Mesoscale Discussion 0443 NWS Storm Prediction Center Norman OK 0710 AM CDT Thu Apr 25 2019
Areas affected...South-Central/Southeast LA...Southern MS
Concerning...Severe potential...Watch possible
Valid 251210Z - 251415Z
Probability of Watch Issuance...60 percent
SUMMARY...Ongoing convective line could pose a downstream severe threat and convective trends will be monitored closely for potential watch issuance.
DISCUSSION...A line of thunderstorms currently extending from central MS southwestward into southwest LA. Most organized portion of this line appears to be over east-central LA where some quicker forward motion has been noted recently. Farther south (i.e. across southwest LA), some upscale growth has been noted although a forward surge indicative more linear organization has not been observed. The precipitation shield moving onshore in south-central LA cast some doubt toward whether or not the areas downstream of the ongoing line can sufficiently destabilize. This precipitation shield also looks to prevent more cellular development within the open warm sector.
Even so, the potential for more organization still exists with a resulting threat for wind damage and a tornado or two downstream across south-central/southeast LA and adjacent portions of southern MS. Convective trends across the region will be monitored closely for potential watch issuance.
Mesoscale Precipitation Discussion 0162 NWS Weather Prediction Center College Park MD 827 AM EDT Thu Apr 25 2019
Areas affected...southern/eastern LA into MS and far western AL
Concerning...Heavy rainfall...Flash flooding possible
Valid 251226Z - 251815Z
Summary...Heavy rainfall may allow for flash flooding in a few locations from southern/eastern LA into MS and far western AL through 18Z. Favorable alignment of heavy rain cores are expected to allow 2-4 inches in 3 hours or less time.
Discussion...Regional radar imagery through 12Z across the Lower Mississippi Valley showed a line of convection with bowing segments moving across central LA into central MS with a general movement off toward the east-northeast at 35-45 kt, roughly aligned with the 850-300 mb mean wind. Dual-pol rainfall estimates and gauge reports within this line were 1-2 in/hr with training at times leading to dual-pol estimated rain between 3-4 inches such as from Madison Parish into west-central MS. 850 mb winds out ahead of the convective line were SSW at 30-35 kt via the KDGX VAD wind plot and RAP analyses. A second area of heavy rain was located out ahead of the convective line, but with less intense rainfall rates assumed given warmer cloud tops on IR imagery, was located along and just offshore of the central LA coast.
A positively tilted shortwave trough axis was seen on water vapor imagery from central AR into south-central TX at 12Z with forecasts showing the southern portion of the trough axis swinging out faster than the northern portion allowing for a more neutral orientation by 18Z. This movement should allow a quicker eastward progression to ongoing convection across the central Gulf Coast for the early afternoon.
Until then however, bowing segments along the main convective line across LA and mS will briefly allow favorable orientation with respect to the 850-300 mb mean and training of rainfall rates of 1-2 in/hr (locally higher at times). This combined with likely intensifying rainfall ahead of the convective line given added diffluence and divergence within the left exit region of a 120-130 kt upper level jet (sampled by 12Z CRP RAOB) will augment updraft strength and may allow for repeated rounds of heavy rain over the next few hours from LA into MS. Flash flooding will be possible with rainfall of 2-4 inches in 3 hours or less which would exceed Flash Flood Guidance in a few locations.
Last Edit: Apr 25, 2019 7:18:30 GMT -6 by SKYSUMMIT
Tornado Watch Number 102 NWS Storm Prediction Center Norman OK 810 AM CDT Thu Apr 25 2019
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of Southern and Eastern Louisiana Southern Mississippi Coastal Waters
* Effective this Thursday morning and afternoon from 810 AM until 300 PM CDT.
* Primary threats include... A couple tornadoes possible Scattered damaging wind gusts to 70 mph possible
SUMMARY...Bands of mostly linearly organized storms are expected to gradually intensify across the region through the late morning and afternoon hours. Strong shear and moderate moisture will support a risk of severe thunderstorms capable of damaging winds and some tornadoes.
The tornado watch area is approximately along and 85 statute miles east and west of a line from 60 miles north northwest of Pine Belt MS to 40 miles west southwest of Houma LA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU2).
REMEMBER...A Tornado Watch means conditions are favorable for tornadoes and severe thunderstorms in and close to the watch area. Persons in these areas should be on the lookout for threatening weather conditions and listen for later statements and possible warnings.
Winter 2019 - 2020 Freeze Days so far: 10
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The National Weather Service in Lake Charles has issued a
* Flood Warning for... Southeastern Rapides Parish in central Louisiana... Southeastern Beauregard Parish in southwestern Louisiana... Northern Evangeline Parish in central Louisiana... Western Avoyelles Parish in central Louisiana... Allen Parish in southwestern Louisiana...
* Until 1030 AM CDT.
* At 823 AM CDT, Doppler radar indicated thunderstorms producing heavy rain which will cause flooding. Estimates of two to three inches of rain have fallen across the area. Rainfall is beginning to diminish but additional rains will maintain the potential for flooding, especially in low areas and along rivers and bayous.
* Some locations that will experience flooding include... Oakdale, Marksville, Bunkie, Oberlin, Glenmora, Moreauville, Cheneyville, Elizabeth, Turkey Creek, Reeves, Dry Creek, Sugartown, Ragley, Effie, Mittie, Grant, Cottonport, Pine Prairie, Mansura and Lecompte.
Turn around, don't drown when encountering flooded roads. Most flood deaths occur in vehicles.