Area Forecast Discussion
Issued by NWS Little Rock, AR
FXUS64 KLZK 291729
Area Forecast Discussion
National Weather Service Little Rock AR
1229 PM CDT Wed Mar 29 2017
Have placed TSRA chances at sites in line with the latest near
term forecast philosophy. A southeast near surface wind of 10-20
kts will become southwesterly at all sites by 12z/30.
.PREV DISCUSSION...(ISSUED 603 AM CDT Wed Mar 29 2017)
Updated to include the 12Z aviation discussion below...
A warm front will lift north through the state through this
afternoon...with some occasional MVFR VIS/CIGs possible through
this time frame. A complex of gradually weakening SHRA/TSRA are
ongoing just west of the state this morning...which will move
E/NE into WRN sections of the state over the next few hrs. This
activity may impact some WRN/NRN terminals...but activity should
dissipate by late morning. Precip should be fairly isolated
through mid afternoon...but new convection will develop across the
WRN half of the state this afternoon. This convection will move
east through the state this evening and overnight...with a cold
front then pushing east across the state on Thu. Some severe
storms could be seen this afternoon into the overnight hrs.
PREV DISCUSSION...(ISSUED 253 AM CDT Wed Mar 29 2017)
SHORT TERM...Today Through Thursday Night
Early this morning...nearly stationary frontal boundary remains
across SRN sections of the state...with a persistent ERLY wind seen
for most areas across the CWA. Some SHRA have developed north of
this boundary across portions of the NWRN AR Ozarks...though a much
more organized area of convection is ongoing to the west across TX
and OK. Expect some isolated to scattered SHRA/TSRA to continue to
develop across WRN and NWRN sections of the state this
morning...especially as the frontal boundary begins to lift north
across the state by around sunrise. Have slight chance to chance
POPs for this activity...but with increasing POPs across far WRN AR
by around sunrise as the ongoing convection across SRN OK and NRN TX
moves NE towards AR.
This activity will then push east into the WRN counties of the
CWA...but the last several runs of the high-res near-term guidance
keeps suggesting this activity dissipating by mid-morning before
reaching central sections of the state. Keep some lingering chance
pops for late morning as some spotty SHRA/TSRA could continue.
The warm front will have lifted north of the state by late this
afternoon and early evening...with the SFC low lifting from NE OK
into SW MO. Have POPs rebounding this afternoon and especially this
evening as an upper level wave lifts NE over the state...and
SHRA/TSRA develop and become more numerous as forcing aloft
Given forecast MU CAPE values ranging from 1-2k J/kg and 0-6 km bulk
SHR ranging from 45-60 kts...expect potential for some organized SVR
thunderstorms. With the majority of the MU CAPE in the
-10 to -30 C range aloft...combined with some substantial mid-level
dry air...expect large damaging hail as the main threat...along with
damaging winds. Will also see some tornado potential with 0-1 SRH
values over 200 m2/s2...especially across NRN AR in closer proximity
to the SFC low this evening. The tornado threat may also increase
further south as the LLJ increases.
Expect the main area of scattered or more discrete convection to
initiate across WRN and portions of the central sections of the
state during the mid to late afternoon hrs...then become more
widespread or organizing into a linear complex during the evening
hrs as the convection moves east across the state. This primary
wave of convection will move east of the state by around sunrise
Thu...but additional SHRA/TSRA will remain possible along the main
cold front which will surge east across the state by Thu
afternoon. Expect precip chances to then decrease as drier...more
stable air moves into the state to end the forecast.
However...some lingering moisture wrapping around the main low to
the north may keep some SHRA in the forecast for the far NRN
counties during the evening hrs Thu night.
LONG TERM...Friday Through Tuesday
Initially, frontal boundary will be stalled near southern Arkansas
on Friday. By late Saturday or early Sunday, upper flow will
amplify, pushing the surface front northward as a warm boundary. At
the same time, a negatively tilted upper trough will push out from
the southwest and move across the state, generating showers and
thunderstorms on Sunday into Sunday night.
Models are in fairly good agreement during this period, with a
surface low moving into Arkansas on Monday, and a closed off upper
low following suit. With the systems nearly-in phase with each
other, plenty of moisture over the region, and lots of wind shear,
severe storms look to be a possibility should this scenario pan out.
It`s still pretty far out, and we need to watch this period, as the
forecast will likely change somewhat over the next few days.