Area Forecast Discussion
Issued by NWS New Orleans/Baton Rouge, LA

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FXUS64 KLIX 060745

Area Forecast Discussion
National Weather Service New Orleans LA
245 AM CDT Thu Aug 6 2020

.SHORT RANGE (Today through Saturday Night)...

Current synoptic overview early this morning shows the same
subtle, nearly stationary trough axis parked across the northern
Gulf coast which is reflected well from 850mb well to the upper
troposphere, with our CWA on the upstream side of the axis owing
in largely NW to WNW flow aloft. Yesterday the advertised MCS did
drop south across LCH`s CWA delivering strong storms, with
convective development across SE LA well in line with what was
forecast by short-range CAM`s. This MCS eventually decayed and
now keeps a relatively messy anvil canopy across parts of our
area. Remnant outflow boundaries across our marine zones combined
with ample marine instability will help develop some spotty storms
later this morning through the early/mid morning hours. Most
convection will remain offshore or near coastal SE LA and
southern MS and may contain gusty downdraft winds. Additionally, a
few isolated waterspouts will be possible as a surface vorticity
max resides just across the MS sound and coastal SE LA north of
the mouth of the MS yielding in a small spike of Non-Supercell
Tornado parameter values in the 3-4 range. This convection will
die off around mid-morning as we warm up across land areas.
Looking like the same areas as yesterday will see another round of
heavy rain and a strong storm or two but mostly confined to near
coastal locations of SE LA and into coastal marine zones. Keeping
the higher PoP bias against NBM guidance going in these areas,
but opted against heavier coverage that recent HRRR trends are
portraying, instead kept in 30-40% PoP`s in these areas today.

Not much changing going into Friday and Saturday, as a weak
surface high drifts off to the east along with the same
aforementioned weak trough axis eventually decaying. This is due
to a strong ridge building deeper in heights across the central US
which is slowly expanding east. Isolated afternoon pop-up t-storm
chances slowly spread north each day beginning Friday and
especially into Saturday as we begin see a steady trend in deeper
Gulf moisture building north. However, with H5 heights building
may lead to a steady increase in heat. NBM guidance suffers here,
and have pulled up afternoon highs generally in the mid 90`s for
areas inland away from the coast. This build up in temperatures,
along with surface moisture puts afternoon max heat indicies in
the 103-106F range, generally below Heat Advisory Criteria but
will monitor guidance/trends closely in case anything changes. KLG

.LONG RANGE (Sunday through Thursday)...

Not much change to the extended forecast as models continue to be in
good agreement that the upper pattern will flatten through second
half of the weekend and into the work week. A weak trough...more of
a weakness between ridging over the western Atlantic and SW CONUS
will be left behind over the local area. In the lower levels,
extension of the Bermuda high meanders through the northeastern Gulf
keeping the local area in a generally onshore flow regime with
access to plenty of moisture.

All that being said, expect a continued trend toward typical
summertime weather. POPs will gradually increase through the first
part of the week, trending from lower end chance POPs around 25-30
percent on Sunday to solid 50 percent POPs by Wednesday. The
increased cloud cover and rain chances should help keep afternoon
highs in check, trending slightly downward from the low to mid 90s
on Sunday to the upper 80s to right around 90 by Wednesday.




Expect VFR conditions for all terminals through the forecast
period. Only exception will once again be KHUM where isolated TSRA
is expected to develop between 19-20Z this afternoon. Included
VCTS to account for the spotty nature of the expected convection,
with the main threats in any one storm being gusty, downdraft
winds and temporary reductions in VIS. Otherwise, any storms will
dissipate around sunset revealing ongoing VFR conditions
overnight. KLG



Main focus for this morning will be spotty t-storms across just
about all SE LA and southern MS coastal zones. Threats associated
with any one stronger storm will be gusty, erratic surface winds
as well as isolated waterspouts. This activity will dissipate
around mid-morning revealing dry and calm conditions tonight and
into Friday. Weak onshore flow develops Friday lasting through the
weekend and into next week with no hazardous weather expected in
this time frame. KLG


MCB  92  71  93  73 /   0   0  10   0
BTR  93  70  95  73 /   0   0  10   0
ASD  94  71  94  74 /   0   0  20   0
MSY  93  76  93  76 /   0   0  20   0
GPT  92  75  90  76 /   0   0  20   0
PQL  97  73  97  73 /  10  10  20   0



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