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

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FXUS64 KLIX 230934

Area Forecast Discussion
National Weather Service New Orleans LA
334 AM CST Thu Jan 23 2020

Large precipitation shield developing over east Texas and western
Louisiana spreading steadily westward ahead of low pressure system
currently over the Texas Hill Country. Temperatures on both sides
of system don`t differ much, with limited low level baroclinicity
and cyclogenetic and frontogenetic forcing taking place on modest
trough amplification aloft. This should be enough to maintain
steady omega response for widespread rainfall today through upper
trough passage later this evening. Models are in pretty good
agreement with the progression of the low and attendant rainfall
but ECMWF may be a bit slower on the back end. Nonetheless, the
rain should taper during the evening hours and be east of the
forecast area by midnight. Given only subtle cold air advection,
some fog may develop due to residual moisture after the rains end
but should dissipate through topside warming/deposition process in
the overnight hours. Friday is expected to be mostly sunny and dry
with temperatures rebounding into the 60s over much of the
forecast area. Optimal radiational cooling takes place Friday
night for lows in the mid 30s to mid 40s from north to south.
Saturday will likely start out sunny but clouds to increase as
next low pressure system begins cyclogenesis process in the west

Models have gotten more agressive in blossoming elevated
convection in advance of gulf low pressure area Saturday night and
spreading eastward for a soggy Sunday and Sunday night before the
surface low moves well east to pull rain out of the area Monday
morning. Some modest surface high pressure builds in the wake with
neutral advection and a rather quick return flow becoming
established Monday night as high frequency / short wavelength
upper level pattern presents yet another low pressure system
developing in the Plains States Tuesday, with subsequent frontal
passage through the area Wednesday. 24/RR


While all locations are currently VFR, rain falling into drier air
below is gradually building ceilings downward, with MVFR to high end
IFR ceilings likely by the 15-17z time frame. Eventually, ceilings
likely to fall into the high end IFR range prior to 00z. Anticipate
occasional reductions in visibilities later in the day as well.
While thunder is not currently mentioned in forecast, there is
lightning associated with precipitation to the south of KLCH, so
threat by afternoon is definitely non-zero. Day shift will monitor
to see if threat has increased. Any significant improvement in
ceilings is not likely until at least 24/06z, and probably not until
after 24/12z.  35


Some wind response to developing low pressure system over Texas
but somewhat disrupted warm frontogenesis to compress the
gradient. Consensus model guidance is not quite high enough to
support Small Craft Advisory headlines, but should easily prevail
in the 15-20 kt range. Therefore, cancelled the SCA and replaced
with "Exercise Caution" headlines for the coastal waters west of
the mouth of the Mississippi River. High frequent pattern will see
winds slack to lighter levels briefly before returning to moderate
onshore flow ahead of next system developing Saturday night, and
yet another one Tuesday night. None of the three systems look
particularly strong, but a duration of moderate wind enhancement
can be expected as the systems race eastward. 24/RR


DSS code: Blue.
Deployed: None.
Activation: None.
Activities: Forecast support for Stennis Space Center.
            River Flood Warnings

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; Marginal risk severe or excessive rain.
Yellow = Heightened impacts with short-fused watch, warning or
         advisory issuances; radar support for slight risk severe
         or excessive rain.
Orange = High Impacts; Enhanced risk severe; nearby tropical events;
         HazMat or other large episodes.
Red =    Full engagement for Moderate to high risk of severe and/or
         excessive rainfall, or direct tropical threats; Events of
         National Significance.


MCB  61  43  60  38 / 100  10   0   0
BTR  66  44  62  39 / 100  10   0   0
ASD  64  45  63  39 /  90  30   0   0
MSY  65  48  62  45 / 100  20   0   0
GPT  61  47  61  41 /  90  30   0   0
PQL  63  47  64  39 /  90  50   0   0




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