Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA
FXUS64 KLIX 270842
Area Forecast Discussion
National Weather Service New Orleans LA
342 AM CDT Thu Oct 27 2016
A weakening upper level trough axis will slide into the central
Gulf Coast today bringing a bit more cloud cover and a slight
chance of a shower or thunderstorm to the area. Overall rain
chances will remain fairly limited due to a pool of dry mid-level
air lingering over the area. However, even with the limiting
factor of drier air in place overall instability values support the
formation of some convection today. Lapse rates are favorable at
around 7C/km and MLCAPE is expected to be between 1000 and
1200J/KG. This instability combined with weak forcing aloft should
be enough to spark off isolated convection. Temperatures will
remain warmer than average with highs rising into the middle 80s.
Heading into tonight, the trough axis will fully shear out over
the northern Gulf and increasing negative vorticity advection and
mid and upper level ridging will overspread the forecast area.
Light winds and high humidity values in the low levels should
support another round of patchy fog tonight. Friday will be
substantially drier and more stable as ridging takes hold aloft
with PW values falling to less and one inch, and MLCAPE values of
300 J/KG or less. Given these parameters, expect to see dry
weather and clear skies on Friday. Temperatures will remain warmer
than seasonal norms on Friday with highs climbing back into the
middle 80s. Similar conditions are expected on Saturday as the
upper level ridge further expands over the region.
No significant change in the upper level pattern is expected on
Sunday or Monday with mostly clear skies, dry weather, and warmer
than normal temperatures forecast both days. Conditions remain
favorable for some patchy fog development both Saturday and Sunday
nights as temperatures cool into the 50s and lower 60s and a low
level inversion forms cutting off the boundary layer winds.
By Tuesday all of the models agree that the upper level ridge axis
should shift to the east of the forecast area. However, there is
little change in the overall moisture field during this period and
a strong mid-level cap should remain in place through Wednesday.
This cap should prevent convective development through the
period. There is enough moisture and instability below the cap to
support suppressed cumulus development each afternoon as
temperatures climb into the middle 80s. Conditions are also still
favorable for fog formation each night due to the high humidity
values in the low levels, strong radiational cooling, and light
boundary layer flow of 10 knots or less.
For the most part, VFR conditions will exist at all terminals after
13z today and again Thursday. FG has developed in a few locations
this morning and this should once again be the case tonight.
Will bring restricted vis to relatively low levels and leave as
TEMPO group for now since it will be hard to find exactly which
terminals will have BKN080 ceilings move through.
Winds will remain lower over protected waters and stronger farther
offshore. A deep fetch of 20+ knot winds outside the local waters
will provide swell to add to the wind wave heights for the next
several days. Winds have stayed around the 15 knot level and seas
remain just outside of caution conditions. Will leave things as is
for now as the previous fcast looks very good. This scenario is
expected to remain for the next several days possibly easing toward
the end of the weekend.
DSS code: Green.
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 84 59 85 57 / 20 10 0 0
BTR 83 62 85 60 / 20 10 0 0
ASD 83 62 84 59 / 20 10 0 0
MSY 82 66 83 65 / 20 10 0 0
GPT 81 63 82 61 / 20 10 0 0
PQL 82 61 84 58 / 20 10 0 0