through
Thu afternoon with a gradual improvement in ceilings/visibility.

&&

Marine...
issued at 1150 am EDT Wed may 24 2017

Waves of 3 to 4 feet will approach the shore at a 60 to 90 degree
angle by late this afternoon as they build to around 5 feet. Wave
periods will gradually lengthen to 5 to 6 seconds. These
conditions are supportive of strong rip current development within
sandbars, and strong structural currents near piers and
breakwalls. Furthermore, water temperatures are in the 50's, which
can lead to hypothermia. People visiting the beaches of Lake
Michigan today should stay out of the water. Issued a Small Craft
Advisory and a beach hazards statement for the dangerous
conditions.

&&

Iwx watches/warnings/advisories...
in...beach hazards statement through Thursday morning for inz003.

Michigan...Beach hazards statement through Thursday morning for miz077.

Ohio...none.
Lm...Small Craft Advisory until noon EDT Thursday for lmz043-046.

&&

$$

Synopsis...steinwedel
short term...steinwedel
long term...steinwedel
aviation...mesoscale discussion
marine...mesoscale discussion



Visit US at www.Weather.Gov/iwx

National Weather Service Glossary of Abbreviations