Area forecast discussion
National Weather Service Shreveport la
442 am CDT sun may 19 2013
Discussion...
the morning low stratus has just begun to spread north into East Texas/north la
early this morning...and should advect north across the remainder of the
area through sunrise...scattering out by middle to late morning. The
pressure gradient will begin to tighten up by middle-morning across the
Southern Plains...ahead of a 998mb surface low that will drift east over southern Kansas/northwest
OK along the dry line once it mixes east into west-central OK/northwest Texas this
afternoon. Lake Wind Advisory criteria should be met across all of East
Texas/southeast OK...however have expanded the current advisory east into portions
of extreme SW Arkansas and western la as wind gusts to 25-30 miles per hour will be
possible. Otherwise...persistence in temperatures will be the rule today once
the low stratus scatters out...with maximum temperatures nearing or exceeding 90
degrees areawide. The short term forecasts remain consistent with The Rockies
upper trough drifting east and closing off over western NE/South Dakota today...with a
middle level shortwave/speed maximum rounding the trough across central OK into
eastern Kansas this afternoon and evening. Strong diurnal heating and
resultant MLCAPES exceeding 3000-3500 j/kg within in strongly sheared
environment will result in scattered strong/severe convection developing once
again this afternoon in vc of the dryline...which should advance east-northeast
across northwest Texas/OK/cntrl plains late this afternoon and evening...before
diminishing later tonight with the loss of heating and boundary layer
stabilization. Can/T rule out some of this convection migrating east into
extreme southeast OK/adjacent SW Arkansas tonight...although in a weakened
state...thus have retained slight mention probability of precipitation for these areas.
The pressure gradient will again tighten across the Southern Plains Monday
as surface low pressure deepens once again along the dry line...this time
farther S across the upper Red River valley of northwest Texas in response to
strong heating...such that another lake Wind Advisory will likely be
needed across much of the area. Scattered strong/severe convection should again
fire near the dryline from northwest Texas into central OK/southeast Kansas Monday afternoon
as the primary trough beneath the South Dakota/NE closed low rotates east into the
southern rockies. This convection should advance east-northeast from North Texas through much
of OK/northwest Arkansas Monday night...with its remnants again possibly reaching
southeast OK/extreme NE Texas/SW Arkansas late. Have increased probability of precipitation slightly to middle
chance across southeast OK...with this convection weakening as it approaches
the area again given the stabilizing boundary layer. However...this
convection could very well end up leaving remnant convective boundaries in
vc of the I-30 corridor Tuesday morning...which will focus more
organized convection Tuesday afternoon/night as heating/resultant
instability is maximized...and large scale forcing increases with the
approach of the upper trough as it moves into the Southern Plains.
Have beefed up probability of precipitation to likely for southeast OK/northern sections of SW Arkansas Tuesday
afternoon and night given the better model consensus...with a
developing south-southwest low level jet aiding in a potential mesoscale convective system development from SW Arkansas
into NE Texas Tuesday night. Severe potential appears to ramp up Tuesday
afternoon and evening as MLCAPES rise to 3000-3500 j/kg across southeast OK/SW
Arkansas/NE Texas. This mesoscale convective system should shift southeast into north la early Wednesday and
gradually weaken...and thus have kept high chance probability of precipitation going for this
area although the convection should diminish from west to east during the
afternoon and evening with the departure of the upper trough.
Northwest flow aloft will follow the trough passage Wednesday as upper
ridging develops over much of the plains beneath the upper Midwest
trough...and a closed low entering the Pacific northwest. A weak but persistent
srly low level flow may be enough to enhance the development of scattered
convection over OK/Arkansas Thursday through Saturday as embedded shortwave
perturbations drift southeast atop the upper ridge axis...and beneath the
Midwest trough. Thus...have added slight chance probability of precipitation for this time
period mainly over the NE half of the area. Temperatures through the middle and
late week /extended/ timeframe should remain slightly above normal.
Prelims to follow below...
15
&&
Aviation...
morning low clouds...rising north from the coast....becmg patchy
over East Texas lakes and central la. Deepening surface low over upper Red
River valley will pull increasing south winds into area today...15
to 25 kts and gusty over NE Texas this afternoon...and around 15 kts over
kmlu and keld this afternoon. Strong mixing will yield scattered cumulus by around 15z
today. Low clouds returning quicker tonight...between 07-09z Monday...with
south winds overnight around 10 to 15 kts. /Vii/
&&
Preliminary point temps/pops...
shv 90 72 89 73 88 / 5 5 5 10 30
mlu 89 72 89 72 88 / 5 0 5 5 20
deq 89 71 87 70 82 / 5 20 10 30 60
txk 90 72 88 72 85 / 5 10 10 20 50
eld 89 72 89 71 87 / 5 5 5 10 40
tyr 91 72 90 73 86 / 5 5 5 10 30
ggg 91 72 90 73 87 / 5 5 5 10 30
lfk 91 72 90 73 89 / 5 5 5 10 20
&&
Shv watches/warnings/advisories...
Arkansas...lake Wind Advisory from 10 am this morning to 8 PM CDT this
evening for the following zones: arz070-071.
La...Lake Wind Advisory from 10 am this morning to 8 PM CDT this
evening for the following zones: laz001-002-010-011-017.
OK...lake Wind Advisory from 10 am this morning to 8 PM CDT this
evening for the following zones: okz077.
Texas...Lake Wind Advisory from 10 am this morning to 8 PM CDT this
evening for the following zones:
txz096-097-108>112-124>126-136>138-149>153-165>167.
&&
$$
15/07
