FXUS64 KLIX 212054
Area Forecast Discussion
National Weather Service New Orleans LA
354 PM CDT Mon Aug 21 2017
No significant changes in the forecast through Wednesday. An upper
level low pressure system will continue to push westward from the
central Gulf of Mexico into the western Gulf by Wednesday. This
will be the main feature driving our weather through the middle of
the week as deep tropical moisture feeds into the area. This
increase in available moisture combined with decent forcing aloft
associated with the passing trough axis will be enough to drive
increased convective activity beginning tomorrow and persisting
into Wednesday. Expect to see convective coverage increase from
the isolated showers and thunderstorms observed today to more
numerous showers and thunderstorms by Wednesday. The convective
activity will be tied to the amount of instability in the airmass,
so the highest POP values will tend to be during peak heating
hours from late morning through the early evening. A convective
minimum over land should occur from late evening through the early
morning hours when temperatures fall into the 70s and CAPE values
decrease. Over the water, convective activity should actually
peak during the early morning hours when overall instability
values will be greatest due to the warmer ocean temperatures and
slight cooling aloft associated with the loss of solar insolation.
Temperatures will fairly close to average through the short term
period with highs in the lower 90s and lows in the 70s.
The forecast for the latter part of the workweek and the upcoming
weekend looks to remain unsettled as two distinct features work in
tandem to produce ample forcing throughout the atmospheric column
and keep ample deep tropical moisture in place over the region.
The first of these features is the lingering upper level trough
moving through the western Gulf of Mexico and into Texas. This
trough and the related tropical moisture axis will linger over
the Gulf South through the weekend. This feature alone would keep
elevated POP values in place. However, a well defined low level
boundary will also slide in from the north in the form of a weak
front and then stall along the Gulf coast. This boundary should
serve as a low level focus for convective activity, and could
contribute to higher potential for locally heavy rainfall events
if the wind field turns supportive for backbuilding thunderstorm
development. The high atmospheric moisture content of 2.2 to 2.3
inches is also supportive of some locally heavy rainfall events
occurring over the latter part of the week. Due to the increase in
expected cloud cover and rainfall, temperatures should average a
few degrees cooler than normal. Highs in the upper 80s and lows in
the lower 70s can be expected from Thursday through Sunday.
Isolated to locally scattered SHRA/TSRA will briefly impact KHDC,
KHUM, and possibly the vicinity of a couple other airports during
the remainder of the afternoon. Otherwise, VFR is expected to
prevail at most TAF airports, however a brief period of MVFR
conditions in light fog is expected late tonight and early Tuesday
morning mainly at KMCB and KHDC. Isolated to scattered convection is
again expected with daytime heating Tuesday, so later TAF issuances
will need to address this. 22/TD
Outside of thunderstorm activity that could produce locally higher
waves and gusty winds, the weather pattern across the coastal
waters will remain fairly benign through the end of the week.
Winds should remain at 10 knots or less, and the wind field will
be highly variable as the landbreeze/seabreeze cycle dominates the
nearshore waters. Given the light wind field, seas should remain
relatively calm at 1 to 3 feet through the week.
DSS code: Blue.
Activities: DSS support for NOHSEP; Monitoring Convective trends.
Decision Support Services (DSS) Code Legend
Green = No weather impacts that require action.
Blue = Long-fused watch, warning, or advisory in effect or
high visibility event.
Yellow = Heightened impacts with short-fused watch, warning or
advisory issuances; radar support.
Orange = High Impacts; Slight to Moderate risk severe; nearby tropical
events; HazMat or other large episodes.
Red = Full engagement for Moderate risk of severe and/or
direct tropical threats; Events of National Significance.
.PRELIMINARY POINT TEMPS/POPS...
MCB 74 93 73 90 / 20 40 30 60
BTR 75 92 75 92 / 20 40 30 60
ASD 77 92 76 94 / 30 40 30 40
MSY 78 91 78 93 / 30 30 30 40
GPT 78 90 77 91 / 30 30 30 40
PQL 76 91 76 91 / 30 30 30 40
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