Notes: A time lapse of the thunderstorm that moved through NIU
as seen from Davis Hall yesterday evening, right here:

http://vimeo.com/42246854

FORECAST FOR DEKALB AND VICINITY, 5/16/12, 11:55 AM

Today...mostly sunny and cooler.
High of 70 degrees. Northeast winds
10-20 MPH.

Tonight...clear and chilly. Low of 45
degrees. Southeast winds under 5 MPH.

Tomorrow...mostly sunny to sunny.
High of 73 degrees. Southeast winds
10-20 MPH.

Extended outlook...Friday through Tuesday...

Friday...partly cloudy. Low in the lower 50s.
High around 80.

Saturday...partly cloudy and warm. Low
in the upper 50s. High in the middle 80s.

Sunday, the partial solar eclipse at and
before sundown...variable cloudiness with
a good chance of thunderstorms. Low around
60. High around 80.

Monday... decreasing cloudiness. Low in the
upper 50s. High in the lower or middle 70s.

Tuesday...sunny. Low around 50. High in the
middle or upper 70s.

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CLIMATE DATA: Yesterday's high, 86 degrees; last night's low, 47 degrees.
The average high/low temperature is 69/47. We have had no rainfall
equivalent at the DeKalb campus over the last 24 hours ending at 7 AM
this morning. Forecast was for 84/49 with .05" to .33" of rain with 50% 
coverage; this verified.

We have had 1.18" of rainfall equivalent this month. On average,
we should see 4.55" of rainfall equivalent by May 31. We have had
8.53" of rainfall equivalent so far this year. By May 31, our
average annual liquid total should be 13.09".
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SEVERE/HAZARDOUS WEATHER OUTLOOK: There is a good chance of thunderstorms 
around Sunday. These have marginal to modest potential for them to become 
severe, with high winds and some hail the main threats. We'll have more
details as we get closer to the weekend.

Otherwise, no severe weather is expected though Saturday.
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PRECIPITATION: Nothing through Saturday.
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FORECAST DISCUSSION: Everything is going fine with the forecast.
The rain arrived an hour later than expected last night, and no severe
weather was reported, even with a few severe thunderstorm warnings off to
our east. High pressure over us today moves east of the area tomorrow,
bringing southerly winds and temperatures rebounding from around 70 today
to the 80s over the weekend. The next cold front seems to want to come
through Sunday evening, as the models all locked onto that solution this
morning. This is reasonable, so I went with decreasing clouds on Monday,
yanking the rain. Should this slow down some, I might have to change
that...but confidence is improving that Monday will be dry. After that,
it's clear sailing until Wednesday or Thursday of next week, with the next
weak cold front wanna-be. It looks like if there's going to be any severe
weather over the next 10 days, it should be Sunday afternoon or evening.
Otherwise, weather nil.

On the surface map this morning...a low over northern Quebec had a cold 
front southward to central New York state, then southwest across far 
southern Illinois, to central Oklahoma, to eastern Colorado. From there, 
it becomes a warm front as it heads northward and meets with another low
over southern Saskatchewan. This system produced strong and isolated 
severe thunderstorms from Michigan into north central Illinois yesterday
at and just after the dinner hour. Strong to severe thunderstorms are 
likely ahead of the front in the northeastern U.S., where stronger wind 
shear and some moisture will produce thunderstorms with damaging winds and 
some hail. A severe thunderstorm watch is already out from central and 
eastern New York eastward through western Maine through the afternoon 
hours.

A trough of low pressure from New York to North Carolina to eastern 
Florida is the remnant of a cold front. This system will produce scattered 
showers and thunderstorms along and near it later this afternoon.

The low in Saskatchewan has a trough of low pressure southwest to southern 
Oregon...and a second cold front is crossing the U.S./Canadian border 
along the British Columbia and Alberta boundary. These features, and heat 
with some humidity, will kick off scattered showers and thunderstorms in 
the northern and central Rockies today.

High pressure over Minnesota dominated the Great Lakes and northern Plains 
with sunny weather and seasonable temperatures, while summer heat was 
building in the southwestern U.S. Phoenix should be over 100 degrees 
again. 

Our forecast problems...the cold front coming through on Sunday evening
or so.

Today through Saturday...as the high near Duluth, MN at noon pushes 
eastward over the next several days, winds should start coming from a 
southerly component starting this evening, and then get gusty on Friday 
and Saturday. This will help bring back the warm air we saw yesterday into 
our area on Friday and Saturday...with the warmup starting later tomorrow 
afternoon. All of this with few clouds until later on Friday and Saturday, 
as Gulf moisture finally starts to come northward into our area towards 
the weekend, bringing some clouds with it...but no rain. After a high 
today around 70, and in the lower or middle 70s tomorrow...south winds 
behind the warm front on Friday should push us to 80, if not warmer...and 
middle 80s on Saturday. Look for lows to warm from the middle 40s tonight, 
to the upper 50s by Saturday morning as the heat and some humidity finally 
return to our NIU campuses.

Next week...as mentioned, the next cold front now in Canada should get 
here on Sunday. It will be similar to last night, except that we may have 
a little Gulf moisture with it...IE, the base of the storms won't be at 
10,000'! However, wind shear looks paltry, even though instability may be 
somewhat OK. So, it looks like a summertime frontal passage with an hour 
or two of noisy thunderstorms, and then...that's it. So, I boosted 
temperatures back up to 80 degrees, and if we get enough sun, we could be 
several degrees warmer than that. Uncertainty is high, though, so I kept 
the temperatures at around 80 for now. After that...the models have just 
backed off on the rain for Wednesday/Thursday...with nothing until next 
Saturday. Thus, after a brief cool down to highs in the 70s in the first 
part of next week (gorgeous weather!), by next Friday or Saturday, we 
could very well hit or get close to 90 degrees, with higher humidity.

So...unusually quiet are the highlights of this forecast period. Outside 
of a thunderstorm Sunday evening...the next 10 days may be dry. So, look 
for near average temperatures through tomorrow, then above average through 
much of next week. Rainfall should be below to much below average. Sunday 
looks like a quarter inch at best, barely better than what we saw
last night. In other words, generally dry until further notice.

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Gilbert Sebenste                                                     ********
(My opinions only!)                                                  ******
Staff Meteorologist, Northern Illinois University                      ****
E-mail: sebenste@weather.admin.niu.edu                                  ***
web: http://weather.admin.niu.edu                                      **
Twitter: http://www.twitter.com/NIU_Weather                            **
Facebook: http://www.facebook.com/niu.weather                           *
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