jaxjagman

Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 308 AM EST Sat Feb 08 2020 Day 3 Valid 12Z Mon Feb 10 2020 - 12Z Tue Feb 11 2020 ...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL EXTENDING FROM LOWER MISSISSIPPI VALLEY ACROSS THE LOWER TENNESSEE VALLEY INTO THE SOUTHERN APPALACHIANS... ...Lower Mississippi Valley across the Lower Tennessee Valley into the Southern Appalachians... Strong short wave energy closes off as it drops across Southern CA to a position off the northern Baja Peninsula by the end of Day 3. Short wave energy ejected from the closed low rides along a slow moving front extending from the Southern Appalachians into the Lower MS Valley, providing synoptic scale ascent for heavy rainfall over areas that received flooding in the recent past. There is a good model agreement with the overall setup, increasing confidence in an enhanced flash flood threat in this area. As the closed mid level low settles just off the Southern CA coast during the second half of Day 3, the west southwest mid level flow becomes increasingly parallel to a slow moving front extending from the Mid Atlantic Coast to the western Gulf of Mexico. Ahead of the boundary, a 45/55 knot low level west southwest flow sends 1.50 inch precipitable water air (which is between two and three standard deviations above the mean) along the front, peaking after 11/00z. Within the moisture plume, model soundings showed 500/1000 J/KG of MUCAPE extending from eastern LA into west central GA. The combination of moisture and instability should be sufficient to support low topped convection along the front. Convection is possible at the beginning of the period across MS ahead of the initial short wave energy, extending into northern AL into the Southern Appalachians during the afternoon. The low topped storms are expected to produce heavy rainfall over areas that saw flooding with the last round of heavy rain earlier in the week. After a possible lull during the evening hours, the next area of convection develops along the front across AR into central MS. During this time, difluence increases over the front in the presence of a dual jet structure extending the Lower MS into New England, which should allow an areal coverage in heavy rain. As the front drops slowly southeast during the late evening and overnight, cells are expected to track from southwest northeast along the front, producing training along the front from central MS into northern GA and upstate SC. Hourly rainfall rates during this time could exceed an inch, especially where training occurs. There is a strong model signal for 2.00/4.00+ inches of rainfall extending along the front, with the highest amounts extending from central AL into far northern LA, closest to the best instability axis. Over the Southern Appalachians into northern AL, three hour flash flood guidance values are as low as 1.00/1.50 inches, as these areas received more than 300 percent of normal rainfall in the past week. There are still rivers in flood here, with soils still nearly saturated. Though rainfall amounts here are lower than further southwest, the impact here could be greater. After collaborating with the WFOs MRX/FFC/GSP, a Moderate Risk was placed here for Day 3. Further southwest, extending from northern Al into central MS, the antecedent conditions are not quite as wet, with the bulk of the heaviest rain with the last event occurring further northeast. However, the model signal here is stronger for 3.00/4.00+ inches of rainfall with the convection, lying closer to the best instability. Based on this, and after collaborating with WFOs BMX/JAN/MEG, the Moderate Risk was extended across northern AL into central MS for Day 3. Hayes

Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 258 PM EST Sun Feb 02 2020 Day 3 Valid 12Z Tue Feb 04 2020 - 12Z Wed Feb 05 2020 ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE LOWER MISSISSIPPI AND TENNESSEE VALLEYS... 21z update... No significant changes to the previously issued Marginal Risk. Any changes were based primarily on model trends in the placement of the axis of maximum rainfall. Model soundings showed that the best instability remains south of KY/TN, with the best MUCAPE values relegated to the Lower MS Valley and central Gulf Coast (which is not unusual for a cool season system). However, model soundings did show some elevated instability across these areas, with MUCAPE values generally less than 100 J/KG. There is some spread on how models distribute the elevated instability, which has some effect on where the heaviest rainfall axis ultimately resides. Moisture is plentiful, with precipitable water values between two and three standard deviations above the mean transported into the upper TN Valley and lower OH Valley, where three hour flash flood guidance values are as low as 1.50 inches. While there is some model spread regarding the highest rainfall amounts, each of them placed the axis west of the lowest flash flood guidance. Based on this, the Marginal Risk was left in place. If there is better agreement concerning the placement of the heaviest rainfall (especially if it impacts areas with lower flash flood guidance values), a Slight Risk could be needed in later forecasts.

