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Office: LIX

FXUS64 KLIX 210434 AAB
AFDLIX

Area Forecast Discussion...UPDATED
National Weather Service New Orleans LA
1134 PM CDT Mon Aug 20 2018

.AVIATION...
Currently monitoring pre-frontal convection moving southward
through Mississippi. Convective allowing models show an overall
weakening trend upon approach into KMCB, KBTR and KHDC. Feel not
as optimistic as some cells may pulse in intensity on influences
from warm lake waters when the activity gets closer. Will be
including some mention of TSRA in TAFs in the predawn hours where
complex is expected to have greater impact then show convection at
other locations just after sunrise but terminating rather early.
VFR conditions should then prevail generally 18Z onward at all
terminals as drier air starts infiltrating the region. 24/RR

&&


.PREV DISCUSSION... /issued 657 PM CDT Mon Aug 20 2018/

UPDATE...
Removing the headlines for Flash Flood Watch, which is expiring at
the top of the hour. All products should be updated at 7 pm. 24/RR

DECISION SUPPORT...

DSS code: Green.
Deployed: None.
Activation: None.
Activities: None.

PREV DISCUSSION... /issued 410 PM CDT Mon Aug 20 2018/

DISCUSSION...
Ongoing convection is oriented just like yesterday with a swath
of numerous storms from Baton Rouge to New Orleans and
northeastward. Outside of that zone, storms are much more
scattered and weaker in nature. The likely reason for northern
limitation of coverage is just how far north the high PW's extend.
Recent local RAOB and satellite imagery both confirm column
moisture levels are quite high at around 2.2-2.3". With such a
saturated sounding, you wouldn't think gusty winds would be an
issue, but observations prove otherwise. Thinking that precip
loading is accelerating downdrafts, because dry air aloft isn't
the culprit. The areas with these gusty winds tend to be mostly
offshore. Gusts have been just above 40 mph in marine environments
and mid 30s inland. Coastal locations will see this potential
impact through the afternoon hours as storms persist through a
little past 00Z. Although the threat for flash flooding is
diminishing, will just allow the watch to expire on its own.

Changes will be coming to the forecast going into Tuesday. Closed
low and trough in the upper atmosphere that is currently situated
along the Mississippi River Basin from the Great Lakes to
Louisiana will be shifting east. A cold front associated with this
feature is currently located in central Texas. Showers and
thunderstorms will begin early in the morning across northwestern
zones Tuesday as the boundary approaches. Convection will then
shift south and east during the afternoon hours. Model soundings
show mid/upper level dry air quickly infiltrating the area with PW
already down to 1.5" in Baton Rouge by noon. The front will be
slow to push offshore due to the base of the upper trough quickly
shifting northeast. However, broadening of the western shoulder of
the main trough will completely push in the post frontal air mass
Wednesday. This will bring with it much drier air and knock down
temperatures by a few degrees. The more noticeable change will be
dewpoints and even morning lows could be dropping into the upper
60s for some locations (mainly I-12 and northward). The pleasant
weather will be short- lived however, with moisture and lower rain
chances returning going into this weekend.

MEFFER

MARINE...Previous forecast looks good. Still looks like a weak
front will drift into the area tomorrow and then meander across the
coastal waters. Eventual placement of the front will determine the.SHORT TERM...

DECISION SUPPORT...

DSS code: Blue.
Deployed: None.
Activation: None.
Activities: Locally heavy rainfall and coastal storm wind gusts

&&

.PRELIMINARY POINT TEMPS/POPS...
MCB  73  91  69  90 /  30  40  10   0
BTR  76  91  71  92 /  30  50  10   0
ASD  76  90  72  91 /  20  60  10  10
MSY  80  90  76  91 /  20  60  20  10
GPT  77  90  74  90 /  20  60  20  10
PQL  76  89  72  91 /  20  50  20  10

