dimanche 14 avril 2019
Apr 14, 2019 1300 UTC Day 1 Convective Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Sun Apr 14 2019 Valid 141300Z - 151200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE WESTERN CAROLINAS TO PORTIONS OF PENNSYLVANIA AND OHIO... ...SUMMARY... Severe thunderstorms are forecast today in parts of the Ohio Valley southward through the southern Appalachians and northeast Gulf Coast. Severe thunderstorms are possible this evening/tonight east of the Appalachians from the Carolina Piedmont northward into parts of the Mid-Atlantic states. ...Synopsis... In mid/upper levels, a synoptic-scale trough is evident in moisture- channel imagery from MN/IA across the Ozarks and southwestward over south TX, with embedded vorticity max and remnant low over the western Ozarks region. This trough will move east-northeastward to a 00Z position from Upper MI to the IL/IN border, western TN, MS, and southeastern LA. By 12Z the trough should lost amplitude, but still remain large and well-defined, from southern ON to WV, the Carolinas, and southern/eastern GA. At the surface, 11Z analysis showed an elongated surface cyclone in the PAH-MEM corridor. A more-coherent low is forecast to consolidate through midday then move northeastward to near the CLE/ CAK area by 00Z, then over or very near VT by 12Z. The associated leading cold front was drawn from the low across northern/ southwestern AL and south of southeastern LA over the Gulf. A secondary/reinforcing cold front extended southwestward over AR. By 00Z, the main front should reach eastern OH, WV, the western Carolinas, and central/southern GA. By 12Z, the front is forecast over the southeastern NY/NJ area, then over Atlantic waters to south FL. A warm front, drawn initially in wavy fashion over eastern TN and western/northern NC -- will shift northward erratically through the afternoon, catching up to a synoptic boundary initially extending from the low east-northeastward across northern portions of KY/WV/MD. The combined warm front then should move northward through much of the Mid-Atlantic region. ...Upper Ohio Valley, Mid-Atlantic to southeastern CONUS... Scattered thunderstorms are expected to move from southwest to northeast across the outlook area through this evening, offering a primary threat of damaging to severe gusts, but with a few tornadoes also possible. A broken, messy band of precip and embedded thunderstorms is ongoing ahead of the front from portions of southeastern TN across the western FL Panhandle, with at least isolated severe potential remaining in a low-CAPE/high-shear setting. Refer to the remaining portions of watches 57-59, and accompanying mesoscale discussions, for more on the near-term scenario. An extensive shield of clouds/precip is apparent in a prefrontal low-level warm-advection/moisture-transport zone from eastern TN northward over much of KY/OH/IN. A narrow corridor of destabilization is expected behind this precip and ahead of the low/front today, related to pockets of surface-diabatic heating and theta-e advection in the warm sector. This and weak MLCINH will offset modest midlevel lapse rates enough to support scattered thunderstorms along/ahead of the surface cold front, including prefrontal confluence/convergence lines. Convection generally will assume quasi-linear configurations with embedded LEWPs, bowing segments, and perhaps a few supercells possible. The environment will be characterized by strong deep-layer/speed shear and modest but sufficient buoyancy, with 500-mb winds strengthening to more than 70 kt over much of the central Appalachians region, and 45-60 kt of 850-mb flow crossing the same area. Buoyancy fields will be rather fragmented, but with general 500-1000 J/jg MLCAPE values spreading northeastward over eastern KY/OH and over areas from the Blue Ridge eastward. A relative min in low-level theta-e and buoyancy is likely in higher elevations from southwestern VA northeastward, but with at least marginal instability to support convection. Bands of convection should shift/form east of the mountains with time as well, also offering a dominant wind threat and secondary tornado potential in the strong-shear environment. Overall severe potential is expected to diminish after dark, and as the stronger upper support and mass response ejects northeastward in step with the trough aloft. ..Edwards/Wendt.. 04/14/2019
samedi 13 avril 2019
NWS Forecast Office Little Rock, AR
A strong storm system will bring showers and thunderstorms to the region this weekend. Some of these storms could be strong to severe Saturday afternoon through the evening hours generally south of a Texarkana to Little Rock to West Memphis line. The primary concern at this time is strong winds but tornadoes, some strong, will be possible across far southeastern Arkansas.
NWS Forecast Office Jackson, MS
A significant severe weather outbreak is likely this afternoon into early Sunday morning. Tornadoes are likely throughout the entire region with some strong and long track tornadoes possible. Large hail and damaging wind gusts will be a significant threat as well. We advise everyone to stay weather aware this afternoon and overnight!
NWS Lake Charles
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTHEAST TEXAS AND WESTERN/CENTRAL LOUISIANA... Severe thunderstorms will be possible Saturday afternoon/evening from southeast Texas northeastward through Louisiana and into parts of the Tennessee Valley. All modes of severe weather will be possible. This includes damaging winds, hail, tornadoes, and flash flooding.
