andyhb

For now all I will say on that is a warm sector as extensive (with quality BL moisture) as is being progged by the GFS and Euro for Saturday generally yields problems in the cold season. A lot of details to be sorted out surrounding the influence of the strong SE ridge and the trough's ejection though.

12z Euro was showing a fairly significant severe weather setup (first of the year if it comes into fruition) over the Red River Valley eastward into the Arklatex on Tuesday.

Multiple reports of damage trickling out of that area now.

Sound analysis as usual.

2013-14 say hi.

I wasn't necessarily judging it just from the perspective of chasing though.

Well that's quite the tone to come back to this site with. 10/15 of the EF3+ tornadoes occurred before April last year. EF3+ tornadoes occur when the setups are most favorable for classic supercells most of the time, regardless of biases in terms of buildings to hit/etc. Was 2011 a great chase season? No, but that was mainly because the setups were in unfavorable locations. 2017 had a number of Plains "potential events" that underperformed or just were generally not that great in terms of photo/video opportunities. Removing the subjectivity of ratings, 6/12 was basically the only above average chase day during the AMJ period last year.

Cosigned.

Well it's about that time of year again with just over two months until meteorological spring begins. Closest to first high risk date last year -> Stebo: March 13th (actual: January 22nd) Closest to number of tornadoes last year -> lookingnorth and hurricaneman: 1300-1400 (actual: 1359 as per December 27th) As mentioned in the previous thread, last year was one with a generous amount of tornadoes overall, yet very few intense (EF3+) tornadoes, yielding a very strong contrast between overall numbers and "quality" of events. There were four high risks that generally underperformed due to various factors, one being the hangover sub-tropical influence from the 2015-16 super Nino, despite the presence of weak La Nina SSTAs in the tropical Pacific. Looking forward to the coming year, it appears we'll have lingering La Nina influence in place once again, but this time with a less prominent sub-tropical jet. The analogs presented below in Anthony Masiello's tweet represent years with a good QBO/ENSO match to the current winter. As one can see, the current December regime is a close match to the December 250 mb geopotential height anomalies, although a sample size of just three winters is not ideal. Other years that have been mentioned in analogs from various winter forecasts include 1954-55, 1995-96, 2005-06, 2007-08 and 2013-14 (I've seen some other bigger years thrown around, although they don't appear to be as good matches to the SSTA patterns, QBO structure, etc). We've also seen a dominant East Siberia/Sea of Okhotsk standing wave vortex as of late, whose downstream effects have generally encouraged a persistent -EPO via wavebreaking (something that hopefully eases a bit later in the season). The southeast ridge has also been fairly suppressed. The PDO has also fallen into a more neutral state lately, as opposed to the positive conditions of the past few years, which is at least somewhat promising. We also currently have a -TNI in place with cooler SSTAs in Nino 1+2 vs. Nino 4, and a positive state has shown some correlation to increased chances for larger outbreaks. The PDO and weakened sub tropical jet appear to be two factors favouring an uptick in activity vs. the mean of the past 5 or so years. It remains to be seen how much La Nina will influence the upcoming late winter and spring (MEI has been relatively weak), although I'd tend to lean towards at least cold neutral forcing come peak season. Number of tornadoes: 1225 First High Risk: March 16th

D3 ENH, partially hatched for N TX and a good chunk of OK. Given the forcing near the cold front and it's rather fast motion, convection will almost certainly be linear/undercut with time in that area (damaging winds, etc.). I'm a bit curious to see if we can get a few discrete cells popping out ahead given the degree of forecast low level shear and considerable BL moisture content (into the upper percentile for this time of year in this area) across guidance. This prospect would be more likely in a case where a more well developed secondary surface low can develop along the low pressure trough extending southward from the primary low over the Prairies, which would then amplify low level convergence/surface backing ahead of the front. Such a low is spurned on by the southern in a pair of vorticity maxima that emerges from the Four Corners region through the morning and afternoon Saturday. There is also a bit of a coupled upper jet structure overhead enhancing divergence aloft, which would also imply increased large scale ascent ahead of the front.

Pretty strongly worded AFD coming out of DDC with regards to tomorrow's severe threat.

Wedge tornado reported N of Scott City per SN moving NE.

70-80 kts of effective shear and 400-500+ m2/s2 ESRH for that storm SW of Leoti to work with.

MCD out for an imminent tornado watch in the High Plains. Mesoscale Discussion 1678 NWS Storm Prediction Center Norman OK 0239 PM CDT Sun Oct 01 2017 Areas affected...Central High Plains Concerning...Severe potential...Tornado Watch likely Valid 011939Z - 012045Z Probability of Watch Issuance...95 percent SUMMARY...Severe threat is increasing across the central High Plains. Tornado Watch is warranted for this region and will likely be issued by 2030z. DISCUSSION...Large-scale forcing for ascent is spreading across the central Rockies with high-based convection increasing across the northern CO Rockies into the High Plains where boundary-layer moisture is somewhat limited at the time. This activity is expected to mature over the next few hours as it encounters increasingly moist air mass from extreme northeast CO into southwest NE. Bow-type structures may ultimately evolve from this activity as it propagates northeast along a boundary draped across this region. Farther south, strong boundary-layer heating has contributed to a substantial dry line surge into northwest KS. CU field is increasing in areal coverage both west and east of the dry line, indicative of convective temperatures being breached. It appears thunderstorms will evolve across northwest KS over the next few hours and shear/instability favor discrete supercells. Latest HRRR model guidance supports this idea with two distinct scenarios evolving this evening. While storm mode may favor wind/hail with activity spreading across northeast CO into southwest NE, higher moisture/instability across northwest KS into south-central NE suggests a few tornadoes may evolve from supercells across this region. Tornado watch will likely be issued within the hour to account for this threat. ..Darrow/Guyer.. 10/01/2017

Also, couple of potentially tornadic supercells W of the ABQ metro right now.

Could be a window for a nice sup or two in the central High Plains (specifically NW KS and SW NE) late tomorrow afternoon/evening. Strong flow aloft and good veering in the lowest 3 km will make for favorable shear profiles, although moisture may be a bit on the marginal side for tornadic potential especially if mixing is more than forecast. There is a fairly strong signal amongst the CAMs for supercell development and modest upsloping associated with the backed low level flow near the lee cyclone should allow for it along with moderate large scale forcing for ascent.

If the Key West radar was positioned further east, it likely would've had more problems.

For reference, that's the first NWS radar completely destroyed since Andrew took out the Miami one. A downburst did crumple the radome of KDRT back in 2001, but the internal components were not exposed.

San Juan radar completely destroyed.

Josh is back online.

That area of 115+ kt velocities aloft on the radar is huge now...

Considering we basically know nothing of what's happened in Dominica (and what we do know sounds pretty bad), I'd temper your gusto a bit.

Note that 139 kt SFMR was from the SW eyewall, i.e. one of the weaker quadrants in a NW-moving TC.

Hmm, that microwave look isn't one that is totally consistent with a sub 920 mb storm.

Unsurprisingly the situation is critical in Dominica early this morning.