&&

.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&

$$



Office: LCH FXUS64 KLCH 210411 AFDLCH Area Forecast Discussion National Weather Service Lake Charles LA 1111 PM CDT Mon Aug 20 2018 .DISCUSSION...Surface analysis showing incoming boundary stretching from near Monroe to Lufkin then continuing southwest. Earlier strong convection this evening along pre-frontal trof over north Louisiana into Mississippi has weakened while advancing east and currently seeing much less and weaker activity ongoing. Current forecast does maintain low end pops across the forecast area tonight and seems reasonable. Forecast on track and no update needed. && .PREV DISCUSSION... /issued 658 PM CDT Mon Aug 20 2018/ DISCUSSION... For 00z TAF issuance. AVIATION... Local 88Ds show some convection hanging around, most notably moving into interior sern TX ahead of approaching weak front...have maintained VCTS for the wrn terminals for an hour or so to account. Re-introduced VCSH at KAEX later this evening as high-res guidance indicates a return of scattered convection with FROPA...not sure the front will advance this far swd tonight but elected to insert the slim chance mention just in case. The srn sites all see a return of VCSH after daybreak tomorrow as additional convection could re-develop along the front. 25 PREV DISCUSSION... /issued 308 PM CDT Mon Aug 20 2018/ DISCUSSION... Wx map shows large sfc low over the Plains, with the cool front over N TX. Cooler and drier air behind the front in OK, where mid to upper 70s prevail there. Down here, lower to mid 90s prevail, heat index values in the 100-105 range. Radar showing scattered SHRA/TSRA over the I-10 corridor of SE TX/S LA this afternoon. Expect additional activity further inland in the next couple of hours. For this evening, the cool front will gradually move southeast, with additional showers and thunderstorms possible along and ahead of the boundary. Thus, keeping 30-50% late this evening for this across inland SE TX/C LA. A brief lull expected after midnight, with showers and thunderstorms firing up toward the I-10 corridor southward into the Gulf by Tuesday morning. Behind the front, slightly lower dewpoints should keep morning lows near 70/lower 70s Wednesday through Friday. Afternoon highs will still be in the lower to mid 90 during this period, but the lower dewpoints in the mid 60s/near 70 will keep the heat index lower for these days. By Friday afternoon into early next week, the mid to upper level high expected to build over the southern U.S. with the typical late summer surface high off the east coast. While the upper high over the region usually spells oppressive heat, we should see enough of a southeast flow off the Gulf to bring moisture off the Gulf and the return of scattered afternoon showers and thunderstorms during this period. DML MARINE... Light to occasionally moderate onshore flow will continue as high pressure continues to ridge across the northern Gulf. A frontal boundary will slowly move south over the region Tuesday into Wednesday, accompanied by an increasing chance for showers and thunderstorms. The front is expected to stall over or just south of the coastal waters, bringing a brief period of offshore flow mid-week. The front will gradually dissipate by the end of the week with return flow expected to resume. DML && .PRELIMINARY POINT TEMPS/POPS... AEX 75 95 68 95 / 50 20 10 10 LCH 79 94 74 96 / 20 40 10 10 LFT 77 93 74 95 / 20 40 10 10 BPT 79 94 75 96 / 20 40 20 10 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...None. && $$ PUBLIC...23 FXUS64 KLCH 210454 AFDLCH Area Forecast Discussion National Weather Service Lake Charles LA 1154 PM CDT Mon Aug 20 2018 .DISCUSSION... For 06z TAF issuance. && .AVIATION... Local 88D data and high res forecast guidance indicate the bulk of the convection currently pushing esewd across e-cntl/nern LA will skirt KAEX, but could have enough of an impact over the next few hours to warrant a TEMPO shower mention for now. Otherwise no significant changes to previous TAF thinking with this package...although rain chances for the Acadiana terminals will need to be looked at a little closer with the 12z package as convective potential looks a little better than just a VC mention, but not enough to warrant a full-blown TEMPO for now. 25 && .PREV DISCUSSION... /issued 1111 PM CDT Mon Aug 20 2018/ DISCUSSION...Surface analysis showing incoming boundary stretching from near Monroe to Lufkin then continuing southwest. Earlier strong convection this evening along pre-frontal trof over north Louisiana into Mississippi has weakened while advancing east and currently seeing much less and weaker activity ongoing. Current forecast does maintain low end pops across the forecast area tonight and seems reasonable. Forecast on track and no update needed. PREV DISCUSSION... /issued 658 PM CDT Mon Aug 20 2018/ DISCUSSION... For 00z TAF issuance. AVIATION... Local 88Ds show some convection hanging around, most notably moving into interior sern TX ahead of approaching weak front...have maintained VCTS for the wrn terminals for an hour or so to account. Re-introduced VCSH at KAEX later this evening as high-res guidance indicates a return of scattered convection with FROPA...not sure the front will advance this far swd tonight but elected to insert the slim chance mention just in case. The srn sites all see a return of VCSH after daybreak tomorrow as additional convection could re-develop along the front. 