NWS Forecast Office Shreveport, LA
There is a risk for severe storms across much of Four State Region today and into this evening. The main threat this morning will be large hail and damaging winds. However, the threat will increase this afternoon during peak daytime heating. Tornadoes, large hail, damaging winds, and locally heavy rainfall will be possible. The severe weather threat should diminish by late this evening.
Public Severe Weather Outlook (PWO) https://www.spc.noaa.gov/products/outlook/pwo.html
https://www.spc.noaa.gov/products/outlook/archive/2019/pwo.mp4ZCZNote: Multimedia briefing MP4. Please note the briefing may be out of date 5 hours after its issuance and there will be no subsequent updates during the day. Please send comments or questions to spc.feedback@noaa.gov or via the feedback page.
View What is a Watch? clip.
C SPCPWOSPC ALL
WOUS40 KWNS 130742
ALZ000-ARZ000-LAZ000-MSZ000-TXZ000-131800-
PUBLIC SEVERE WEATHER OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0242 AM CDT SAT APR 13 2019
...Severe thunderstorms expected over parts of the East Texas to
lower Mississippi Valley region later today and tonight...
* LOCATIONS...
Central and northern Louisiana
Mississippi
East Texas
Southern Arkansas
Western Alabama
* HAZARDS...
Several tornadoes, a few intense
Widespread damaging winds
Scattered large hail, some baseball size
* SUMMARY...
Numerous severe thunderstorms capable of producing tornadoes,
wind damage and large hail, are expected across parts of east
Texas, Louisiana, southern Arkansas, Mississippi, western
Alabama and surrounding areas today and tonight. The greatest
risk is from east Texas to central Mississippi.
Preparedness actions...
Review your severe weather safety procedures for the possibility
of dangerous weather today. Stay tuned to NOAA Weather Radio,
weather.gov, or other media for watches and warnings. A tornado
watch means that conditions are favorable for tornadoes to form
during the next several hours. If a tornado warning is issued for
your area, move to a place of safety, ideally in a basement or
interior room on the lowest floor of a sturdy building.
&&
..Edwards.. 04/13/2019
Current Mesoscale Discussions
Mesoscale Discussion 0315NWS Storm Prediction Center Norman OK 0450 AM CDT Sat Apr 13 2019 Areas affected...portions of west-central Texas southward toward the Rio Grande Concerning...Tornado Watch 49... Valid 130950Z - 131045Z The severe weather threat for Tornado Watch 49 continues. SUMMARY...The severe threat continues across WW 49. DISCUSSION...Convection has generally struggled to deepen across the WW area this morning, although one cell recently crossed the Rio Grande near DFX. This storm is surviving despite weak inhibition, and has a threat of all modes of severe as long as it can persist. Uncertainty persists with regard to the extent of convection across the region. However, it appears that severe convection will remain possible through the entirety of the valid WW period as the region remains under the grazing influence of ascent from a mid-level wave over New Mexico/northern Mexico. It is also possible that convection moving eastward from Terrell County may interact favorably with the warm frontal zone near that region and pose a severe threat as well. PFCs/profiles remain supportive of organized convection favoring all modes of severe - thus the severe threat across WW 49 continues. ..Cook.. 04/13/201Mesoscale Discussion 0314
NWS Storm Prediction Center Norman OK 0435 AM CDT Sat Apr 13 2019 Areas affected...west-central into north-central Texas Concerning...Severe Thunderstorm Watch 48... Valid 130935Z - 131030Z The severe weather threat for Severe Thunderstorm Watch 48 continues. SUMMARY...The severe threat continues across WW 48 downstream of a complex of storms between San Angelo and Midland, TX. Additional elevated convection may also pose a hail threat this morning. DISCUSSION...The severe threat continues across WW 48. Convection has congealed into a mix of linear and cellular modes in west Texas, with one lone supercell continuing to exhibit occasionally strong velocity signatures and indications of 1-2" diameter hail potential in Irion County. There storms are slightly elevated and just north of the warm frontal zone, which is probably mitigating any tornado threat. Downstream of this activity, convection continues to deepen within a steep-lapse-rate environment, with effective shear supporting organization and updraft rotation. These storms could also produce occasional 1" hailstones at times as they mature. Over time, high-resolution guidance suggests that the current linear complex and cells out ahead will continue to migrate east-northeast, with hail being the primary severe risk. A new WW may be needed downstream of the current one pending 1) severity of the ongoing MCS and cells out ahead and 2) northward progress of the warm front on the southern periphery of the watch, which may increase the tornado/damaging-wind threat with storms that can become surface based. A new MD will probably be issued to update on downstream watch potential later this morning. ..Cook.. 04/13/2019
Current Convective Watches
URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 49
NWS Storm Prediction Center Norman OK
150 AM CDT Sat Apr 13 2019
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
Southwest and south-central Texas
* Effective this Saturday morning from 150 AM until 900 AM CDT.
