Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kdvn 172355 

Area forecast discussion
National Weather Service Quad Cities Iowa Illinois
655 PM CDT Thu Oct 17 2019

..aviation update...

issued at 153 PM CDT Thu Oct 17 2019

A ridge of surface high pressure is responsible for the light
winds and clear skies today, and it continues to be generally be
found along the axis of the Mississippi River.


Short term...(this evening through friday)
issued at 153 PM CDT Thu Oct 17 2019

Tonight, the high pressure should remain close enough to allow
winds to decouple this evening, for lows quickly dropping to the
mid 30s east to lower 40s west. After midnight, the increasing
gradient winds should mix the boundary layer enough to stabilize
the drop.

Friday, the winds should be strongest in the west, with sustained
winds approaching 20 kts in the afternoon, and around 15 kts east.
This breeze, combined with ample sunshine, should allow for
highs to approach 70 in many areas, especially west, and the mid
60s east. We may see some gusts around 40 mph for a brief time in
the far northwest, and that's likely going to result in an Special Weather Statement
issuance, but not advisory. Wind direction should be south to
southeast, not normally conducive for deep enough mixing for
advisories to be warranted.

Long term...(friday night through thursday)
issued at 153 PM CDT Thu Oct 17 2019

Moisture will be returning by Friday night, and by Saturday
morning, there should be a narrow band of rain along the cold
front moving through the during day. Models are greatly uncertain
on how much forcing and moisture are available along the front.
The most aggressive models such as the NAM/namnest produce a solid
band of 0.25 to 0.50" rains through The Heart of the County Warning Area and
dissipate the band before exiting to the east. Other mesoscale models,
such as the nmm and arw are dry, as is the global Gem. The GFS and
ec are in the 0.10 to 0.25 ballpark, thus there is no support for
heavy rainfall. This event should not impact our rivers in any
way, assuming it remains under 0.5 in all areas as expected. The
rains will end by Saturday evening, after a relatively cool and
cloudy day.

The fast moving progressive synoptic pattern will reload a western
trof by Sunday. This will provide mild and breezy weather to the
area Sunday through Monday, and cool conditions Tuesday and
Wednesday. Rainfall will once again be battling what could be
strong forcing, but a narrow moist tongue followed by a dry slot
with that synoptic low moving to the northwest. Amounts of rain
for what could be a less than 12 hour event, should be limited,
and I agree with wpc reducing rainfall to under 0.5 for this
event. Any robust thunder should be confined to the southern
Mississippi Valley, where MUCAPE is more likely to be over 1000,
while up here it looks limited and again, a very brief window just
ahead of the dry slot arrival Monday.

With 60s in place for Sunday and Monday, and 50s in place for
Tuesday through Thursday, for highs, this will be a week that
continues to represent typical Fall weather, with plenty of wind,
and temperature fluctuations.


Aviation...(for the 00z tafs through 00z Friday evening)
issued at 639 PM CDT Thu Oct 17 2019

VFR will prevail through the period with southeast winds increasing late
tonight into Friday morning. Gusty winds, between 22-28 kts, are
expected for the afternoon. Low-level wind shear is anticipated
Friday night - mostly beyond this taf period.


Dvn watches/warnings/advisories...


National Weather Service Glossary of Abbreviations