25 PREV DISCUSSION... /issued 308 PM CDT Mon Aug 20 2018/ DISCUSSION... Wx map shows large sfc low over the Plains, with the cool front over N TX. Cooler and drier air behind the front in OK, where mid to upper 70s prevail there. Down here, lower to mid 90s prevail, heat index values in the 100-105 range. Radar showing scattered SHRA/TSRA over the I-10 corridor of SE TX/S LA this afternoon. Expect additional activity further inland in the next couple of hours. For this evening, the cool front will gradually move southeast, with additional showers and thunderstorms possible along and ahead of the boundary. Thus, keeping 30-50% late this evening for this across inland SE TX/C LA. A brief lull expected after midnight, with showers and thunderstorms firing up toward the I-10 corridor southward into the Gulf by Tuesday morning. Behind the front, slightly lower dewpoints should keep morning lows near 70/lower 70s Wednesday through Friday. Afternoon highs will still be in the lower to mid 90 during this period, but the lower dewpoints in the mid 60s/near 70 will keep the heat index lower for these days. By Friday afternoon into early next week, the mid to upper level high expected to build over the southern U.S. with the typical late summer surface high off the east coast. While the upper high over the region usually spells oppressive heat, we should see enough of a southeast flow off the Gulf to bring moisture off the Gulf and the return of scattered afternoon showers and thunderstorms during this period. DML MARINE... Light to occasionally moderate onshore flow will continue as high pressure continues to ridge across the northern Gulf. A frontal boundary will slowly move south over the region Tuesday into Wednesday, accompanied by an increasing chance for showers and thunderstorms. The front is expected to stall over or just south of the coastal waters, bringing a brief period of offshore flow mid-week. The front will gradually dissipate by the end of the week with return flow expected to resume. DML && .PRELIMINARY POINT TEMPS/POPS... AEX 75 95 68 95 / 50 20 10 10 LCH 79 94 74 96 / 20 40 10 10 LFT 77 93 74 95 / 20 40 10 10 BPT 79 94 75 96 / 20 40 20 10 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...None. && $$
Office: SHV FXUS64 KSHV 210459 AFDSHV Area Forecast Discussion National Weather Service Shreveport LA 1159 PM CDT Mon Aug 20 2018 AVIATION... For the ArkLaTex, skies clearing with a fropa past KELD and near KLFK with showers in the vicinity across Toledo Bend country to KAEX with TS movg E. SFC winds N/NW around 5KT, climb winds are N10-20KT and back to W/NW 20-40KT for flight level. Expect FEW CU and W/NW winds TUE around 10KT with some midday gusts less than 20KT. Outlook is for midweek is hot and dry with NE winds on the surface and for climb out with NW light flow abv. /24/ && .PREV DISCUSSION... /issued 950 PM CDT Mon Aug 20 2018/ SHORT TERM... Active night still in progress for North central LA with the tail end Charlie cluster south of I-20 and well east of I-49 moving SE at 25mph. We have had numerous trees down with wind as strong as Hurricane force in Monroe at the airport at 7:38 p.m. There are 3hr grid changes to this moving weather through the overnight, but most of this will fizzle out and east by around midnight aside from a Parish or two. It is 73 now in Idabel, but it is really still warm out where no rain fell ranging all through the 80s. The cold front is swinging low to mid 60 dew points from deep east TX into NW LA and S AR. Not a bad front for August, just not very wet for everyone. /24/ PREV DISCUSSION... /issued 322 PM CDT Mon Aug 20 2018/ SHORT TERM.../Tonight through Wednesday Morning/ Cold front currently along a line from Jacksonville Texas to Shreveport and northeast to Magnolia Arkansas. Convection expected to gradually increase in coverage along the front through the late afternoon into the early evening hours during the time of peak diurnal heating. With upper-trough swinging east across the region in conjunction with the cold front, strong storms producing gusty winds, small hail and locally heavy rainfall may be possible. Conditions to improve overnight with convection forecast to shift south and dissipate. Overnight low temperatures forecast to fall into the mid 60s across the southern Ozarks to the low to mid 70s elsewhere. Otherwise, upper-level ridge to rebuild across the region bringing dry conditions through the remainder of the short term period ending Wednesday morning. High temperatures on Tuesday to range from the upper 80s across the I-30 corridor to the mid 90s across deep east Texas with lows in the upper 60s on Wednesday morning. /05/ LONG TERM.../Wednesday through Monday/ Most of the long-term forecast period will be dominated by a strong upper ridge that will gradually move directly over the ArkLaTex region. By Wednesday, a broad surface high pressure originated from Southwest Canada will move in the Mid Mississippi River Valley. Northerly surface flow will result in dry air advection across the region and will keep Gulf moisture cut off from the area. Combined with deep layer subsidence from the upper ridge and surface high, dry weather is expected for Wednesday. Daytime high temperatures will generally range from mid to upper 80s in Southeast Oklahoma to mid 90s along and south of Interstate 20. However, the dry air advection should keep heat index values below 100 degrees F. On Thursday, the surface high will move into the Upper Ohio River Valley, and a shortwave trough will move across the Northern Plains. There still remains a slight chance that convection that develops over Oklahoma may affect portions of Southeast Oklahoma and extreme Southwest Arkansas during the daytime hours Thursday. However, every subsequent run of the GFS has been trending closer and closer to the precip-free solution of the ECMWF. Slight-chance PoPs will be maintained with this forecast, but I would not be surprised to see them removed entirely in later issuances. By Friday and into the weekend, the center of the upper ridge move overhead and towards Northeast Mississippi by Monday. Depending on the ridge's exact position, on-shore flow will resume, which should bring back chances for daily diurnal thunderstorm chances associated with the sea breeze. Otherwise, with rain chances overall being slim to none, the heat will be on. Daytime high temperatures will likely climb into the upper 90s and possibly near or just over 100 degrees by Saturday. CN && .PRELIMINARY POINT TEMPS/POPS... SHV 74 94 70 95 / 10 10 0 0 MLU 73 93 68 92 / 70 10 0 0 DEQ 66 88 67 90 / 0 10 0 10 TXK 70 90 68 91 / 10 10 0 0 ELD 70 92 67 91 / 10 10 0 0 TYR 72 95 68 94 / 10 10 0 0 GGG 73 95 69 94 / 10 10 0 0 LFK 76 96 70 96 / 30 10 0 10 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 24/05/09