Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 201152

Area Forecast Discussion
National Weather Service Quad Cities IA IL
552 AM CST Mon Feb 20 2017


Issued at 330 AM CST Mon Feb 20 2017

The latest sfc analysis was indicating increasing warm push/type of
warm front bi-secting IA from NW-to-SE, with increasing llvl
southeasterly pressure gradient around it. SFC pressure falls were
increasing up the MO RVR valley ahead of northward advancing
conveyor of showers and thunderstorms acrs the east central Plains.
Aloft, upstream elongated trof acrs the Western plains trying to
push east and buck the sharpening upper ridge edging eastward into
the western GRT LKS ATTM. Vertical profilers off the RADAR
network showing southerly 40-45 KT LLJ up the MS RVR Valley, while
cloud cover and southeasterly SFC winds keeping local ambient temps
up in the 40s and mainly 50s acrs the CWA.


.SHORT TERM...(Today and Tonight)
ISSUED AT 330 AM CST Mon Feb 20 2017

Today...First concern of the morning will be watching the central IL
fog pool and if llvl southeasterly flow can slosh this bank toward
the southeastern and eastern CWA this morning. Those areas cooler
in the low to mid 40s or saturated at their respective sfc DPTS/TWs
and not confident the fog bank can make it northwestward into a
warmer llvl environment with increasing mixing, but will keep at
least patchy to areas of fog in these areas through mid morning and
watch trends toward sunrise. Otherwise near term models and upstream
trends suggest a slowing of the incoming band of showers and
embedded thunderstorms acrs the local area. May just see a few banded
wings of sctrd showers and some thunder skirting north acrs the
western CWA this morning and into the afternoon, with showers and
thunder not becoming more widespread west of the MS RVR until after
20z or so. Much of the eastern CWA may stay dry until late afternoon
or evening. So with precip delay and mild temp "jump-start" to the
day, will again adjust/trend temps up from current advertised
values...record highs at all climate sites. Despite the cloud cover
(initially high level anyway) and increasing SFC DPTS, unseasonably
mild thicknesses and better mixing today will again support a strip
of upper 60 to low 70 high temps generally along and east of the MS
RVR or the southeastern half to third of the area last to get in on
the precip. Only problem in the far east and southeast areas if
indeed the low stratus/fog bank makes it into those areas limiting
warm up potentail this morning.

Tonight...Highest POPS warranted sweeping from west-to-east from
late afternoon and through 10 PM to 11 PM or so. Again bands of
showers with some embedded thunder. Shear profiles are strong this
evening with bulk values ranging from 45 up to 60 KTS, and some
signs low level based CAPES of 100-300 J/KG moving along the main
band of convection. Vertical saturation profiles are not that
conducive though to severe storms, but with the other parameters can
not totally rule out an isolated low CAPE-high shear occurrence of
some type. Bulk of the near term and HIRes solutions walk out most
of the showers eastward out of the eastern CWA by 08z to 10z Tue
morning. Taking into account unseasonable PWAT feed of 1.3 to 1.5
inches and extent of forcing/shear wringing out the precip, will
advertise widespread rainfall amounts of 0.30 to 0.60 tenths of an
inch by the time the showers move out. Also localized swaths that
can get repeated storm clusters moving along could get up to an
inch of rainfall. Thawed out ground to absorb, and don`t see much of
a nuisance flood threat. But some urban ponding of water possible.
Late cool advection push behind frontal passage to produce lows in
the low to mid 40s west of the MS RVR by 12z Tue, but held up in the
mid to upper 40s or even around 50 east of the MS RVR. This will
make for a very high average temp for the reporting climate day.

.LONG TERM...(Tuesday through next Sunday)
ISSUED AT 330 AM CST Mon Feb 20 2017

Exceptional record breaking warmth will be with us both Tuesday and
Wednesday, before clouds and precipitation usher in a period of
cooler, but with the exception of Saturday, still ABOVE NORMAL

Tuesday and Wednesday are ideal for warming, with sunshine, west to
southwest winds, and a relatively dry air mass. I still feel we are
likely to exceed our forecast highs, but this is a very challenging
thing to put there in going so far above guidance we are in
unprecedented levels. Thus we can only go so far out on the limb
beyond records and remain confident. In general, we`re looking at a
1 or 2 degree above record forecast for Tuesday, and 3 to 8 degrees
over record forecast for Wednesday. For most sites in our CWA, this
would tie or break the all time (some recently set yesterday) all
time warmest February day.

Wednesday night, the wave passing to the north of the area that
brought the southwest winds for the daytime, will bring a front
south over the area, and that process is expected to be dry.
Cyclogenesis is expected in the plains Thursday, bringing a strong
warm front through the area Thursday and Thursday night, followed by
a low pressure passage toward Friday. This low will be occluding
during this passage timing, thus a challenging forecast includes a
dry slot interaction and possible convection, as well as an eventual
change to snow on the back side Friday night. I do not expect snow
Thursday night, as the warm advection aloft will support wet bulb
temperatures above freezing in our area. Rain, with embedded thunder
is likely, and we should see the greatest coverage for the event in
the north half of the CWA. Any stronger storms would be confined to
the southeast CWA where the warm sector could interact with the dry
slot transition Friday morning. It is too early but a threat for a
strong storm will need to be watched for.

At this point, while the Friday night into Saturday morning period
appears windy and sharply colder, the amount of snow may be very low
in the north.  A wet accumulation around 1 inch may be possible
there, but following a mild day and preceded by an exceptionally
warm week, this will make impacts lower than normal.

Quickly on the heels of the low Friday, will be another warm
advection event Sunday into Monday. For now, this system does not
appear to be as strong as any model forecasted last night, but we
should initially be cold enough for some snow Saturday night and
early Sunday, before a transition to above freezing rain/snow mix
occurs Sunday.  Highs sunday and monday appear likely to be in the
upper 30s to mid 40s, which does not support much winter impacts at
this point.



.AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning)
ISSUED AT 538 AM CST Mon Feb 20 2017

Some MVFR fog getting into the sites this morning, but the more
problematic IFR low stratus with embedded fog is being drawn up in
southeast winds out of central IL will likely impact the MLI site
this morning, before pushing north again by late morning. Then low
VFR to MVFR CIGs midday and into early afternoon before areas of
showers and some thunderstorms sweep in from the west from mid
afternoon and through at least mid evening before passing east of
the TAF sites. Then after a frontal passage mid to late evening
expect low MVFR to IFR stratus and lingering a few hours and
possibly lingering lighter rain, before post-frontal west winds
scoop up cigs from the west to VFR again toward Tue morning. But
low CIGs may linger at BRL and possibly MLI toward 12z Tue
morning. Southeast winds of 10-15 KTS by afternoon and higher
gusts, veering to the west-southwest later tonight after the
showers exit.    ..12..


ISSUED AT 342 AM 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




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