Area Forecast Discussion
Issued by NWS Little Rock, AR

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FXUS64 KLZK 261130 AAA

Area Forecast Discussion...Update
National Weather Service Little Rock AR
630 AM CDT Sun Mar 26 2017


Overall VFR flight conditions are forecast today, except for parts
of northern AR Taf sites where MVFR ceilings will be seen for part
of the morning. These ceilings are associated with the large surface
low pressure center over the upper Plains, which will gradually move
and thin this morning. Winds will be northwest to west at less than
10 mph or light and variable. Winds will become more south at 5 to
10 mph through the day. (59)


.Prev Discussion.../ Issued 332 AM CDT Sun Mar 26 2017/

Main concerns in this forecast cycle are chances of convection
late Sunday night to Monday, then next chance Wednesday night to
Thursday. Both weather system will have some chance of strong to
severe storms. Over temperatures will be above normal.

Currently high pressure is filtering in over AR, as the cold front
pushes more east, and the surface low pressure system moves
northeast. Some lower clouds were seen over northern AR, while to
the south skies have cleared. Dewpoint temperatures and air
temperatures were both in the the 40s to lower 50s. Winds were
light from the west or light and variable. Aloft, the upper low
continues to move northeast, while upper high pressure ridging is
seen over the central Plains.


.SHORT TERM...Today Through Monday Night

The active progressive upper pattern will continue over central to
southern US, and will bring repeated systems to the region. Today
will be a dry with the winds gradually becoming south, and
temperatures warming to the 70s to lower 80s. Tonight, the next
upper and surface systems move into OK then lift northeast to MO.
Convection chances come up quickly overnight and into Monday for
AR, especially over northern AR where the main lift is forecast to
move across. Moisture maybe a limiting factor with a quick moving
system and limited time to set up a south wind flow. Dewpoint
temperatures only make it to the 50s. 06Z to 12Z Mon appear to be
where factors max. together to possibly develop strong to severe
storms. SPC does have a marginal to slight risk of severe storms
with this system. Hail and winds will be the main threats, while
an isolated tornado may form. Monday during the day, the focus of
any strong to severe storms moves east, then out of the state
Monday afternoon. Highs on Monday will be above normal values with
the 70s to lower 80s. Dry weather returns Monday night with
clearing skies, and lows in the 40s northwest, the 50s central to
the 60s in the far south.


.LONG TERM...Tuesday Through Sunday


The consensus of model guidance indicates that a cold front will
stall out near the Arkansas and Louisiana border around sunrise on
Tuesday. Upper level ridging is expected to build over Arkansas on
Tuesday as a powerful upper level storm system continues to move
east over the southwestern CONUS towards the South Plains. With dry
air in place behind the front and upper level ridging over the
state... expect a very pleasant day across the state with highs in
the mid-70s under partly cloudy skies.


The GFS and ECMWF are now both on board in bringing the upper level
trough over the South Plains on Wednesday as one large upper trough
as opposed to breaking into two distinct pieces of energy like the
GFS was advertising yesterday on its 00Z run. In general this large
scale solution increases confidence in the potential for severe
storms across Arkansas Wednesday late afternoon and evening. For
Wednesday...both models have the warm sector in place for all but
far northwestern Arkansas. Both models show strong deep layer shear
and a sufficient amount of convective potential instability to
support supercell thunderstorms. It`s too early to determine the
mode of the convection...but the synoptic conditions are favorable
for severe storms so will highlight this risk in graphics and the
Hazardous weather outlook.

Aside from the severe thunderstorm threat...there is also a threat
for heavy rainfall and flash flooding. The raw QPF output from the
26/00Z GFS paints a big swath of 3-4 inch rainfall totals in 6 hours
across parts of central and western Arkansas Wednesday evening.
While this raw model output from one model run is unlikely to does at least demonstrate the potential for heavy
rainfall and flash flooding across the state. The GFS seems to be
more aggressive with the heavy rainfall threat than the ECMWF
because the GFS is a bit slower with the eastward progression of the
upper trough. Both models significantly slow down the eastward
progression of the upper trough as it detaches from the polar jet
stream...however a slower solution will keep favorable dynamics in
place over the warm sector for a longer period of time that would
support a local flash flood event. Deep moisture as indicated by
PWAT values of greater than 1.5 inches is present in each the ingredients are certainly in place and we will
have to watch the flooding potential closely moving forward.


The GFS and ECMWF both show the potential for another
round of strong to severe thunderstorms primarily over southeast
Arkansas Thursday early afternoon. There are many reasons why this
may not pan will not highlight a severe weather threat on
Thursday right now. If the deterministic thermodynamic and kinematic
parameters from the GFS at 18Z pan out...we would certainly have a
severe weather threat in southeast Arkansas. However significant
organized convection on Wednesday and Wednesday evening will likely
have a large impact on where storms set up on Thursday. It seems
more likely that numerous showers and thunderstorms across Arkansas
Wednesday and Wednesday night will tend to push the severe weather
threat southeast of the state by Thursday...but we will continue to
monitor model solutions as this storm system approaches.

Friday and Saturday...

Behind the Wednesday/Thursday upper level
storm system...dry air advection and large scale forcing for
subsidence should lead to a couple of days of dry weather for Friday
and into the weekend. Temperatures look like they will top out in
the lower 70s for most locations...making for a couple of very nice
days for anyone with plans outdoors.


Another strong upper level storm system is expected to move
over the South Plains on Sunday. This could bring another round of
showers and thunderstorms across Arkansas...however there is
considerable uncertainty regarding this system at this time. Went
ahead with some chance POPs for now...but the timing of
precipitation could change quite a bit in later forecasts.


Batesville AR     73  56  72  55 /   0  50  70  30
Camden AR         81  62  77  57 /   0  30  50  20
Harrison AR       70  53  70  50 /   0  80  70  20
Hot Springs AR    78  59  76  53 /   0  60  60  10
Little Rock   AR  78  59  75  54 /   0  40  70  20
Monticello AR     79  61  75  61 /   0  20  50  30
Mount Ida AR      77  58  76  51 /   0  60  50  10
Mountain Home AR  70  53  72  53 /   0  70  70  30
Newport AR        73  57  73  57 /   0  50  70  40
Pine Bluff AR     78  60  76  59 /   0  30  60  30
Russellville AR   77  57  76  51 /   0  70  70  10
Searcy AR         75  56  73  54 /   0  50  70  30
Stuttgart AR      76  60  74  57 /   0  40  60  40

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


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