Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service northern Indiana
159 am EDT Tuesday may 5 2015

issued at 152 am EDT Tuesday may 5 2015

A front will meander across the area through today...and be
accompanied by occasional showers and isolated to scattered
thunderstorms. Cloud cover and rainfall will keep temperatures in
the 60s across far Southern Lower Michigan to the middle 70s into
west central Indiana. Lows tonight will fall back into the 50s.


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 06z tafs through 06z Tuesday night)
issued at 144 am EDT Tuesday may 5 2015

Favorable downstream convective maintainence parameters suggest
eastern Iowa/northwestern MO/northwestern Illinois convective complex to maintain
sufficiently for inclusion of tempo thunderstorms and rain later this am across northern
in. Thereafter...abundance of trailing stratiform rafl to likely
persist and saturate low levels amid cool/backed flow low level
regime for ceilings to lower. Kept kfwa at or above fueling/alternate level
criteria for now as shallow srly afternoon flow to provide some
subcloud drying..though dependent upon where meandering surface
boundary lies out in wake of am convection.


Iwx watches/warnings/advisories...


short term...logsdon
long term...T

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

Follow US on facebook...twitter...and youtube at:

National Weather Service Glossary of Abbreviations