Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 141722

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1222 PM CDT Wed Mar 14 2018


Issued at 257 AM CDT Wed Mar 14 2018

Weak surface ridge is providing ideal radiational cooling setup
with generally clear skies, light winds and dry ground. This
has allowed temperatures to plummet into the lower to mid 20s,
with upper teens in some drainage areas. Only clouds to really
speak of are just of the high and mostly thin variety, which
continue to stream southward into the region ahead of a mid level
trough racing SSE across Manitoba and Ontario provinces. A cold
front attendant to this feature will sweep through the region
by late afternoon through evening. The absence of moisture and
forcing will result in a dry frontal passage.


.SHORT TERM...(Today and Tonight)
ISSUED AT 257 AM CDT Wed Mar 14 2018

Main concern for today is very high fire danger, as winds shift
to SW/W and once again turn quite gusty by afternoon in well
mixed pre-frontal environment leading to a notable and quick warm-
up today while also further drying out fuels. Thus, encouraging
folks not to do any outdoor burning today. For more please refer
to fire weather section below.

Nudged up winds by late morning and afternoon, with forecast
soundings showing around mid/upper 20 kts of wind sustained
through mixed layer with 30-36 kts sitting atop the mixed layer.
Mixing completely dry adiabatically allowing for 70-80 percent of
momentum transfer to surface yields windy conditions by afternoon
of 20-30 mph with the strongest gusts timed at peak heating 2-4
pm. These winds will be from the SW ushering in a quick and
notable warm-up over the past few days. Deep mixing, good solar
insolation, dry ground and SW wind component all present and good
reasons for not being bashful on going at or above guidance for
highs, as models also often struggle or downplay extent of warming
potential in these early season environments. In addition, a well
timed frontal boundary sagging down through our northern cwa
during peak heating will lead to pre-frontal compressional heating
and furthermore reason to side at or above guidance for highs
especially between the Hwy 30 and Hwy 34 corridors, or roughly
between Cedar Rapids to Burlington. Overall, I have highs mainly
in the 50s today, with the warmest readings targeting that
aforementioned pre-frontal heating corridor where I have readings
in the mid 50s to lower 60s.

Tonight, the front will exit by mid to late evening and then
followed by building high pressure. This will lead to a diminishing
of winds and lows once again in the 20s, albeit not quite as cold
as past nights as still enough wind to keep BL mixed to support blend
or on warmer side of guidance.

.LONG TERM...(Thursday through Tuesday)
ISSUED AT 257 AM CDT Wed Mar 14 2018

Complex long term forecast with sensible weather effects expected is
the story here.  Changing model data along with differing solutions
leads to low confidence in the current forecast.  Differences in
guidance means either most of the area sees rain Friday Evening into
Saturday or freezing rain and sleet.  Guidance also has differing
ideas on QPF which would affect expected impacts. After this system,
a short period of quiet weather before anther system approaches the

The first system to affect the area has two different solutions. The
GFS and GEM have a more northerly track, which would bring the warm
sector further north into our area.  On the front end into Friday
AM, the arriving WAA wing will change precip to sleet and possible
FZRA across the far south before temperatures warm above freezing.
Later, as surface temps cool due to wetbulbing, they may drop to
freezing or just below freezing. The ECMWF and NAM are in a southern
more wet camp that would bring sleet and freezing rain to most of
the area. As far what camp is correct, the ECMWF has more run to run
consistency being south. The GFS solution matches the the GEFS
solutions.  That said, its difficult to determine which is correct.
At the current juncture it seemed as though the superblend was the
best idea with small tweaks to top down grids to reduce the amount
of freezing rain across the area. That was a slight nod to the GFS
and GEFS consistency and the fact it is difficult to accumulate ice
near freezing. Expect this forecast to change. At the current time,
it does not appear that any ice accumulations would be more than
0.10 inches.   Across the north where temps may be cold enough up to
1 inch of snow accumulation is possible.

After this, the next system to affect the area will begin Sunday
night into Monday.  There are differences between models as well
here.  Current superblend has the area seeing mostly rain from this
system.  If current guidance holds it appears we will be north of
the main wave and by the time we cool down into Tuesday morning, the
profiles will be conducive to snow instead of FZRA or PL.  This will
likely change as well and needs to be watched, especially if
guidance has run to run consistency.


.AVIATION...(For the 18Z TAFS through 18Z Thursday Afternoon)
ISSUED AT 1220 PM CDT Wed Mar 14 2018

VFR conditions will be seen through 00z/16. A dry front will move
through eastern Iowa and northern Illinois by 03z/15 followed by
high pressure.


Issued at 257 AM CDT Wed Mar 14 2018

Strong gusty SW/W winds by afternoon, mild temperatures, low
relative humidity and dry fuels will result in a very high fire
danger later this morning through afternoon. GFDI values are
near the extreme category across portions of east central and
southeast Iowa this afternoon. Thus, fire threat level will be
rather sensitive to any changes in winds and dew points. Speaking
of dew points, I did lower them a bit from previous forecast and
toward drier MOS guidance with mainly 20s. However, it`s always
a concern in deeply mixed environments and dry ground of see them
dropping lower. This will need to be especially monitored as should
this occur then more of the cwa could be close or into extreme fire
danger supportive of explosive fire growth. The bottom line is that
any outdoor burning is strongly discouraged today, and will be
highlighting threat in HWO, graphical weather story and also expect
SPS to be issued later this morning.




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