Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 202125
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
325 PM CST Mon Feb 20 2017

.SYNOPSIS...
Issued at 325 PM CST Mon Feb 20 2017

Showers and isolated thunderstorms overspread the upper
Mississippi River valley this afternoon. A strong H85 LLJ with 45
to 50 kts on the VAD will bring in plentiful moisture into the
area. South of the area, temps have raced into the 70s ahead of
the front. The front as it slowly moves east along with the H85
LLJ will drive the main forecast concern for the short term
period.

&&

.SHORT TERM...(This Evening through Tuesday)
ISSUED AT 325 PM CST Mon Feb 20 2017

Main forecast concern for today is whether or not a favorable
thermodynamic environment moves into the area lending itself to
isolated severe thunderstorms. At this time, it does not appear
that the instability will grow large enough for severe weather.
That said, this will need to be watched as shear is more than
sufficient for severe weather.

Have been watching the return of sfc based CAPE across western
Iowa and northern MO along the front this afternoon. This appears
to be the instability that guidance has been hinting at. While
there looks to be instability for thunderstorms, am not sure if
the CAPE is located close enough to the shear to lead to severe
weather. There is a very low chance for severe weather occurring.
As mentioned above, will need to watch this along with any
redevelopment of convection.

The bulk of the precipitation will occur this afternoon and
between 06z Tuesday. Overall most areas will see 0.30 to 0.60
inches of needed precip. Isolated thunder is expected until the
front passes the area. Tomorrow, high pressure moves into the
area. With moisture in place and clearing skies, fog could develop
tomorrow morning. Have added this into the forecast. Otherwise,
tomorrow looks to be another great day across the area with mainly
clear skies and temperature more like late spring than the end of
February.

.LONG TERM...(Tuesday Night through Monday)
ISSUED AT 325 PM CST Mon Feb 20 2017

Record warm temperatures will continue to be the story through mid
week, then the active weather pattern will return more typical
late winter conditions to the area for the weekend.

Tuesday night into Wednesday, a developing low level warm advection
southwesterly flow overnight strengthens during the day ahead of the
next low level cyclone and frontal system moving out of the plains
under a zonal flow aloft. Current consensus timing places the
prefrontal enhanced warm sector over the area during the afternoon.
This would support deep mixing into a dry airmass under full
sunshine, supporting another day of record late February heat. If
mixing reaches up to 850 mb, where temperatures are progged from 10
C to as high as 14 C, then mid to upper 70s would be widespread. The
one change compared to the past several days will be the added soil
moisture from the on-going rainfall, which could buffer these
extreme temperatures some. Thus, for now will maintain highs from
the upper 60s north to mid 70s south, which would be in the range of
5 to 10 degrees above records for the 22nd and possibly pushing all
time February highs at the climate sites, as listed in the climate
section.

Wednesday could also be another day with an enhanced wildfire threat
as afternoon relative humidity values could again bottom out in the
20s and 30s with winds at least in the 10 to 15 mph range. Current
moisture, wind and temperature parameters, which are on the
conservative side considering the setup, drive the grassland fire
danger index into the high range over the entire area, with very
high levels across the southern half of the forecast area. This will
be watched closely over the next couple days.

Thursday through Monday: A strong low pressure system advances over
or just northwest of the forecast area Friday into Friday night with
considerable model differences in timing and track continuing. Ahead
of this system, rain develops along an north of the warm front Thu
into Thu night and high pops are maintained. Elevated instability
still supports at least isolated thunderstorms, especially Thu night
into Friday. If the more progressive, northwesterly tracking models
verify, then Friday`s blended highs from the 40s north to lower 60s
southeast may be too pessimistic and thunderstorms may be more
widespread. Cold air wrap around may bring at least a quick shot of
snow and then brisk northwest winds with highs only in the 30s for
Saturday, which would be sharply colder but closer to climatological
norms for a change. Sunday into Monday should feature a gradual
warming trend with chances for light precipitation.


&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
ISSUED AT 1202 PM CST Mon Feb 20 2017

Tricky aviation forecast for the area as cigs, vsbys and weather
are all factors in the next six hours. A front is forecast to move
through the area bringing showers and isolated thunderstorms.
This could lead to MVFR to IFR conditions at the TAF sites. Later
this evening, clouds are expected to clear and cooling could lead
to low level stratus and vsbys across the area. Guidance suggests
IFR at most sites, however with confidence in this occurring
decided to hedge that way with MVFR cigs and vsbys tomorrow
morning.


&&

.CLIMATE...
ISSUED AT 325 PM CST Mon Feb 20 2017

Record Highs for today February 20th...

Moline.........65 in 1930
Cedar Rapids...60 in 1981
Dubuque........61 in 1981
Burlington.....67 in 1983

Record Highs for February 21st...

Moline.........66 in 1930
Cedar Rapids...68 in 1930
Dubuque........63 in 1930
Burlington.....68 in 1983

Record highs for February 22nd...

Burlington.......66 in 2000 (and previous)
Cedar Rapids.....64 in 1984
Dubuque..........61 in 1984
Moline...........66 in 1922


Record highs for the month of February...

Burlington.......76 on the 24th in 1930
Cedar Rapids.....73 on the 15th in 1921
Dubuque..........67 on the 12th in 1882
Moline...........74 on the 19th in 2017*

*Previous record was 73, on the 15th in 1921, tied on the 17th in
2017

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...Gibbs
SHORT TERM...Gibbs
LONG TERM...Sheets
AVIATION...Gibbs
CLIMATE...Sheets


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