Scientific Forecaster Discussion

NWS Discussion
			
				

Area forecast discussion 
National Weather Service Des Moines Iowa 
310 PM CDT Thursday may 23 2013 


Short term.../tonight /... 
issued at 310 PM CDT Thursday may 23 2013 


Little of concern tonight with Iowa between High Plains ridge and 
departing Great Lakes trough. Although skies will be clear with 
light winds as surface high pressure crosses the upper MS 
valley...overnight lows should only dip into the upper 30s northeast 
keeping frost concerns at Bay. 


Long term.../Friday through Thursday/... 
issued at 310 PM CDT Thursday may 23 2013 


Active period setting up for the Holiday weekend into next 
week...with main issued surrounding chances for thunderstorms and 
potential for heavy rain. High pressure initially over the area 
Friday with dry conditions expected...however the surface high quickly 
shoves east with warm air advection and moisture advection back into western Iowa 
by late Friday afternoon. This will allow for some potential 
thunderstorms across western Iowa late in the afternoon. Chances for 
thunderstorms to become more widespread across the County Warning Area as weak 
shortwaves push eastward through the upper level ridge expected to 
remain in place through the weekend. Thunderstorm chances will 
remain with the climatological favored times in this type of 
pattern...mainly in the evening to overnight hours and lingering 
into the morning. With the extended chances for thunderstorms and 
rainfall...flash flooding and river flooding becomes a concern. 
Moisture transport oriented into Iowa for much of the Holiday 
weekend...precipitable waters  well above average increasing into the 1.3 to 1.5 
inch range...and fz level quite high suggesting efficient rain 
production through the weekend. Widespread rainfall amounts of 1 
to 2 inches with locally higher amounts are possible through the 
Holiday weekend. Severe parameters not that great...so widespread 
severe weather is not anticipated. 


Upper level ridge begins to shift east slightly and dampen 
some...with a surface warm front expected to lift northward through the 
state Tuesday. An upper level closed low digs into the Desert 
Southwest with impulses ejecting out ahead of the main system 
through the region. With the warm front stalling out across the County Warning Area 
Tuesday into Wednesday...and the energy lifting through the 
area...thunderstorm chances continue into next week across the area. 
Warmer temperatures also expected with the warm front lifting 
north...with much of the area returning to 70s and 80s by the middle 
of next week. 


&& 


Aviation...23/18z 
issued at 1220 PM CDT Thursday may 23 2013 


MVFR stratus roughly along rdk-csq-i75-pea-iow line at 1730z will 
continue to drift south at around 20 kts...exiting kotm by 19z. 
This will lead to clearing skies into the evening which will 
persist until scattered middle/high clouds increase late Friday morning. 
Expect minor gusts today to diminish toward sunset with light 
winds gradually veering to southeasterly by early Friday. 




&& 


Dmx watches/warnings/advisories...none. 


&& 


$$ 


Short term...small 
long term...beerends 
aviation...small