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Office: LIX

FXUS64 KLIX 110844
AFDLIX

Area Forecast Discussion
National Weather Service New Orleans LA
344 AM CDT Thu Aug 11 2022

.SYNOPSIS...

Already seeing a significant surge of convection northward from
the Gulf of Mexico to the south of Interstate 10, primarily over
southeast Louisiana. This is several hours earlier than what
we've seen the past couple of mornings. With precipitable water
values in excess of 2 inches, will be continuing to monitor for
the potential of brief street flooding. At this point, convection
is moving, so as long as training doesn't develop, most areas will
be able to deal with one surge.

&&

.SHORT TERM (through Saturday)...

The upper flow continues to shift to a more northwesterly flow
over the next several days as the upper ridge over Colorado
extends southeastward toward the area. This will combine with
upper troughing over the Great Lakes and New England to push a
frontal boundary toward the area. By Saturday, the weakening
surface boundary will be approaching the northern portion of the
area, which could provide a bit of drying by that point.

Until then, the threat of daily thunderstorms will remain high
across the area, with most areas seeing at least some rain each
day. Little change in precipitable water values is noted today and
tomorrow, so with deep tropical moisture (PWATs above 2 inches)
remaining in place, some thunderstorms could drop 2 inches or more
of rain in less than an hours time. If that occurs over an urban
or poor drainage area, brief street flooding is likely. Overall
threat doesn't rise to a large scale Flash Flood Watch, but the
threat is certainly non-zero. Daily convective timing has
generally been late morning through late afternoon, with not much
occurring beyond sunset. However, coastal areas could see
convection as early as sunrise or even before, on Friday morning,
similar to what's occurring this morning.

With widespread clouds/precipitation the next couple days, most
areas will see high temperatures remain in the middle and upper
80s. As convective coverage lowers a little on Saturday, a few
more locations may sneak into the lower 90s. There wasn't much
need to adjust NBM numbers as guidance is in pretty good
agreement. 35

&&

.LONG TERM (Saturday night and beyond)...

As the ridge to the northwest builds southeastward a little bit,
the surface boundary to the north will sag southward a bit.
Precipitable water values as noted in forecast soundings should
lower into the 1.6 to 1.8 range by late Saturday or Sunday. While
this won't cut off convective development completely, it should
lower the areal coverage of the daily thunderstorms on Sunday,
Monday and perhaps Tuesday before moisture levels creep back up
toward 2 inches. The threat of very heavy rainfall should also
diminish accordingly. Haven't departed from the NBM PoPs much at
this point, but wouldn't be surprised to see those numbers drop a
bit in the next day or two. With the diminished areal coverage of
storms, that'll probably tend to allow high temperatures to creep
back into the lower 90s over a larger area, especially Monday and
Tuesday.

&&

.AVIATION (valid through 12z Friday)...

Very localized LIFR or lower conditions likely at KMCB through
about 13z this morning. Other concern will be convection, which
will be in progress at New Orleans terminals and KASD prior to
sunrise, producing IFR or lower visibilities and MVFR ceilings.
Beyond the early morning convection, there will be a continued
threat of TSRA for most or all of the daytime hours before
diminishing near sunset. VFR conditions during the evening hours,
with some potential of a repeat of low conditions at KMCB between
06z and 12z Friday. Low conditions at other terminals beyond 06z
will be more dependent on where significant rainfall occurs during
the day today. 35

&&

.MARINE...
Outside of showers and thunderstorms, mostly benign marine
conditions through the rest of the week and into the upcoming
weekend. The region will sit on the western periphery of the
persistent subtropical high over the western Atlantic, which will
only provide light to moderate southerly winds. Ridging to the
northwest of the area will try to nudge into the area toward the
end of the weekend, but won't have a significant impact over the
next few days.  Otherwise, in and around convection expected
brief heavy rainfall, cloud-to-water lightning, and perhaps a
waterspout or two. With the elevated tides and persistent (albeit
relatively light) southerly winds, expect some minor coastal
flooding during high tide cycles for at least one more day today.
Extended the Coastal Flood Advisory through 00z this evening, as
the high tide cycle will occur at midday today in some areas, and
the resulting high water will take several hours to drop off.
Tidal ranges start to diminish on Friday as we head toward neap
tides, so we may not need to go beyond today with the advisory. 35

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  87  70  86  70 /  80  40  80  20
BTR  89  73  88  73 /  90  30  80  20
ASD  88  73  88  73 /  90  40  80  30
MSY  87  75  86  75 /  90  50  90  30
GPT  86  75  86  75 /  90  60  80  30
PQL  85  73  86  74 / 100  60  80  40

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...Coastal Flood Advisory until 7 PM CDT this evening for
     LAZ066>070-076-078.