* Primary threats include...
A couple tornadoes possible
Scattered large hail and isolated very large hail events to 3
inches in diameter possible
Scattered damaging wind gusts to 70 mph possible
SUMMARY...A gradual increase in convection has been noted across the
area in an environment conditionally favorable for supercells and
tornado potential, along and south of a warm front. The threat
should increase through early/mid morning as lift and moisture each
strengthen.
The tornado watch area is approximately along and 80 statute miles
either side of a line from 60 miles northwest of Del Rio TX to 45
miles north northeast of Hondo TX. For a complete depiction of the
watch see the associated watch outline update (WOUS64 KWNS WOU9).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
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.
&&
OTHER WATCH INFORMATION.
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 48
NWS Storm Prediction Center Norman OK
130 AM CDT Sat Apr 13 2019
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
West-central and southwest Texas
* Effective this Saturday morning from 130 AM until 900 AM CDT.
* Primary threats include...
Scattered large hail and isolated very large hail events to 2
inches in diameter possible
Isolated damaging wind gusts to 70 mph possible
SUMMARY...Thunderstorms should increase in coverage and intensity
across the area through the remainder of the pre-dawn hours, as both
moisture and lift strengthen near a surface low and north of a warm
front. Hail is the main threat, though sporadic damaging gusts may
penetrate to the surface.
The severe thunderstorm watch area is approximately along and 60
statute miles north and south of a line from 55 miles southwest of
Midland TX to 15 miles north of Brownwood TX. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU8).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for 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. Severe thunderstorms can and occasionally do produce
tornadoes.
Apr 13, 2019 0600 UTC Day 1 Convective Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Sat Apr 13 2019 Valid 131200Z - 141200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF FAR EAST TEXAS...LOUISIANA...FAR SOUTHEAST ARKANSAS AND WEST-CENTRAL MISSISSIPPI... ...SUMMARY... Numerous severe thunderstorms capable of producing tornadoes, wind damage and large hail, are expected across parts of east Texas, Louisiana, southern Arkansas, Mississippi, western Alabama and surrounding areas today and tonight. ...East Texas/Louisiana/Southern Arkansas/Mississippi/Western Alabama... A vigorous upper-level trough will move across the southern Plains today as a mid-level jet rounds the base of the system. At the surface, a low will move into the Arklatex with a moist airmass in place to the southeast of the low across east Texas, Louisiana and western Mississippi. Surface dewpoints in the moist sector should be in the upper 60s and lower 70s F by late morning. Thunderstorms should be ongoing across north-central into northeast Texas at the start of the period. This convection with a hail threat, is likely to move into the Arklatex by midday. Further south across southeast Texas into Louisiana, the airmass should become moderately unstable and remain primarily undisturbed. In response to the approach of the upper-level trough, a low-level jet is forecast to move into far eastern Texas and western Louisiana during the early afternoon. Thunderstorms should initiate to the northwest of the low-level jet on the northern edge of the stronger instability. Strong deep-layer shear profiles will favor supercell development. Supercells will have a potential for large hail in the early afternoon. The more dominant storms could produce 2-inch diameter hailstones. As the upper-level trough approaches and the exit region of a progressive mid-level jet moves into southeast Texas during the early afternoon, surface-based thunderstorms should rapidly initiate and move eastward into western Louisiana. RAP forecast soundings across the moist sector at 21Z from Monroe, LA southward to Alexandria, LA show MLCAPE values in the 2000 to 2500 J/kg range. Deep-layer shear is forecast to steadily increase due the approach of the mid-level jet with forecast soundings showing 0-6 km shear of 50 to 60 kt by late afternoon. This combined with strong low-level shear will be favorable for supercells and tornadoes across the moderate risk area. 0-3 km storm-relative helicities are forecast to be in the 350 to 450 m2/s2 range supporting strong tornadoes with the more dominant supercells near the axis of the low-level jet. A potential for long-track tornadoes will be possible and a regional outbreak of tornadoes could occur across parts of the moderate risk area. By early evening, the cluster of severe storms is forecast to move into southwestern and central Mississippi where a potential for strong tornadoes will continue. However, the wind-damage threat may become the more dominant hazard as the convection moves further to the east where instability is forecast to be weaker. ...Northern South Carolina/Central and Eastern North Carolina/Far Southeast Virginia... Southwest mid-level flow will be in place across the East Coast today. At the surface, a moist airmass will exist across the Atlantic Coastal plains where dewpoints should be in the upper 60s and lower 70s F. As surface temperatures warm across the moist airmass, pockets of moderate instability may develop from northern South Carolina northeastward into eastern North Carolina. Thunderstorms are forecast to initiate in the foothills of the Appalachians and move eastward into the stronger instability during the afternoon. SBCAPE values around 1000 J/kg evident on RAP forecast soundings, along with 30 to 40 kt of 0-6 km shear should be enough for a marginal severe threat. Strong wind gusts and hail will the primary threats. ..Broyles/Bentley.. 04/13/2019
