898 
FXUS63 KDMX 040212
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
812 PM CST Tue Mar 3 2020

...Updated for Near Term Weather Trends...

.UPDATE...
Issued at 812 PM CST Tue Mar 3 2020

Trends this evening have pointed to the wintry precipitation being
a bit farther south than previously thought by about a county or 
two. This shift can be seen in the arriving 00z NAM as well as 
recent runs of the HRRR and RAP. There is also some disparity in
the amount of QPF and resulting snow. Generally, guidance is 
pointing towards around an inch or so of snow accumulations.
However, the NAM and the 1z NBM v3.2 shows a narrow strip of 
higher totals from around Emmetsburg to Waverly. While the BUFKIT
NAM data has not arrived yet, the NAM has had a very cold 
boundary layer this winter. Therefore, it is possible that it has
a colder than reality surface temperature now and in the near
future allowing for its higher snow totals. Further, Iowa DOT 
road temperatures are still above freezing in the low 40s across 
northern Iowa early this evening. If there were to be a narrow 
band of higher snowfall, it would likely be east of I-35 where 
the precipitation will fall with temperatures and road 
temperatures that would support more accumulation. Will continue 
to monitor environment and make adjustments as needed through the 
evening and overnight.

&&

.SHORT TERM.../Tonight through Wednesday/
Issued at 312 PM CST Tue Mar 3 2020

Confidence: Medium Tonight and High Wednesday

Main concern will be impacts from system tonight.  Fast moving and 
compact PV anomaly dropping southeast into Iowa overnight. This will 
induce a weak surface low and associated H850 feature which are 
forecast to track across central Iowa, with the Euro placing the sfc 
low a bit farther south into southern Iowa. The low will track along 
a cool front dropping south as well. Most of the 12z synoptic models 
have backed off on qpf amounts with the hires models continuing to 
suggest a band of higher qpf just north of the low and mainly over 
northern Iowa. The better forcing arrives over our northwest 
forecast area around 03z and quickly tracks east and generally 
existing the east between 09-12z. Currently temperatures are in the 
lower to mid 40s over the north with mid 50s in the south.  Road 
temperatures are in the mid 60s over much of the region this 
afternoon.  Farther north, daytime temperatures remain in the mid 
30s as far north as southern North Dakota.  Tonight the area will 
first need to overcome the drier airmass and also today's warmth in 
the lower layers/roads prior to any real impacts tonight. With the 
potential for up to .20 inches of qpf, even with a changeover across 
the north, snowfall amounts continue to lean toward lighter amounts 
of around 1 inch with locally slightly higher totals. Generally it 
appears to be a battle between the arrival of the surface cooler air 
and the precipitation crossing the area though temperatures aloft
will be cool enough to start off as snow. Tonight's lows will 
drop to the mid to upper 20s north while the south drops into the 
lower to mid 30s. The system will quickly depart Wednesday morning
with a return of some sunshine as well as milder temperatures 
again over the south during the afternoon. High pressure will 
quickly slide east in the afternoon with a return of southwest 
flow by late day.

.LONG TERM.../Wednesday night through Tuesday/
Issued at 312 PM CST Tue Mar 3 2020

Confidence: Medium to High 

Other than wind, the bulk of the forecast will be quiet for the next 
few days. Another storm will track along the US Canadian border late 
Wendesday night into Thursday with a trailing front and stronger 
mixing moving across our area. There remains a weak signal for some 
light precipitation over northern Iowa or southern Minnesota during 
from Thursday morning through Friday morning but confidence is 
currently low regarding occurrence. Winds Thursday afternoon will 
again be brisk with models suggesting that gusts may reach 40 to 45 
mph during the late morning and afternoon hours. Will need to monitor 
for potential headlines. As well, colder temperatures should filter 
across the region by afternoon; especially north where highs are 
more likely to be near the 40 degree mark while the south will still 
see some lower to mid 50s.  The drier airmass, stronger winds and 
mild temperatures over the southwest Thursday could result in an 
elevated grass fire situation, but will need to evaluate moving 
forward. The remainder of the extended will see a rapid warm up over 
the weekend with H850 temperatures reaching 8C by 00z Sunday and as 
warm as 9 to 10C by 00z Monday. This should propel highs into the 
60s by afternoon.  Both the GFS and Euro are in decent agreement for 
Monday into Tuesday with a well developed trough tracking east 
across the region late Sunday night/Monday followed by high pressure 
on Tuesday. Showers are likely into Monday then clearing later in 
the day.  Highs will cool Monday into Tuesday back into the 50s then 
40s. 

&&

.AVIATION.../For the 00Z TAFS through 00Z Wednesday evening/
Issued at 542 PM CST Tue Mar 3 2020

Winds will decrease this afternoon as clouds spread over the area
with a quick shot of wintry precipitation expected overnight,
mainly over the northern half of Iowa. This wintry precipitation
will arrive later this evening bringing MVFR and perhaps IFR at
times to FOD/MCW/ALO. Farther south, there could be a brief shower
at DSM. Conditions will have improved back into VFR by daybreak
Wednesday with light winds from the northwest becoming from the
southwest later in the day.


&&

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

$$

UPDATE...Ansorge
SHORT TERM...REV
LONG TERM...REV
AVIATION...Ansorge