Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service northern Indiana
647 PM EDT Monday may 4 2015

Synopsis...
issued at 1149 am EDT Monday may 4 2015

A front will undulate across the area through Tuesday...and be
accompanied by showers and thunderstorms. After that...temperatures
will warm much above normal during the second half of the week
with highs reaching the 80s.

&&

Update...
issued at 646 PM EDT Monday may 4 2015

Lowered probability of precipitation and dropped thunder mention (except for far southern
zones) through the early morning hours with weakening multicell
clusters to remain focused just south-southwest of the local area along
leftover composite outflow/instability gradient. Only minor
changes otherwise with better rain/thunder chances still on track
for later tonight/Tuesday am with mesoscale convective system/mesoscale convective vortex remnants.

&&

Short term...(this evening through tuesday)
issued at 239 PM EDT Monday may 4 2015

Kiwx radar and latest surface analysis indicating remnants of
showers has exited the area as frontal boundary now sinking down
into northern County Warning Area. 17z mesoanalysis indicating sbcapes have
rebounded to 1500j/kg across central Illinois suggesting we still
may see some airmass recovery in the south by late afternoon/early
evening so will keep chance probability of precipitation going there. Main focus will be for
convective redevelopment out west in the presence of better
dynamics. Water vapor imagery showing short wave energy moving up
along the backside of upper ridge and will coincide with axis of
thetae ridge and effective shear values around 50kt. Hires guidance
indicating this will evolve into nocturnal mesoscale convective system and propagate
eastward along stalled frontal boundary tonight. Based on this
scenario will keep window of likely probability of precipitation going after 06z in
anticipation of mesoscale convective system arrival. Frontal boundary then lifts back
northward on Tuesday and will focus best chances for precipitation in the
northern half of the County Warning Area...but all hinges on how overnight
convection evolves so will keep everything in chance range for now.
Expect temperatures in 55-60 range for lows tonight while frontal boundary
is expected to produce strong gradient across the forecast area on
Tuesday with upper 70s in the far south to middle 60s in the north.

&&

Long term...(tuesday night through monday)
issued at 239 PM EDT Monday may 4 2015

Stout middle level ridge development expected downstream of western US troughing this
period west/much above normal temperatures and generally dry until lt period.

Much slwr 12z model consensus of northeastward ejection of Four Corners
impulse lt next weekend looks ideal especially in light of follow separation
across the western US and common model biases. Thus downplayed probability of precipitation Friday
afternoon through sun in reflection of general poor synoptic sprt here
and lackluster moistening eastward of the MS river. At some point no doubt
upstream conv evolution and/or piecemeal ejection of western energy will
augment much higher mesoscale forcing at times however based on gross
spectral solution scope...that does not seem plausible until Friday
night at the earliest and most likely lt Sat and again on sun.

&&

Aviation...(for the 00z tafs through 00z Tuesday evening)
issued at 646 PM EDT Monday may 4 2015

Mainly dry/VFR conditions are expected through the early morning
hours as convection remains focused south of the area along
leftover composite outflow across central in/IL. Convectively
enhanced shortwave will likely bring widespread showers/embedded
thunder and flight restrictions back into the region later tonight
into Tuesday morning as it interacts with primary frontal boundary
draped across northern IL/in.

&&

Iwx watches/warnings/advisories...
in...none.
Michigan...none.
Ohio...none.
Lm...none.
&&

$$

Update...steinwedel
synopsis...skipper
short term...logsdon
long term...T
aviation...steinwedel



Visit US at www.Weather.Gov/iwx (all lower case)

Follow US on facebook...twitter...and youtube at:
www.Facebook.Com/nwsnorthernindiana
www.Twitter.Com/nwsiwx
www.Youtube.Com/nwsnorthernindiana

National Weather Service Glossary of Abbreviations