Rising Temperatures Overnight…………..Weekend Outlook Based On Latest DataOctober 12th, 2012 at 2:47 pm by Chad Evans under Chad's WLFI Weather Blog
GOOD MODEL DATA AGREEMENT:
The evening looks dry & cool with mostly clear skies. With an east breeze, temperatures will fall rapidly into the 40s.
Clouds will be on the increase tonight. Temperatures will initially tank to 38-44, but they will then rise from southwest to northeast overnight to 48-54 by 8 a.m. There will be a light east breeze initially, but this will pick up a bit overnight & then turn to the southeast & south by 8 a.m. as warm front approaches & lifts northward.
With this warm front, it does appear a wave of some scattered showers & t’storms will pass late morning-early afternoon. Thing is, coverage will be 40%, so some of you will get poured on with thunder & some of you won’t. For the afternoon-evening the temperature will surge from 72-77 from north to southwest. Wind will be strong to the south to southwest with gusts to 35 mph.
Saturday night looks mostly cloudy to cloudy with brisk to strong south to southwest winds. Temperature will not fall much to only 64-67. The average high temperatures for this time of year are 62-65.
DISAGREEMENT BEGINNING TO ARISE AMONG MODEL DATA:
EARLY SUNDAY MORNING-AFTERNOON:
Models are in increasingly high disagreement regarding timing & evolution of rain/storms (squall line) Saturday night-Sunday morning to afternoon.
What is certain:
Severe squall line will race eastward Saturday after starting out an individual supercells & multi-cells well to our west.
It will windy ahead of & behind front with gusts up to 40 mph at times.
This QLCS squall line will produce damaging winds & some tornadoes with large hail possible before storms gell into a line (when they are first more discrete) well to our west. I would not rule out an EF3 tornado on the triple point from Oklahoma to Kansas to perhaps Iowa. Oklahoma & Kansas look to have a better chance than Iowa of this, per recent analysis.
High pressure to our east, behind our Alberta Clipper, will recycle some dry, more stable air into our area. This will tend to weaken squall line with eastward progression, despite impressive dynamics. HOWEVER, I still believe a few damaging gusts or perhaps a very small, brief EF0 will be possible west of a Medaryville to Lafayette to Crawfordsville line given 80 mph low-level jet & 100 mph upper jet streak overhead.
Now Here’s the Disagreement:
Some data waits to bring squall line in until Sunday LATE MORNING or midday. If this occurs & heating & instability transpire, the severe threat will go up for all or parts of the area. IF this happens, it would be a situation of having a weakening rain/storm band moving in from the west with new, discrete storms with hail, wind, isolated tornado threat popping on the outflow boundary of the band. This also affects when we get clearing on Sunday & whether we see those 70s BEFORE the rain/storms or after.
My Overall Feeling Taking This Into Account:
So, I like keeping the forecast status quo for now, but I cannot ignore some of the models diverging in their outcomes. If data continues to pull towards this more Sunday rain/storm option, then I will change the forecast.