Area Forecast Discussion
Issued by NWS Little Rock, AR

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FXUS64 KLZK 251041 AAA
AFDLZK

Area Forecast Discussion...UPDATED
National Weather Service Little Rock AR
541 AM CDT Tue Apr 25 2017

.DISCUSSION...

Updated to include the 12Z aviation discussion below...

&&

.AVIATION...

Some patchy fog will remain possible at ADF through just after
sunrise. Otherwise...VFR conditions will continue through this
afternoon and evening. SRLY winds will be seen...with some gusts
over 20 kts possible. Overnight tonight...expect low level
moisture to increase...with MVFR CIGs and some potential for SHRA
increasing.

&&

.PREV DISCUSSION...(ISSUED 342 AM CDT Tue Apr 25 2017)

SHORT TERM...Today Through Wednesday Night

Dry and calm conditions are ongoing across the CWA early this Tue
morning. This will change by this evening and especially for Wed as
a potent storm system moves through the region.

SFC low pressure will develop on the Leeward side of the Rockies to
the west of AR this afternoon...with a tightening SFC pressure
gradient developing over the state. This will allow for increasing
SRLY winds across the CWA...with some breezy conditions possible.
Winds will hover right below Lake Wind Adv...so have held off on
posting headlines at this time. If winds become more intense than
currently forecast...may need to issue a Lake Wind Adv. These SRLY
winds will also allow for temps to warm into the mid 70s to mid 80s
this afternoon.

Overnight...moisture levels will increase across the region ahead
of an approaching upper level shortwave trough exiting the SRN
Rockies. Chances for precip will remain limited through early Wed
morning...but WRN sections of the CWA may see some isolated to
scattered SHRA and a few TSRA develop before sunrise Wed.

As the upper level shortwave approaches during the daytime hrs on
Wed...SFC low pressure will intensify further just west of AR...with
a deep moisture surge expected for Wed afternoon. SHRA/TSRA will
become more numerous throughout the day...likely organizing into a
linear MCS by late afternoon and through the evening hrs as the
upper level trough axis approaches and becomes negatively tilted.
The SFC low will deepen further as a result...with winds ahead of
the main front turning further SE resulting in increasing low level
SHR.

Forecast MU CAPE values range from just under 2000 to over 3000
J/Kg across the CWA...and when combined with 0-6 KM SHR of 55-70
kts...organized storms will be seen as the increased forcing
approaches from the approaching negatively tilted trough.
Initially...some discrete storms will be possible ahead of the main
front...and will see potential for all SVR WX hazards including
tornadoes with this activity. As the main line of convection along
the front surges ENE...the primary SVR WX hazard will transition to
damaging winds. However...given some indications of high 0-1 km SRH
ahead of this line...brief tornadoes will remain possible along the
leading edge of this linear/quasi-linear area of convection.
Finally...some heavy rainfall will also be seen...but will only see
an isolated flash flood threat with the Wed/Wed night front as it
will be moving east fairly rapidly.

By late Wed night...the front and most if not all convection will
have moved east of the CWA. Drier and much calmer conditions will
then be seen leading into the first part of the long term period.

LONG TERM...Thursday Through Monday

Upper low pressure will be over the northern U.S. to begin the long
term period. The main low will move north of the Great Lakes
Thursday and another low develops over the Rockies on Friday with
southwest flow over Arkansas. This low drops south into Texas
Saturday before ejecting northeast Sunday. Northwest flow returns to
Arkansas on Monday.

Surface high pressure will be over Arkansas Thursday but will not
stick around long. This high moves off to the northeast Thursday
night. A warm front is expected to be over north Arkansas Friday
with the next cold front across Oklahoma and Texas. Little movement
of the cold front is anticipated through Saturday but will move
through Arkansas early Sunday. Severe thunderstorms are expected
with this front and heavy rainfall will result from the slow
movement of the front. Good rain chances are expected Friday and
Saturday then will decrease on Sunday. High pressure will return for
Monday with dry conditions. Temperatures will be above normal Friday
and Saturday, otherwise they will be below normal.

&&

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

$$

Aviation...62



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