GM...None.
MS...Coastal Flood Advisory until 7 PM CDT this evening for
     MSZ080>082.

GM...None.
&&

$$



Office: LCH FXUS64 KLCH 111555 AFDLCH Area Forecast Discussion National Weather Service Lake Charles LA 1055 AM CDT Thu Aug 11 2022 .DISCUSSION... The inverted trough feature this morning looks to be from roughly southwest Mississippi extending southward east of the Atchafalaya Basin into northern Gulf. With forecast area on the west side of the trough, northerly flow is noted and this has helped enhanced the land breeze activity with most nocturnal activity still occurring over the coastal waters. 14Z upper air sounding from KLCH confirms latest LAPS data with PWAT around 2.05 inches which is just over the 75th percentile level of SPC daily climo. Best moisture at the moment according to LAPS and GOES is close to the trough axis and over south central Louisiana with PWAT over 2.25 inches and over the 90th percentile of SPC daily climo. Shower activity has taken longer to develop this morning over land as extensive low clouds and fog has delayed good daytime heating. However, now that the low clouds are dissipating, convective temperatures in the upper 80s should be met shortly after noon time. The 14Z upper air sounding also showed some dry air intrusion just above 70H. However, expecting the deeper moisture to drift westward helping to increase layer moisture and PWAT over the remainder of the forecast area. Therefore, still expecting widespread coverage of showers and thunderstorms by mid afternoon. Main hazards again will be locally heavy rainfall and frequent cloud to ground lightning. Rua && .PREV DISCUSSION... /issued 731 AM CDT Thu Aug 11 2022/ DISCUSSION... For the 08/11/2022 1200 UTC TAF package. AVIATION... The morning TAF package is complex as areas battle extremely low ceilings and visibilities to M1/4 miles at times. Visibility conditions should improve over the next few hours as sunlight can mix out the lowered cloud deck. Otherwise, a full day of rain showers and thunderstorms is expected across all terminals with the best-guess timing for storms falling between 19 and 01Z. Convection will dissipate slowly after sundown, ending by 02 to 03Z. Guidance is interested in another round of dense fog, and with conditions tonight looking similar to the night before, there may be some weight to its thoughts. Due to this, BR was mentioned at all terminals prior to 12Z tomorrow morning. 11 PREV DISCUSSION... /issued 425 AM CDT Thu Aug 11 2022/ SHORT TERM [Today through Saturday]... A weak thunderstorm complex associated with an inverted trof in the northern Gulf has developed over south central Louisiana which has spread inland somewhat. Expect more showers and thunderstorms to develop over coastal waters and spread north over the next several hours as the trof stalls over the area. Even further storm coverage will spread across the region throughout the morning as diurnal effects add further instability to the rich airmass at the sfc. Fcst soundings for this airmass show very high PWAT values (~2.25 inches) which point to very efficient rain- making storms as we've seen in the days prior. Other parameters point to a fairly benign weather day otherwise with elevated winds likely only found local to stronger storms. Wash-rinse-and-repeat for Friday and Saturday as the inverted trof lingers over the region. Similar parameters will be in place, lending to the idea that widespread coverage of storms with heavy downpours being expected for both days. As far as temperatures go, upper 80s to low 90s are expected over the next several days thanks to widespread cloud cover and rain- cooled air. 11 LONG TERM [Sunday through Wednesday]... As we begin the long-term portion of the forecast period, the area looks to finally be seeing the departure of the disturbance over the wrn Gulf of Mexico which has been delivering significant moisture and associated rainfall. This feature is progged to move ashore somewhere along the middle/lower TX coast, to be replaced by mid/upper-level ridging which will begin building back over the region from the Plains with heights beginning to build aloft. Sunday POPs over the nrn 1/3 of the area finally decline to more seasonal values, while over the srn areas, rain chances remain somewhat elevated compared to seasonal normals with higher moisture and less capping. Rain chances then further diminish a little for the early part of the new work week with the ridge gaining more control over the region. Best rain chances remain over lower Acadiana/swrn LA coastline where best moisture/least capping linger. However with reduced rain chances and cloud cover, the heat makes a return to the forecast, especially over the far nwrn zones where highs are progged to nudge back into the mid/upper 90s by Tuesday. POPs creep back upward a bit for Wednesday as a cutoff low sitting over the St. Lawrence Valley sees a series of shortwaves rounding it, breaking down/retrograding the ridge, weakening the cap built up earlier in the week. 25 MARINE... Surface high pressure will continue to ridge across the northern Gulf of Mexico and maintain a light to occasionally moderate onshore flow through the next several days. Scattered showers and thunderstorms will continue in the coastal waters through much of the upcoming week, especially through the morning hours each day. Expect elevated winds and seas near storm activity. 11 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...None. && $$
