Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 140453

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1153 PM CDT Tue Mar 13 2018


Issued at 325 PM CDT Tue Mar 13 2018

Storm system in the northeast United States was still bringing
cyclonic flow/cold air advection, especially east of the MS River.
Snow showers have been occurring in se WI/ne IL but these have
been staying east of the dvn cwa for the most part, and were
moving southward.

Temperatures this afternoon were in the 30s to lower 40s with
northwest winds gusting to around 30 mph.


.SHORT TERM...(This Evening through Wednesday)
ISSUED AT 325 PM CDT Tue Mar 13 2018

Cold tonight then warmer and breezy on Wednesday.

Tonight: High pressure will be settling over the area with clear
skies, light winds and a very dry airmass in place. This should
allow for ideal radiational cooling with minimum temperatures
dropping to the lower 20s at most locations.

Wednesday: Sunny breezy and warmer as the high slips to our east.
Maximum temperatures should push into the 50s to near 60.
Southwest winds will be gusting to around 30 mph during the
afternoon and with dry grasses there will be a heightened grass
fire threat. However, at this time it looks to be somewhat of a
marginal situation based on current weather conditions.

.LONG TERM...(Wednesday Night through next Tuesday)
ISSUED AT 325 PM CDT Tue Mar 13 2018

Wednesday night and Thursday...Dry FROPA still on track for Wed
evening, with post-frontal northerly flow and cool advection making
for lows down in the in the 20s. Sfc ridge lobe edges down acrs the
upper MS RVR Valley and western GRT LKS for a dry and seasonable Thu
into Thu evening. West central/SW plains low battling the omega
block in place, to try and whirl overrunning precip bands toward the
southwestern CWA by late Thu night, but chances are that drying
easterly boundary flow back from ridge axis airmass source may act
as a hindrance from any precip reaching the sfc in the local area
through 12z Friday morning anyway. If precip does make it to the sfc
in our far southwest, it may be in the form of a wintry mix of ice
pellets, snow and rain.

Friday through Sunday...The same dry easterly fetch will look to act
as a precip-advancing hindrance during the day on Friday, but some
light sprinkles or rain should make into the far southwestern CWA by
late morning into the afternoon. Highs Friday barely making it into
the lower 40s if mid and high level cloud cover thick enough over
cooler east boundary layer(BL) fetch. The central plains low will
look to undercut the lingering omega block ridge and roll east-
southeast in the process somewhere from KS to central or south
central MO by late Sat morning. Still some 12z medium range model
discrepancy how far north or south this process will take, and how
much the local CWA will be impacted by precip will be dependent on
the track. For example, the further south and touch weaker with the
low center 12z GFS, mainly clips the southern third of the DVN CWA
with the northern portion of it`s precip shield Friday night into
Saturday morning. What may start out as rain will look to evapo-cool
or dynamically cool into rain/snow mix or all wet snow parameters as
the night progresses, and suggests areas along and south of a line
from Sigourney IA, to Monmouth in west central IL to get anywhere
from a few tenths of an inch to over an inch of wet snow
accumulation by Saturday morning. It produces a heavy band of snow
of 2 to close to 4 inches acrs the far southern tier of counties.

This in contrast to the further north and stronger 12z ECMWF, which
has a wintry mix up to and even north of I80 Friday night into Sat
morning with some wet snow accumulation possible. With the model
descrepancies, will carry POPs further north with a lean toward the
ECMWF or blend, and will have to watch model trends in low path
handling over the next few days. A continued cut-back on high temp
potential for St Patrick`s Day, and if the further north Euro is
right with lingering clouds and precip fields well into the day, the
fcst temps will still be too mild. Right now Sunday is shaping up to
be a dry, milder and in-between systems day if current
model/ensemble timing is correct.

Monday and next Tuesday...Both the 12z GFS and ECMWF are advertising
a similar wave rolling acrs the midwest somewhere from west-to-east,
again with the Euro a bit stronger and further north than the less
phased and less organized GFS. Both models may have most of the
precip during the day which may lean toward a bias of rain or
rain/snow mix. But the cooler and dynamic ECMWF breaks out wet
snow accumulation even during the afternoon, and lingers into the
evening. The longer the precip lingers into Monday night, the
better the snow accumulation potential will be. Low confidence
with either scenario at this time. Mainly a dry but below normal
temp regime for next Tue behind whatever system can impact the
area earlier on Monday.  ..12..


.AVIATION...(For the 06Z TAFS through 06Z Wednesday Night)
ISSUED AT 1151 PM CDT Tue Mar 13 2018

Surface high pressure building into the area will maintain VFR
conditions through the forecast period. Only concern is gusty
winds during the late morning and afternoon hours. A dry cold
frontal pushing through the area late tomorrow will be
inconsequential with respect to aviation impacts.




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