IEM Daily Bulletin

[Iowa Mesonet]

Iowa Environmental Mesonet Daily Bulletin
Data valid for 03 April 2008

> News
    No news is good news

> Yesterday's Daily Feature

 +----------------------------------------------
http://mesonet.agron.iastate.edu/onsite/features/cat.php?day=2008-04-03
 | Title : Snow possible today?
 | Date  : 03 Apr 07:28 AM
 | Votes : Good: 33   Bad: 10
 +----------------------------------------------

The featured graphic is of forecasted temperature, dew point, and precipitation for Thursday afternoon.  The red arrow is the wind direction.  This plot nicely illustrates a process called "evaporative cooling".  The wind is bringing drier air from the east underneath precipitation, which is associated with close to saturated air.  As the water drops fall thru this drier layer near the surface, it evaporates, which cools the air.  The effect of this process can be seen with the coolest temperatures found in Western Iowa while warmer air surrounds.  The big question is if this process can cool the air enough to produce snow!  The heavier rain showers will have the best chance of producing snow, since evaporative cooling will be strongest with those storms.

> NWS Watch/Warning Summary
*** Products issued on 03 Apr 2008

             Summary +_________ By WFO ____________+  Watches 
Type         US   IA | ARX   DVN   DMX   OAX   FSD |  US 
Tornado      12    0 |   0     0     0     0     0 |   4
Svr Tstorm  118    0 |   0     0     0     0     0 |   3
Fl Flood      0    0 |   0     0     0     0     0 | N/A

ARX = LaCrosse, WI  DVN = Davenport, IA    DMX = Des Moines, IA 
OAX = Omaha, NE     FSD = Sioux Falls, SD