Subsurface is almost cool basin wide,no real sign of any sig WWB upcoming tho the CFS does show right now a KW passing east of the IDL which should warm up region 3 past the mid month,if its right

Surface has cooled some since the last update in 3.Towards the end of the month into the first of next it looks possibly another KW will get to 3 again,seems possible just as well the MJO could get into 8 unlike what the RMM'S are showing today killing it off in 7.But either way the signal looks weak

Starting to think you were on to something back into early Dec,Seems possible the cold pool waters will get sfifted eastwards thats into 3.The subsurface is cooling west of the IDL,plus we have an active CCKW starting to get past the IDL which should help upwell the warmer subsurface east of it

Subsurface has warmed somewhat,not much change with the surface,not much left of the cooler subsurface in the east as well.

Yeah i have no doubts there are more EF-4 and probably even more EF5 before hand we just dont know

I see what you are saying,but these were downgraded https://www.weather.gov/ohx/forgottenf5

But this was in Alabama,it's marked on that link i posted above from NOAA

There's only been one confirmed F-5 in Tn since 1950,that was the Lawrenceburg one,now if you want to consider parts of Northern Alabama as parts of the Valley,i'd agree with you.Its really insane tho if you look at North Alabama per capita how many F-5'S they had,that's just crazy https://www.spc.noaa.gov/faq/tornado/f5torns.html

I didnt word that right,it was after about 45 min to an hr the convection started after the squall passed.I went back and looked at the K-Index on all the models there shouldn't have beeen much of any post convection,its still lightning and thunder here

Convection of this system seemed to lag behind the main line.We've had thunder now for almost 45 min recently after that main squall passed,every model did a poor job with the mesoscales in our parts

Only been one EF-5,Lawrenceburg

Tornado on the ground in Arkansas,looks to be headed towards Lamar

Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1126 AM CST Fri Jan 10 2020 Valid 111200Z - 121200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR MISSISSIPPI...ALABAMA...PARTS OF WESTERN TENNESSEE...SOUTHEAST LOUISIANA...AND THE WESTERN FLORIDA PANHANDLE... ...SUMMARY... Severe thunderstorms capable of damaging winds and tornadoes are expected across parts of the southeastern U.S. on Saturday. A risk for damaging wind gusts will include parts of the Ohio Valley and Mid-Atlantic states. ...Synopsis... An intense mid-level shortwave trough will rapidly move from the southern Great Plains to the Lower Great Lakes late Saturday night. In the low levels, a surface low initially over east-central AR will develop northeast towards central IN by early evening and subsequently to the NY Adirondacks by Sunday morning. A warm front will advance northward into parts of the OH Valley and Mid-Atlantic states while a cold front sweeps east across the central Gulf Coast and OH Valley. ...TN/MS/LA/AL/GA/FL Panhandle... A squall line with a risk for severe gusts will be ongoing Saturday morning from near the OH/MS River confluence south-southwestward into coastal LA and the west-central Gulf of Mexico. Intense wind fields associated with a 100-kt 500mb jet and an 80-kt southerly LLJ will gradually shift east/northeastward during the period in association with the progression of the mid-level trough. Strong low-level mass response and associated advection processes will support the poleward transport of lower 60s degrees F dewpoints into middle TN and upper 60s farther south near I-20. Intense background flow fields and associated very large hodographs will support both the threat for severe gusts with bowing segments in the squall line and a conditional risk for tornadoes with any supercell managing to develop ahead of the squall line or with stronger mesovortices. The risk for significant severe gusts will likely focus with more pronounced bowing segments and longer-lived mesovortices. As the squall line advances across AL into GA late in the day, models are indicating less organization in the line as it encounters slightly weaker instability concurrent with the upper system becoming increasingly displaced from the GA/north FL vicinity. ...OH Valley... The northern periphery of the severe risk (damaging gusts and perhaps a brief tornado) will likely extend into the OH Valley associated with the northern part of the squall line expected to develop Friday night into Saturday morning. Intense wind fields coupled with a few hundred J/kg MUCAPE would seemingly support a conditional risk for damaging gusts with a fragmented convective band as far north as OH to the southeast of the forecast surface low track. ...Carolinas north into VA/MD... The latest model guidance shows at least weak instability (MUCAPE ranging from 250 J/kg north to 1000 J/kg south) as flow strengthens during the evening into the overnight. CAM guidance suggests the possibility for a re-invigoration of storms east of the Appalachians as low-middle 60s surface dewpoints infiltrate the Carolina/VA Piedmont. Damaging gusts appear to be the primary risk with this activity during the 04-12z period. ...MAXIMUM RISK BY HAZARD... Tornado: 10% SIG - Enhanced Wind: 30% SIG - Enhanced Hail: 5% - Marginal ..Smith.. 01/10/2020