dimanche 7 avril 2019
Apr 7, 2019 1630 UTC Day 1 Convective Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1113 AM CDT Sun Apr 07 2019 Valid 071630Z - 081200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PARTS OF SOUTHEAST TEXAS AND WESTERN/CENTRAL LOUISIANA... ...SUMMARY... Damaging winds and hail will be possible through this evening from southeast Texas northeastward to parts of the Tennessee Valley. ...TX/LA... A large and increasingly organized linear MCS is tracking along the middle TX Gulf coast. This system is expected to move across southeast TX and into much of LA through early evening. So far, forward speed of the system has been modest (30-35kt). However, rather strong mid-level flow into the back of the MCS and favorable low-level moisture/instability ahead of the system may aid in acceleration later today. Damaging winds along the leading edge of the convection are the main concern, so have upgraded to an ENH risk across this area. Isolated QLCS tornadoes are also possible if the system continues to organize/intensify. ...Southern AR into MS/TN/KY... Scattered strong thunderstorms have been occurring along the surface boundary extending from southern AR into parts of TN and KY. The air mass south of the boundary will slowly destabilize this afternoon, with various 12z CAM solutions suggesting a few intense convective clusters capable of hail and damaging wind. Later this evening and tonight, the large MCS over TX may persist and move into northern MS and west TN, posing a risk of damaging winds. Confidence that system will remain severe for that long is not high, but given the generally favorable thermodynamic environment, it is not out of the question. This risk will be re-evaluated in later outlooks. ..Hart/Gleason.. 04/07/2019
Current Convective Watches
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 41
NWS Storm Prediction Center Norman OK
710 AM CDT Sun Apr 7 2019
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Southeast Texas
Coastal Waters
* Effective this Sunday morning and afternoon from 710 AM until
300 PM CDT.
* Primary threats include...
Scattered damaging wind gusts to 70 mph possible
Scattered large hail events to 1.5 inches in diameter possible
A tornado or two possible
SUMMARY...A maturing squall line across south central Texas will
develop east-northeastward through the day, with additional storm
development possible in advance of the line. The storm environment
will favor damaging winds and large hail as the primary threats with
the strongest embedded cells and bowing segments. A tornado or two
will also be possible with circulations embedded in the line, or
with cell interactions immediately in advance of the line.
The severe thunderstorm watch area is approximately along and 90
statute miles north and south of a line from 40 miles west northwest
of Palacios TX to 50 miles east southeast of Huntsville TX. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU1).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for 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. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 40...
AVIATION...A few severe thunderstorms with hail surface and aloft to
1.5 inches. Extreme turbulence and surface wind gusts to 60 knots. A
few cumulonimbi with maximum tops to 550. Mean storm motion vector
26030.
...Thompson
Mesoscale Discussion 277
Mesoscale Discussion 0277NWS Storm Prediction Center Norman OK 1113 AM CDT Sun Apr 07 2019 Areas affected...Southeast TX...Middle/Upper TX Coast Concerning...Severe Thunderstorm Watch 41... Valid 071613Z - 071745Z The severe weather threat for Severe Thunderstorm Watch 41 continues. SUMMARY...Threat for damaging wind gusts, hail, and a tornado or two remains across southeast TX and the middle/upper TX Coast. DISCUSSION...Air mass ahead of the ongoing convective line continue to destabilize amidst continue moisture advection. Dewpoints are now between 70 and 72 deg F areawide and mesoanalysis estimates 2000+ J/kg. Additionally, the overall system is well organized, evidenced by strong (i.e. 3-5 mb) height rises behind the line and sharpening reflectivity gradient along its leading edge. Another factor suggesting intensification is the southeasterly surface winds and resulting increased convergence. Two factors potentially impeding further intensification/organization are the line-parallel orientation of the shear vectors and the slowing of the shortwave trough currently moving through south TX. Overall expectation is for gradual intensification/organization over the next few hours with the forward speed of the overall system to increase. Strong wind gusts are the primary severe threat. Some hail also remains possible. A brief tornado or two is also possible, particularly as the system intensifies and forward motion increases. ..Mosier.. 04/07/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LCH...SHV...HGX...CRP...EWX... LAT...LON 28029674 30239688 31749469 29159468 28029674
samedi 6 avril 2019
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