Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 221755
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1255 PM CDT Wed Mar 22 2017

.SHORT TERM.../Today through Tonight/
Issued at 341 AM CDT Wed Mar 22 2017

Warm air/theta-e advection moves across Western/Northern Iowa
today along with a quick shot of forcing this morning. This may
bring a quick shot of light precip across these areas this
morning. The caveat is that there is quite a bit of dry air in the
lower layers to contend with and the likelihood is that much of
the precip will evaporate aloft producing virga. If we do get some
precip however, the precip will start out as snow early this a.m.
then mix with rain as we get towards mid morning before lifting
Northeast by late morning.

Tonight an upper ridge moves overhead so expecting mainly dry
conditions tonight. Temps will not be as cold as we have seen
tonight as we get into another round of weak warm advection.

.LONG TERM.../Thursday through Tuesday/
Issued at 341 AM CDT Wed Mar 22 2017

On Thursday the upper ridge moves East as a deep trough digs into
the West. A surface low develops with a frontal boundary extending
into West central to Northeast Iowa by Thursday evening. Initially
surface temps will be near/below freezing across the North and
with the warm air aloft and some weak theta-e advection and
forcing, some light freezing rain would be possible mainly
Northeast. A second stronger shot of theta-e advection moves
through in the afternoon. Showers and perhaps some thunderstorms
are possible Thursday late morning and afternoon associated with
this second surge of theta-e advection and frontogenetical
forcing. Precip should be ongoing into Thursday evening but I do
expect a break in the precip across Southern into central Iowa.

Friday through Friday night an upper low develops from the trough
and becomes stacked with the surface low. This will slow the
progression of the system as it treks Eastward and will allow for
decent moisture, instability and some forcing to work into Iowa.
We should see some prolonged precip and some thunderstorms Friday
and Friday evening.

On Saturday we will be caught in deformation zone precip and while
thunderstorm chances diminish, it will be a wet day with moderate
rainfall at times. It looks to me as though we may even see this
precip linger into Sunday morning before finally shifting East out
of the state.

For the rest of the long term...the weather will remain unsettled
as numerous fairly strong shortwaves move from West to East across
the U.S. At this time however it appears that these systems will
move across the Southern U.S. and mainly graze Southern Iowa. On
Monday a Northern stream wave seems to phase with the Southern
stream system and bring us at least a slight chance of precip.

Temp-wise, Friday will be the warmest day in the forecast period
but temps will be quite mild through the period with highs in the
40`s and 50`s.

&&

.AVIATION.../For the 18Z TAFS through 18Z Thursday afternoon/
Issued at 1255 PM CDT Wed Mar 22 2017

Mid/high clouds to move in this afternoon and remain in place
through tonight. CIGS to lower to MVFR possibly IFR as moisture
pushes northward tonight. Winds to shift to mainly southeasterly
through the period. Some showers will move in Thursday morning, so
highlighted with a VCSH for the moment as coverage is uncertain.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...FAB
LONG TERM...FAB
AVIATION...Beerends



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