Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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FXUS63 KDVN 200009
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
609 PM CST Sun Feb 19 2017

...AVIATION UPDATE...

.SYNOPSIS...
Issued at 314 PM CST Sun Feb 19 2017

Yet another day of record breaking warmth across the area as
afternoon readings were in the 60s to lower 70s under mostly sunny
skies. As of 2 pm, record highs have been matched or exceeded at all
four climate sites. Moline had reached 74, exceeding the February
all time record high of 73, tied just 2 days ago. The difference
from the past few days was the increasing low level moisture, as
evident by dewpoints rising into the 40s on light southerly winds
south of a weak warm front bisecting the area from NW to SE across
eastern IA into northern IL. Further south and southwest into this
airmass, dewpoints were in the 50s over NW MO into eastern KS, where
an area of stratus and fog was holding temperatures in the 50s and
60s in a stronger southerly flow ahead of upper trough and
developing frontal system over the rockies.

&&

.SHORT TERM...(This Evening through Monday)
ISSUED AT 314 PM CST Sun Feb 19 2017

The string of dry and sunny weather comes to an end Monday as deep
moisture advancing toward the region brings fog and clouds tonight,
then showers and possible thunderstorms Monday. Forecast challenges
center initially on fog tonight, then timing and coverage of rain
Monday. Temperatures throughout the short term will remain well
above average and possibly record breaking again Monday.

Tonight, initially clear skies and increasing moisture will be
favorable for fog, initially over northern Illinois closest to the
departing ridge axis where fog was thickest this morning. Have
mentioned patchy wording for now as confidence is not high due to
the light but increasing southerly surface winds. Focus will then
turn to the thicker moisture and potential for low stratus and fog
that is expected to spread into much of the forecast area toward
morning, which has been added. Increasing dewpoints and high level,
then mid level cloud cover will result in much warmer mins than the
past several nights, from the lower 40s northeast to the lower 50s
southeast.

Developing forcing, moisture advection and elevated instability will
then support scattered showers, initially over the west in the
morning, spreading east during the day and high pops are maintained.
The potential for thunderstorms, based on elevated instability,
looks low and will keep slight chance/isolated wording. The deep
southerly flow will pull in a moisture rich airmass from the Gulf of
Mexico. Precipitable water values over 1 inch along the TX coast is
shown by the GFS and WRF/NAM overspread the forecast area by Monday
afternoon, which would be well over 300 percent of normal. The
relatively fast moving showers and round of forcing should keep
daytime QPF contained to a range of roughly .25 to .50. Looking at
temperatures, the cloud cover and showers will prevent today`s
extreme warmth from reoccurring. However, advection of the southern
plains airmass, where temperatures today were well into the 60s even
with cloud cover and higher relative humidity, will again threaten
vulnerable February 20th record highs, as referenced in the climate
section.

.LONG TERM...(Monday Night through Sunday)
ISSUED AT 314 PM CST Sun Feb 19 2017

Record warmth through Wednesday then a turn toward much colder
weather later in the long term.

Monday night: Widespread rain and a few embedded thunderstorms
during the evening will gradually end from west to east after
midnight, as the upper level trough/surface trough shifts off to our
east. Additional rainfall should be a quarter of an inch to nearly
1/2 inch especially along and east of the Mississippi River, with
less amounts to the west. Lows will be mainly in the 40s.

Tuesday through Wednesday: Record highs look to be in jeopardy at
all locations during this time frame. In fact, records may be
shattered on Wednesday by at least 5 degrees!  Low pressure in the
Northern Rockies will push across the upper Midwest with a southwest
wind and plenty of sunshine which should be an ideal set-up for
unseasonably warm temperatures. Remains to be seen how moist the
ground will be from Monday`s rain and exactly what the dewpoints
will be at midweek. A wetter ground would prevent temperatures from
really soaring, but we will see. As of now, the grids will have
afternoon highs in the mid 60s along Highway 20 to the lower 70s
along and south of Interstate 80.

Thursday through Friday: This marks the transition to a more active
weather pattern, along with much colder temperatures and potential
for snow through the remainder of February and into early March.
First up will be an intense cyclone that will be coming out of the
southern Rockies and tracking into the Midwest. The ECMWF takes the
low (985 mb) into northeast IA by 12z (6 am) Friday, while the GFS
has the low in extreme northeast MO. Strong warm air advection will
develop rain and a few thunderstorms along and north of a strong
warm front lifting towards the cwa. This would be especially true
Thursday afternoon and Thursday night. If the ECMWF is correct the
dvn cwa will get into a dry warm sector on Friday but moisture is
limited until the system shifts well to our east. The more southern
track of the GFS would keep our area more in the rain with the warm
sector to the south and east. Temperatures will be trending colder
with the streak of record highs only a memory.

Friday night into Saturday: Deformation zone will push across the
cwa with colder temperatures and light snow. However, any
accumulations appear to be light at this time but confidence is low
concerning the exact changeover from rain to snow. Highs on Saturday
will be only in the 30s.

Sunday: The ECMWF streaks an area of light snow across MO with the
northern fringe reaching into portions of the dvn cwa. On the other
hand, the GFS has the bulk of the snow across eastern IA and
northern IL with the potential for some accumulation. Confidence is
low this far out.  Models indicate another strong storm system
around February 27-28.

Haase

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
ISSUED AT 555 PM CST Sun Feb 19 2017

MVFR fog expected develop overnight. There is a low probability
of dense fog due to the increasing SE wind. MVFR clouds will
follow after 12z with showers and isolated thunderstorms
developing after 15z. Will refine favored time periods for
afternoon thunderstorms with next issuance.

&&

.CLIMATE...
ISSUED AT 314 PM CST Sun Feb 19 2017

Record Highs for today, February 19th...

Moline.........69 in 1930
Cedar Rapids...68 in 1930
Dubuque........63 in 1930
Burlington.....70 in 1930

Record Highs for February 20th...

Moline.........65 in 1930
Cedar Rapids...60 in 1981
Dubuque........61 in 1981
Burlington.....67 in 1983

Record highs for February 21st...

Burlington.......68 in 1983
Cedar Rapids.....68 in 1983
Dubuque..........63 in 1930
Moline...........66 in 1930

Record highs for February 22nd...

Burlington.......66 in 2000 (and previous)
Cedar Rapids.....64 in 1984
Dubuque..........61 in 1984
Moline...........66 in 1922

&&

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

$$

SYNOPSIS...Sheets
SHORT TERM...Sheets
LONG TERM...Haase
AVIATION...RP Kinney
CLIMATE...Sheets/Haase



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