Area Forecast Discussion
Issued by NWS Little Rock, AR

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FXUS64 KLZK 212352 AAA

Area Forecast Discussion...UPDATED
National Weather Service Little Rock AR
552 PM CST Tue Feb 21 2017


Updated for the 00z aviation discussion below.



In general, expect a marked decline in flight categories this
evening. All sits are expected to dip down to at least IFR levels,
with central and northern sites going to LIFR around/after
midnight as areas of dense fog develop in saturated low level air
mass with light winds. Do have prevailing 1/2sm - 1/4sm
visibility in at central and northern locations, with ceilings
below 300 ft AGL overnight. Confidence is pretty high in dense fog
developing. A return to VFR levels should occur between
16z-20z Wed as drier air begins to filter into Arkansas in


.PREV DISCUSSION...(ISSUED 247 PM CST Tue Feb 21 2017 )

Short term...Tonight through Thursday night...

Biggest concern this period will be dealing with an upper level low
passing to the south of the state. With all short term models in
basically good agreement with this feature, will simply blend
forecast solutions this afternoon.

Cut off upper low clearly seen on moisture channel imagery this
afternoon and is currently straddling the Arkansas/Louisiana
border. System expected to move east and then southeast and just
to the south of Mobile Bay by Wednesday morning.

Moisture continues to wrap around the departing system with numerous
showers across the county warning area. Airmass is stable enough
that thunderstorms are not expected although a clap of thunder or
two can be totally discounted. Shower activity will continue
through early evening before starting to wane and a pre-tonight
period will be added to the forecast. Moisture looks to remain deep
through the night with little if any clearing and fog formation is

In the wake of the upper low, weak upper ridging will move in for
Wednesday and with quasi-zonal flow in place aloft, highs in the mid
70s should be common across the state. Meanwhile, low pressure will
kick out of the Rockies on Thursday and be located in the central
high plains by the end of the period. Southerly flow will get
cranking for Thursday and record breaking temperatures will be
within grasp.

Cold front associated with the system Thursday/Thursday night will
be over northwest Oklahoma by the end of the period and forecast to
come through in the extended period.  Mav/Mex numbers look good and
are generally accepted.

Long Term...Friday thru Tuesday...

Primary concern at the beginning of the extended term will be
relating to fire weather conditions. A front will be pushing through
the state during the day, bringing much cooler and drier air to the
region, along with gusty winds.

Afternoon RH values will drop down into the 30 percent range, and
west to northwest winds will be gusty, especially during the
afternoon hours.

The second issue of note will be a return of freezing temperatures
to the state. On Saturday night temperatures across the northwest
half of the state are expected to drop down below the 32 degree
mark. In an ordinary February this would not be of much
significance, but due to the unseasonably warm weather of late, this
may catch some residents by surprise.

With little snow cover to the north - you have to go all the way to
northern Minnesota and northern North Dakota right now to find any,
the impact of the cold front will be significantly lessened. By
Monday the surface high will settle to the east, bringing a return
southerly flow to the area. Afternoon high temperatures on Thursday
will be back up into the 70`s across much of the state.

With the return flow in place on Monday and Tuesday, and a swly flow
aloft, I went ahead and went with the consensus model guidance of 20-
30 POPs across much of the area. This seems reasonable given the
likelihood of shortwaves rippling out ahead of the next trof taking
shape in the swrn Us.


.LZK Watches/Warnings/Advisories...NONE.


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