Office: SHV FXUS64 KSHV 111532 AFDSHV Area Forecast Discussion National Weather Service Shreveport LA 1032 AM CDT Thu Aug 11 2022 ...New UPDATE... .UPDATE... Issued at 1027 AM CDT Thu Aug 11 2022 Slightly updated and massaged afternoon high temperatures based on morning observations and high-res guidance. /44/ && .SHORT TERM... (Thursday through Friday) Issued at 333 AM CDT Thu Aug 11 2022 Low to mid 70s for most sites with 70 at Magnolia the coolest and 77 at Henderson, with not enough rainfall yet, for the warmest. Their radar bin on our 88D storm total precip is less than a tenth in Rusk County. We have had pretty good afternoon coverage over the last couple of days may be close again today, but shifting southward out of our I-30 corridor today and into our Friday shifting across the I-20 corridor. QPF totals will be down from the last two big days for some locales. The cold front lies along the Red River of OK/TX and snakes around our little weather speed bump otherwise known as the Ouachitas. Low to mid 60 dew points are running too shallow for much of the Natural State for that matter, but the NE winds are filtering over OK and much of AR. We will see a light NE wind filter down into the four state area as the 1020mb high over KN/MO makes it's closest pass. However we will keep the 1016mb contour along I-20 with equalizing high pressure off the 1017mb over the Gulf. The northeast winds will only slowly feed slightly drier air into the area, thus keeping some chance pops going even into tomorrow afternoon. Overall our temperatures will stay pat another day and we may see a bit more patchy fog around this time tomorrow. /24/ && .LONG TERM... (Friday Night through Thursday) Issued at 333 AM CDT Thu Aug 11 2022 We begin the long term portion of the forecast with a broad ridge of high pressure aloft centered aross the Central/Southern Plains, into the eastern Rockies with this ridge axis extending south and east into the Lower Miss Valley. While the broad trough of low pressure will have moved south and west of the region by Saturday, there should be enough residual moisture in place in combination with daytime heating to produce isolated afternoon convection across our far southern zones on Saturday. This ridge axis shifts slowly westward by Sunday which should end the diurnally driven convection chances but reintroduced them as we move into Monday as the ridge axis continues to shift westward and a weakness drifts south and east along the back edge of the ridge that could provide enough lift with heating for a return to at least isolated convection coverage across our far northern, eastern and southern zones. Beyond Monday, there are some timing discrepancies in the medium range concerning precipitation chances Tue thru Thu of next week. The ECMWF is quicker to introduce sufficient upper forcing, backdooring itself into our region from the northeast in reaction to a broad trough of low pressure centered across the Upper Great Lakes and New England into the Ohio and Tennessee Valleys. The GFS picks up on this feature but is much later in the week bringing some organized convection into our region. For Tue thru Thu of next week, went with slight chance variety pops for Tue and low end chance pops for Wed and Thu until the medium range comes into better agreement temporally. At least our west and northwest third will be near Heat Advisory criteria in the Monday-Tuesday timeframe given the upper ridge position and forecast ambient temperatures but depending on the timing of the precipitation chances next week, clouds and precip will likely help to taper temperatures late in the extended. /13/ && .AVIATION... (12Z TAFS) Issued at 656 AM CDT Thu Aug 11 2022 For the ArkLaTex terminals, bouncing on this freshly wet soil LIFR in KMLU/KTXK and some mixed bags to come for a couple of hours. Low in the Gulf with a weak wave & front to the north has our skies with lots of debris and new showers cropping up near KELD/KMLU already. Expect more VCSH to crop up as the air destabilizes and eventually thunder. Models looking at one more push from the NE as high pressure arrives in E AR. This air mass just lifts away over the wknd with isold pop-ups we dry out again. /24/ && .PRELIMINARY POINT TEMPS/POPS... SHV 93 73 94 73 / 50 20 30 20 MLU 90 73 91 71 / 70 30 40 20 DEQ 91 68 93 70 / 10 0 10 0 TXK 91 72 93 72 / 30 10 10 0 ELD 89 70 90 68 / 50 20 20 10 TYR 94 74 93 75 / 30 10 20 20 GGG 94 73 93 73 / 40 20 20 20 LFK 94 74 91 74 / 50 30 50 20 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ SHORT TERM...44 LONG TERM....19 AVIATION...44