Area Forecast Discussion
Issued by NWS Des Moines, IA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
FXUS63 KDMX 130944

Area Forecast Discussion
National Weather Service Des Moines IA
344 AM CST Mon Feb 13 2017

.SHORT TERM.../Today through Tonight/
Issued at 339 AM CST Mon Feb 13 2017

Short term weather will be relatively benign with system across the
southwest remaining well south of the state through tonight.
Meanwhile, warm advection is forecast to persist through today with
thermal ridging building toward the state by late in the day.  Some
high clouds will pass across southern Iowa during the day, but most
locations will see plenty of sunshine as the airmass remains dry.
Overall, its a good setup for a decent warmup today given the warm
advection, decent southwest winds and mixing and good insolation. In
addition, snow cover in the forecast area is limited to around Mason
City and Northwood with most locations snow free at this point.
Therefore, have remained on the high end of guidance for today with
low to mid 50s from Highway 30 on south to mid 40s over the snow
areas in the far northeast.

Winds will gradually shift to the northwest tonight as a trof axis
passes through the state, but the bigger push of colder air doesn`t
arrive until later Tuesday.  Therefore, overnight lows will remain
above normal, helped by the northwest winds which will promote at
least some minor near surface mixing through the night.  With the
dry atmosphere remaining in place, there is no threat of
precipitation through tonight.

.LONG TERM.../Tuesday through Sunday/
Issued at 339 AM CST Mon Feb 13 2017

Continuing with dry and well-above normal to possibly record warm
temperatures for this long-term fcst period.

No Hazardous WX Impacts Expected
Confidence: High

Tuesday through Thursday...
00z Mon wv imagery shows a shortwave coming off the Rockies and
propagating southeastward through Alberta. This low is slated to
pass ride along the Great Lakes and into the NE CONUS. An
attendant cold front will push through Iowa during the day
Tuesday. Now that the low is off the Rockies, it`s resolution has
been improved. The magnitude of cold air seems to have lessen
with the 00z Mon model suite. 850mb temps seem to be similar to
where they were yesterday...perhaps a few degrees warmer. With the
fropa not expected until the afternoon, stronger CAA will be
delayed and thus would expect temps similar to
yesterday...slightly cooler with more cloud cover possible. CAA
will last into Wednesday afternoon as a thermal ridge building
over the intermountain west nears Iowa.

Friday and beyond...
Models remain generally unchanged in building this thermal ridge
well into Canada and begin crashing it down over Iowa Friday. In
the 00z Mon suite, 850 mb temps have increased a few degrees
versus previous runs...with a pocket of temps in the +10C to +15C
range. Have continued with raising temperatures near 5 degrees
above SuperBlend guidance to match or slightly exceed temperatures
from previous forecast. This still may not be warm enough, so
will possibly push temps into upper 60s to 70s in subsequent
updates if this setup continues to hold.

The GFS and ECMWF continue to hint at a shortwave and attendant
trough axis/boundary possibly passing through the upper Midwest on
Saturday. The run-to-run consistency on handling this feature is
terrible at this time, so have nudged temperatures closer to
Friday`s values to introduce persistence until proven otherwise.

As of now, here are some Des Moines record temperatures that may
be in jeopardy of being neared and/or broken...
Fri 2/17: High Max 68 (2011)
Sat 2/18: High Min 42 (1981)
Sun 2/19: High Min 44 (1930)
Mon 2/20: High Min 51 (1930)
Mon 2/20: High Max 64 (1981)


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 339 AM CST Mon Feb 13 2017

Little has changed since 00z. VFR conditions and clear skies are
in place across Iowa at 06z and this should continue into the
early morning. There is high confidence VFR will persist through
the entire period with nothing more than patchy mid/high
cloudiness into Monday and mainly south. Winds will remain light
overnight and then gradually become SW and increase after 17z
before decoupling again into the evening.





LONG TERM...Kotenberg
AVIATION...SMALL is the U.S. government's official web portal to all federal, state and local government web resources and services.