ONE STORM DOWN, MORE ON THE WAY...

February 21, 2018

The past few days we've been focused on the weather system that's brought heavy precipitation to much of the central Midwest. One of the things I posted on several days ago was the huge amounts of water vapor that would be available for precipitation. We measure that in PWATS (precipitable water vapor). This came out of the NWS office in the Quad Cities today. The water vapor on a morning sounding was 360% of normal, an all-time record for the date.

Sure enough, some very impressive rainfall totals were measured. Through Tuesday morning 24 hour estimated totals came in like this around my area. Lots of places with 1-2" amounts. 3" was reported in Macomb, Illinois. 

In Moline, Illinois (Quad Cities) 1.36" fell in a 24 hour period, breaking the record for the date of 1.33" set in 1953.

The heavy rain and frozen ground has resulted in a rapid rise on the Rock River. At last report major flooding was expected with a crest in Moline, Illinois of 14.4 feet February 23rd. Sunday the stage was about 9.5 feet. Up up and away.

 

Advisories and warnings for flooding are out for a large part of the central U.S. late Tuesday.

 

You can also see the set-up that's brought the heavy precipitation. A nearly stationary boundary running from Chicago to Dallas is dividing temperatures in the 70s from readings below zero. That's generating the lift to squeeze out that water vapor and bring on the rain.

Record highs were established in many parts of the east. A bunch of cities had their all-time warmest February highs. Pittsburgh hit 78!

 Just as impressive as the temperatures are the dew points. They go from 18 below in Montana to 72 in Texas. Now that's a dry line!

After a dry and colder day Wednesday the pattern reloads again with a couple more disturbances...one Thursday, the other Friday night Saturday. The Thursday system is minor and won't bring much more than a light mix to my area. The weekend storm is much more substantial. The last 2 runs of the GFS show a deep low intensifying on a track through central Iowa.

If this holds, the heavy snow bypasses my area but chances increase for more rain and possible thunderstorms. Temperatures should also spike one more time towards the 50s southeast of the low pressure track. There's even a chance of severe storms from SE Iowa into WC Illinois and eastern Missouri. Anyway, the GFS shows more significant rain by February standards.

It also dumps a bunch of snow on the upper Midwest.

The EURO has been far less bullish on such deep intensity and until I see it on the bandwagon I would be cautious of what the GFS is selling. It's not unrealistic but until I get consistency I consider this a low confidence forecast period. Something will come of this energy but the details are still in question. Roll weather...TS

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© 2019 Terry Swails