Short range models are showing alot more instability.Memphis got bumped up from a slight to moderate risk. Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0652 AM CST Fri Jan 10 2020 Valid 101300Z - 111200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS NORTHEAST TX...SOUTHEAST OK...NORTHERN LA...CENTRAL/SOUTHERN AR... ...SUMMARY... Widespread severe thunderstorms are likely across the southern Great Plains, mainly this afternoon and evening, spreading east into the Lower Mississippi Valley tonight. The most dangerous corridor for strong tornadoes and intense damaging winds should be centered on northeast Texas through northern Louisiana and southern Arkansas this evening through the overnight. ...South-Central States... An outbreak of severe thunderstorms is possible later today through tonight, with the most dangerous portion being tonight into early Saturday morning with a potential derecho and embedded strong tornado risk. Primary changes this outlook are to expand the Moderate Risk east across the Lower MS Valley and increase tornado probabilities for the evening/overnight period. Vigorous shortwave trough near the AZ/NM border will shift east across the southern Great Plains through 12Z Saturday. A powerful 90+ kt jet at 500 mb is expected to emanate out of the base of the trough across east TX/OK. In response to this trough, the LLJ will increase throughout the period, more notably late in the period. Along the northwest periphery of low-level moisture advancement, multiple elevated supercells are expected to develop this morning across parts of western/northern OK into southern KS. A large hail risk is anticipated initially, but convection will have an opportunity to become surface based towards midday, though discrete cells should not be particularly common as a polar front sags into this region. Farther south, strong boundary-layer heating is expected across west TX where 0-3 km lapse rates are forecast to approach 9 C/km. At the same time, strong mid-level height falls will spread across the Pacific cold front/dryline by peak heating, and thunderstorms should easily develop along the eastern edge of this steeper lapse-rate plume. Scattered supercells will evolve from east-central OK to north-central TX by 19-21Z, and farther south into south-central TX during the late afternoon. This activity will be strongly sheared and could produce very large hail early in the convective cycle. With time, multi-scale forcing will encourage consolidation into an extensive QLCS that should accelerate toward the Ark-La-Tex region during the evening. Damaging winds will likely be common along the QLCS with embedded mesovortex and supercell tornadoes. Guidance such as the 00Z HRW-NSSL and HRW-ARW, along with the 06Z NAM and 11Z HRRR suggest that pre-frontal convection should develop out ahead of the QLCS across the Sabine Valley towards 06Z. As this convection spreads northeast across northern LA towards the Ark-La-Miss, the strong tornado potential should increase amid strengthening 0-1 km SRH of 300+ m2/s2 and upper 60s surface dew points. A couple long-track tornadoes are possible given fast storm motions but convective mode should be messy. Consolidation with the accelerating upstream QLCS should eventually occur, sustaining potential for widespread damaging winds with embedded significant severe gusts and tornadoes as it spreads toward the Lower MS Valley through 12Z. ..Grams/Mosier.. 01/10/2020

Loooking like it could be an active tropical season with possibly a LaNina brewing into summer

Even without mesocyclones the wind dmg. could be intense as the gradient tightens,if its right of course

Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0359 AM CST Tue Jan 07 2020 Valid 101200Z - 151200Z ...DISCUSSION... A multi-day severe weather episode is expected Day 4-5/Fri-Sat from the Arklatex into the Deep South vicinity. An intense mid/upper trough over the Four Corners and northwest Mexico early on Friday will eject eastward into the southern Plains by 12z Saturday. At the surface, low pressure will develop over TX and shift east/northeast toward central AR by 12z Saturday. Ahead of the low, rich Gulf moisture will stream northward across eastern TX/OK and expand eastward across the lower MS Valley and Gulf Coast states through Saturday. 60s F dewpoints are forecast to extend as far north as the lower OH Valley by Saturday morning, with upper 60s to near 70s dewpoints over parts of the Arklatex on Friday into much of LA/MS/AL/GA on Saturday. This anomalously rich and broad warm sector will reside beneath a 50-70 kt southerly low level jet and 80+ kt southwesterly 500 mb jet streak. While some questions remain over how pristine the warm sector ahead of the surface low and cold front will remain, especially on Saturday, this kinematic and thermodynamic parameter-space will support severe thunderstorms capable of all severe hazards from the Arklatex into the TN Valley/Gulf Coast states Friday and Saturday. Mixed convective modes are anticipated given the strength of shear, with a QLCS likely developing ahead of the surface cold front. This will support damaging gusts and mesovortex tornado potential. Additionally, any semi-discrete convection that develops ahead of the QLCS will be in an environment capable of supporting supercells and tornadoes, especially from east TX through central MS/AL. Beyond Saturday, a reprieve from severe potential is expected on Day 6/Sun as high pressure builds over the east and the surface cold front stalls near the southeast Atlantic coast and northern Gulf coast. However, some severe potential could return early next week as a mean trough is forecast to persist across the western half of the country while shortwave impulses eject east/northeast from the southern Plains through the Midwest on Day 7-8/Mon-Tue. Confidence in how much the airmass will be able to recover and destabilize remains in question, as the southeastern U.S. is forecast to receive quite a bit of rain. As such, confidence is too low to include severe probs at this time. ..Leitman.. 01/07/2020

Looks like a flood potential is going to be real.Pattern reminds me of last year when we see these lows develop to our SW and track right through TN.

Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0357 AM CST Mon Jan 06 2020 Valid 091200Z - 141200Z ...DISCUSSION... A multi-day severe weather episode is expected across portions of the Arklatex into the Deep South vicinity on D5/Fri and D6/Sat. The ingredients for severe thunderstorms will being to fall into place Day 4/Thu as an upper ridge spreads eastward across the eastern U.S. and a large-scale trough intensifies across the western states. At the surface, a strong surface pressure gradient will develop from the Midwest to the western Gulf Coast, allowing rich Gulf moisture to begin streaming northward across east TX and the lower MS Valley vicinity on Thursday. The warm sector will expand through the day on Friday from eastern OK/TX eastward across much of the TN Valley and Gulf Coast states. Surface dewpoints are expected to be impressive for this time of year, climbing into the mid 60s to low 70s as a deepening surface low shifts eastward across OK/TX on Friday. This will occur as the western trough ejects eastward into the southern Plains and an intense southerly low level jet overspreads the region. Forecast guidance also shows a weak EML emanating from the Mexican Plateau spreading over parts of the region, providing a weak cap that should limit warm sector convection initially. Confidence has increased that a strong vertical shear parameter-space will overlay a high-quality warm sector ahead of the ejecting trough and a southeastward-advancing cold front Friday afternoon through Friday night. As such, a 30% severe delineation has been included for parts of the Arklatex within the broader 15% severe probability area. On Day 6/Sat, severe thunderstorm potential is expected to continue into portions of the TN Valley and the northern Gulf Coast vicinity. Similar to Friday, intense shear parameters and adequate instability will exist across the region as the upper trough becomes more compact and lifts northeast across the mid/lower MS Valley to the OH Valley. 15% severe probabilities will be maintained at this time as questions remain with respect to how pristine the warm sector will remain over MS/AL and vicinity, as well as timing/location of key surface features. That being said, the overall pattern will support severe thunderstorms into Saturday evening across much of the Deep South vicinity. Confidence in severe potential beyond Day 6/Sat is low, though guidance suggests stormy conditions could return to parts of the Southeast on Monday/Monday night. ..Leitman.. 01/06/2020

It's still cool into the subsurface into region 3,that's not going to go away anytime soon

ONI is back into a Nino last update,so we'll see in a couple months 2018 -0.9 -0.8 -0.6 -0.4 -0.1 0.1 0.1 0.2 0.4 0.7 0.9 0.8 2019 0.8 0.8 0.8 0.7 0.6 0.5 0.3 0.1 0.1 0.3 0.5

Right now the Euro shows a warm front lifting northward next weekend.As the WF lifts you should anyways see even a chance of the thunderstorms possibly severe into next weekend As the LLJ starts to strenghten more or less this drives up the Thetea-E along with SB Capes with DP'S getting into the lower 60's,impressive for Jan.With convection some of those totals might be much higher..IMO