TUESDAY: Sunny and breezy at times. High: 47. Winds: Southwest 10-15 mph, gusting to 25 mph.
TUESDAY NIGHT: Mostly cloudy with a few flurries after Midnight. Low: 31. Winds: Southwest 5-10 mph.
WEDNESDAY: Cloudy and chilly with a few flurries. High: 41. Winds: West 10-15 mph.
Storm Team Meteorologist
NOVEMBER 9, 2015
NORMAL HIGH: 56
NORMAL LOW: 37
RECORD LOW: 9 (1991)
SUNRISE: 6:36 a.m.
SUNSET: 4:48 p.m.
SEVERE WEATHER THREATENS ILLINOIS WEDNESDAY - INCLUDES THE POSSIBILITY OF TORNADOES.
SPRINGFIELD (WICS) - Quiet and tranquil weather continues for central Illinois today. Highs, seasonal, in the mid to upper 50s. Lows have been chilly the past couple of nights dropping into the upper 20s for Springfield. A minor upper level disturbance just off to our east spread for showers and sprinkles northward into Indiana, but so far everything remained east of the state boarder, so we were largely left alone with wall-to-wall sunshine.
Temperatures start to climb into Tuesday and Wednesday with return flow, aka. southerly winds. Light at first, but strong on Wednesday. Winds Wednesday afternoon will be about 20-25 mph with wind gusts up to 40mph. That before a strong cold front give us our severe weather chance. Before we talk severe weather, winds increase even further for a couple hours into Wednesday night on the backside of this cold front, gusting close to 50 mph! Temperatures will reach the mid 60s and humidity (dew point) will be approaching 60°.
The set up for Wednesday; a low pressure currently off the coast of California quickly spins and strengthens into the central plains Tuesday and out towards Iowa on Wednesday. Between Tuesday night and Wednesday night will be when the majority of the strengthening, or "deepening" takes places. This alone provides a lot of lift and forcing in the atmosphere, especially at the low levels of the atmosphere. Plus a strong cold front increasing the amount of low level forcing even further. But the big factor for our severe weather forecast will come from the upper levels, ie. the jet stream. The orientation of the jet stream, negative tilt, adds a great amount of shear in the atmosphere. This shear will easily create supercell thunderstorms. These will be able to produce all types of severe weather, including tornadoes. The one limiting factor for Wednesday, the instability, or energy. It's fairly weak, especially as severe weather is concerned. But the forcing and dynamic support is so great, we think even a little or modest instability will have an amplified result.
As for the result, the primary concern will be the threat of widespread damaging winds. There's so much wind energy associated with this system, thunderstorms could easily produce significant wind gusts up to 70 mph in Illinois (perhaps 80 mph in the central plains). Tornadoes are a concern too, but we're walking a fine line and expect a narrow corridor of best tornadoes possibilities/probabilities. This corridor is a balance between max shear, closest to central of low pressure to the north, and available moisture and instability, where more is available to the south. Our forecast: between Omaha, NE Tuesday night and into northern Missouri for Wednesday afternoon as well as western and central Illinois into the early evening. Timing for storms in central Illinois is set for 5pm to 9pm.
Behind the front and the storms, winds pick up at first, again up to 50 mph. Temperatures drop considerably, into the 50s on Thursday, upper 40s Friday while still staying breezy or windy. Lows look to approach the upper 20s Friday night before stabilizing this upcoming weekend.
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THE 7-DAY TEMPERATURE OUTLOOK: Look for highs in the low 60s Tuesday; mid 60s Wednesday; mid 50s Thursday; upper 40s Friday; mid 50s Saturday; around 60 Sunday; and, mid 50s Monday. Overnight lows will fall to the low 30s Monday night; mid 40s Tuesday and Wednesday night; mid 30s Thursday night; upper 20s Friday night; mid 30s Saturday night; and upper 30s Sunday night.
Thomas Patrick - Storm Team Meteorologist