Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KDVN 231821
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
121 PM CDT Thu Mar 23 2017

.UPDATE...
Issued at 119 PM CDT Thu Mar 23 2017

Based on temperature trends, max temps have been lowered for
today.

UPDATE Issued at 905 AM CDT Thu Mar 23 2017

A rather significant update has been done to the forecast today.
12z sounding shows a deep layer of dry air that will need to be
overcome to produce precipitation today. Some moistening of this
layer will occur as the day progresses.

The initial round of forcing is starting to move east of the area.
Radar shows echoes across northern Missouri are on a decreasing
trend. However, there is a respectable instability gradient that
should allow showers to persist across northern Missouri and
slowly work into the south half of the area later this morning.

So, have lowered pops further for today and have gone with a light
rain/sprinkle regime.

&&

.SYNOPSIS...
Issued at 330 AM CDT Thu Mar 23 2017

At 3 AM CDT...upper midwest under a slowly thickening canopy of
mostly mid to upper level clouds. Satellite, pressure fall centers
and radar all show limited forcing and moisture and along with
high cloud bases, marginal risk of precipitation next 12 to 24
hours. Upstream energy in southwest US and moisture plume in
south plains to arrive in the area late Friday into the weekend.

&&

.SHORT TERM...(Today and Tonight)
ISSUED AT 330 AM CDT Thu Mar 23 2017

Short term forecast confidence assessment...fair or average with 2 issues
if POPS are still too high and drier air allowing for highs to be a
bit milder than forecast. Risk of thunder appears to be quite low attm.

Today...mostly cloudy to cloudy and cool with southeast winds of 10
to 20+ MPH and with thickening clouds. This suggests highs mid 40s
north and northeast to mid to upper 50s far southwest with highs very
late in the afternoon hours to near sunset. POPS have trimmed to 15
to 35 percent and very possibly still too high with isolated thunder
which again also may be too generous due to limited forcing and moisture
even aloft.

Tonight...continue cloudy skies and with low risk of POPS far north
which may be still too generous as forcing likely still further northwest.
Area mins likely early evening as winds shirt to the south with morning
temperatures 3 to 5 degrees higher than early evening.

.LONG TERM...(Friday through next Wednesday)
ISSUED AT 330 AM CDT Thu Mar 23 2017

Friday...Assessing the latest run models in handling slow moving/
rex blocked low acrs the central Plains, seems a bit more of a
southward adjustment(and slowed) with ensemble sfc low placement
acrs north central OK at 00z Sat, then to the Springfield MO area by
12z Sat with inverted trof enhancement to the northeast up along the
MS RVR Valley including the local CWA. Still see a warm sector day
with clouds and shower bands holding off and not spreading in from
the west/southwest until later during the afternoon. Thus more
enhanced mixing into the warm tongue under partly to mostly sunny
skies, would lead to more highs in the way of low to mid 70s, as
opposed to the GFS/NAM mid 60s to low 70s.

Then the warm moist conveyor up off the Gulf enhanced by flow/
moisture pump around western flank of Atlantic ridge, to be
realized later afternoon and especially Friday night. High POPS
for rounds of showers and some embedded thunderstorms warranted
for this period, with PWAT`s of over an inch and indications of
convergent TROWAL feed around the cyclone suggesting several local
areas getting anywhere from three quarters of an inch, to well
over an inch of rainfall by Sat morning. Fcst vertical profiles
and other parameters still suggest minimal threat for any strong
to severe storms Fri evening this far north, unless a dry mid
layer swath can in-spiral into back edge of mid layer moisture
plume. but current progs suggest better chance of that phenomena
to the south acrs KS and MO.

Saturday and Sunday...The main low/circulation path will be a big
player in temps on Sat. The 00z GFS is further north almost into the
souther CWA by late afternoon, while the 00z ECMWF is closer to ST
Louis MO.  While both models would still spiral rounds of showers/or
rain acrs the area in ongoing TROWAL feed making for a wet day, the
further north GFS is quite a bit milder and would also produce a
better shot at some embedded thunder in the southern to central CWA
at times during the day. The further south Euro and it`s east-
northeast llvl flow with LK MI influence, would be quite a bit
cooler...highs of 42 at DBQ and 54 at MLI, while the GFS has 57 at
DBQ and 69 at MLI. Will take a temp blend but trend it more toward
the ECMWF with it`s better track record of handling northeasterly
cool influxes/backdoor fronts better. But again, it`s all in the
cyclone track. May have just a minor temp drop off Sat night into
Sunday morning under ongoing clouds, occasional rain and drizzle, as
well as fog. The rain will look to wind down by Sunday afternoon and
the low fills and lifts off to the northeast, making for milder
temps north of I80 than what occurs on Sat.

Monday through next Wednesday...Longer range trends suggest
westerly, almost split flow pattern to evolve acrs much of the
central and eastern CONUS early in the week, before Pacific wave
inland ingest digs out L/W troffiness again acrs the Rockies into
the mid week. Seasonable or a bit above normal temps this period,
with the southern stream looking to be initially more active and
shuttle passing wave mainly to the south of the region Monday and
Monday night. But the southern CWA still at risk for some shower
activity even if the further south 00Z ECMWF verifies, and will have
to continue to carry POPS early in the week.     ..12..

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
ISSUED AT 1236 PM CDT Thu Mar 23 2017

MVFR conditions will overspread eastern Iowa and northern Illinois
through 00z/24 with pockets of IFR. Scattered showers will be
possible that may organize into a narrow band across southeast
Iowa that moves northeast. If this band develops, then a brief
period of IFR conditions is possible. After 00z/24 conditions will
slowly improve to VFR as a front moves into Wisconsin. LLWS will
also be developing around 00z/24 and continue past sunrise Friday
morning.


&&

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

$$

UPDATE...08
SYNOPSIS...Nichols
SHORT TERM...Nichols
LONG TERM...12
AVIATION...08


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.