446 
FXUS64 KSHV 021539
AFDSHV

Area Forecast Discussion
National Weather Service Shreveport LA
939 AM CST Sat Mar 2 2019

.UPDATE...
Removed morning fog out of a large portions of the area, although
left fog in for remainder of the mrng for portions of ne TX,
mainly west of hwy 59. Have made no other changes attm./07/.

&&


.PREV DISCUSSION... /issued 628 AM CST Sat Mar 2 2019/ 

AVIATION...
IFR cigs areawide with patchy mostly mvfr vsbys in drizzle/fog. 
Expect slow improvements to mvfr cigs by 02/18z. NE-E winds will
continue around 5 kts thru most of the 03/12z fcst cycle. Cigs
will begin to lower to low mvfr to ifr by around 03/03z. Expect
widespread rain with ifr cigs and vsbys to begin btwn 02-06/-09z
across the area from the nw. Some embedded tstms possible but
aside from klfk, not mentioned in TAF's attm./07./

PREV DISCUSSION... /issued 424 AM CST Sat Mar 2 2019/ 

SHORT TERM.../Today through Sunday/ 
Low level moisture continues to hang across the region this
morning which has resulted in patchy fog across the region along
with some patchy drizzle. A bit of a range in temperatures this
morning with low 40s north of Interstate 30, where the drier air 
has been in place, and lower 50s across Deep East TX and Central
Louisiana, where the moisture is a little deeper. Patchy fog and
drizzle will continue through mid morning, with some possible
light rain south of Interstate 20, where the deeper moisture is
located. Models suggest there will be a break in the rain today
from Noon through the late afternoon, however clouds and below
normal afternoon temperatures will hang around the region. Highs
today will run from the low 50s north of Interstate 30 to low 60s
across Deep East TX and Central Louisiana. As we move into the
late evening and overnight hours, a weak disturbance will move 
across the region resulting in showers and isolated thunderstorm
development across the region. Effective bulk shear will approach
40 kts along with some marginal lapse rates and low freezing
heights which could result in some marginal severe hail in some 
isolated locations. SPC has issued a Marginal Risk to highlight
this possibility. Widespread showers/t-storms will return again 
on Sunday as weak surface low will move across East TX/North 
Louisiana dragging a strong arctic front across the region. Winds 
will shift to the NW behind the front and temperatures will fall
throughout the day.  With moderate instability (SB CAPE 1000-1500 J/kg) along with strong 
shear (50-60kt 0-6km) across central Louisiana, some strong to 
severe storms will be possible Sunday morning into the early 
afternoon across a corridor between Natchitoches-Grant-Caldwell- 
LaSalle parishes. The primary threat will be damaging winds, but 
an isolated tornado threat could also be possible. The front will 
clear the region by the late afternoon hours, and drier arctic air
will continue to push into the region. /20/

LONG TERM.../Sunday Night through Friday/ 
Cold, arctic air will continue to spill S into the 
region Sunday night in wake of the fropa earlier in the day, with 
the short term progs in good agreement this morning with the 
shortwave trough exiting the area to the E, and the H850 trough 
quickly shifting E into SE TX/S LA. Although cold advection will 
follow the front, the progs depict considerable post-frontal cloud
cover which will linger through the overnight hours Sunday night.
In addition, this air mass will initially be shallow, with cold 
air damming around the higher terrain of the Ouachitas delaying 
the onset of the coldest air until later in the day Monday. Thus, 
have trended a bit warmer than the Blended guidance and closer to 
the MOS numbers for min temps Sunday night, with additional 
elevated cloud cover expected to increase from the W Monday once 
the lower level moisture erodes. The GFS is suggesting this 
morning that weak isentropic lift within this elevated moisture 
lyr might result in some areas of IP across the region, but sfc 
temps are expected to remain well above freezing, this no 
accumulation is expected. 

The GFS/ECMWF are in good agreement with another shortwave trough 
rounding the broad longwave trough over the Plains/MS Valley 
Tuesday, which will reinforce much drier air Swd Monday 
night/Tuesday morning, with the coldest (subfreezing) nights in the 
forecast period expected Monday and Tuesday nights with the arctic 
ridge settling S into the region. Temps should begin to gradually 
moderate by midweek as the sfc ridge begins to shift E of the 
region. In fact, the GFS/ECMWF remain consistent with earlier runs 
with low level moisture quickly advecting NE into E TX Wednesday 
evening, and across the remainder of the region Thursday morning. 
The low level moisture profile is progged to continue deepening 
Thursday along a SWrly LLJ, such that isolated warm advection SHRA 
will be possible over the Wrn half of the region, before expanding 
across the remainder of the area Thursday night. Have continued the 
trend with the previous forecast in maintaining slight chance pops 
Thursday, before raising pops to low chance Thursday night areawide. 
However, the models diverge significantly thereafter with the ECMWF 
the outlier in developing/expanding the warm sector N to near the 
Red River Valley of Srn OK/N TX into the Nrn sections of SW AR 
Friday, whereas the GFS/Canadian continue to suggest a weak cold 
front sliding SE through the area Friday/Friday before pulling up 
stationary over Deep E or SE TX/Cntrl or Srn LA. Have trended the 
end of the extended closer to the GFS/Canadian blend given its run 
to run consistency, thus maintaining chance pops Friday before 
diminishing with the fropa Friday night. However, with the very low 
amplitude noted in the mostly zonal flow over the Srn Plains/Lower 
MS Valley, it remains to be seen whether this front will have enough 
of a push from the attendant shortwave troughing over the 
Plains/Midwest by the end of the week. 

&&

.PRELIMINARY POINT TEMPS/POPS...
SHV  59  50  50  33 /  20  70  70  10 
MLU  59  51  53  32 /  20  70  70  10 
DEQ  53  45  46  25 /  30  70  70  10 
TXK  53  45  46  28 /  30  70  70  10 
ELD  57  46  47  28 /  20  70  70  10 
TYR  55  47  48  30 /  30  70  70  10 
GGG  57  49  50  33 /  20  70  70  10 
LFK  61  56  57  38 /  20  70  70  10 

&&

.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&

$$