jojo762

Hurricane Maria Discussion Number 14 NWS National Hurricane Center Miami FL AL152017 1100 AM AST Tue Sep 19 2017 Reports from an Air Force Reserve Hurricane Hunter Aircraft indicate that Maria regained category 5 status shortly after the last advisory, and that it is currently maintaining an intensity near 140 kt with a central pressure near 927 mb. The aircraft data suggests an outer wind maximum that could be the start of an eyewall replacement cycle, but this feature does not yet have a good signature in radar data or microwave imagery. The eye of Maria has been wobbling quite a bit, but a smoother long-term motion is 300/9. There is little change to the track forecast reasoning or the forecast track since the previous advisory. A weak ridge situated over the western Atlantic is expected to steer Maria west-northwestward through 48 hours, and on this track the center of the hurricane is forecast to pass near or over the Virgin Islands and Puerto Rico on Wednesday. After that time, the western portion of the ridge is forecast to weaken, partially due to the influence of the large circulation of Hurricane Jose off the U.S. east coast. This pattern should cause Maria to turn northwestward and then north-northwestward by days 4-5. The track guidance is tightly clustered through 72 h and fairly well clustered at 120 h, and the new track is to the left of center of the cluster mainly between the GFS and ECMWF models. Maria should remain in a generally favorable environment through 48 h, and based on this and the latest guidance the new intensity forecast keeps Maria at 135-140 kt up to the time of landfall in Puerto Rico. After crossing Puerto Rico, the upper-level winds are expected to become less favorable, and the intensity forecast shows a slow weakening that follows the upper edge of the guidance. A complication to the intensity forecast is that there will likely be fluctuations caused by eyewall replacement cycles superimposed on top of the general trends shown in the official forecast. KEY MESSAGES: 1. Maria will continue to affect portions of the Leeward Islands today and the core of the hurricane is expected to move near or over Puerto Rico and the Virgin Islands tonight and Wednesday. Everyone in these areas should follow advice from local officials to avoid life-threatening flooding from storm surge and rainfall. 2. Wind speeds atop and on the windward sides of hills and mountains and on high-rise buildings could be much stronger than the near- surface winds indicated in this advisory. FORECAST POSITIONS AND MAX WINDS INIT 19/1500Z 16.3N 63.1W 140 KT 160 MPH 12H 20/0000Z 17.0N 64.1W 140 KT 160 MPH 24H 20/1200Z 18.0N 65.7W 135 KT 155 MPH 36H 21/0000Z 18.8N 67.1W 125 KT 145 MPH 48H 21/1200Z 19.6N 68.4W 125 KT 145 MPH 72H 22/1200Z 21.5N 70.5W 120 KT 140 MPH 96H 23/1200Z 24.5N 72.0W 105 KT 120 MPH 120H 24/1200Z 27.5N 72.5W 95 KT 110 MPH

Something that seems to be being understated is the impact to the USVI and BVI with the current forecast track. They got wrecked by Irma, and holy hell there are about to take it just as bad if not worse as they are going to be in the RFQ of Maria.

Also shows it restrengthening as it makes its loop back to the west. LOL. GFS seems much more believeable than the euro with its handling of Jose at this point imo.

High pressure across the MW/NE, Jose just east of due north of Maria, an upper level low over the northern gulf coast, and a weak high to the east of Maria. Geesh...

So, you're just going to ignore a dropsonde then that measured 140mph at the surface and 160+mph just above the surface?

Well looking like our final legit chances in the central plains could be taking shape next week possibly into next weekend, still some timing differences between the euro/GFS, but appears there will be several opportunities for severe storms for at least the northern plains, but probably extending into the central plains on a couple days as well. EML is progged to be quite strong so that will play a big role in how things evolve, but prospects look fairly good with an unseasonably strong mid-level trough ejecting into the N/C Plains. After this period remains a bit uncertain ATTM... But currently leaning toward the inevitable, and dreaded, death ridge developing by ~June 20, likely ending any legit severe/tornado prospects for the central/southern plains for quite some time.

13 tornado reports during one of the most active periods of the year, typically. Only two of which were in the plains... eek.

Some hint from the GFS/GEFS that things could heat up a lot more somewhere cross the plains toward mid-month with appreciable SW flow and abundant moisture... so hopefully that pans out. Not quite in EC or EPS range yet.

This is somewhat reminiscent to 2013 imo as well, especially by Friday/Saturday, H5 map isn't exactly the same but has some similarities, notable differences being the presence of a large NE-trough this go around and the central CONUS trough isn't quite as strong, but other features are similar... Thursday looks mildly interesting, but thinking capping will hinder convective development, and therefore any potential it may have, as of now. GFS has trended with a weaker cap on Friday/saturday, so naturally given the progged thermo/kinematic profile, along with only subtle forcing, those days would both probably be fairly interesting if things were to evolve as shown now (doubtful)... We've all seen what these extreme instability/moderate shear environments have been capable of in the past...

I like our chances of seeing at least SOMETHING the end of this week/weekend... At least one day could be fairly impressive, depending on how a myriad of environmental factors evolve. CIPS GEFS analog percentage for Day 6-8 of at least 10 SVR reports. GFS for several runs has been moderately impressive -- to varying degrees, for a variety of reasons -- for Friday specifically, but Thursday and Saturday could feature severe storms as well. A bit too far out to determine potential hazards really, but the wind profile will be quite favorable for supercells with impressive veering with height.

OUN highlighting how models are starting to converge on at least modest, but potentially somewhat strong, W/SW flow atop moist/unstable environment for multi-day severe threat.

Somebody should go ahead and make a thread for this coming week 5/15-20/21 as it looks like we will have several days with severe possibilities with perhaps a big/interesting day or two mixed in. Tuesday continues to look like a highly volatile day, moisture is perhaps a little less than I would want (still mid/upr 60s DPs per GFS along the DL, a little less on previous euro runs though), but moderate/strong instability juxtaposed to a somewhat favorably timed strong mid-level jet streak coinciding with a strong LLJ of 35-50kts by 00z, could be quite a day.

Both the 00z Euro and 12Z GFS operational runs are in fairly good agreement on a fairly substantial threat developing along and east of the dryline across Western/Central KS and Western OK on Tuesday afternoon and evening with an impressive 35-50kt LLJ by 00Z and a 50-60kt mid-level jet penetrating the strongly unstable warm sector by 00Z... Both models, as you can imagine, show an impressive parameters space along with isolated, discrete convection by 21-00Z. Main difference between the two would appear to be the Euro showing VBV above 500mb, and the GFS showing no VBV. Don't have too much time to delve into any other details, perhaps someone else could add something more... Capping appears to possibly be an issue...

I have Monday-Friday off next week as well, still have some finals on Tuesday and Thursday but those are all in the morning. Looking like an active period, with several impressive days (at least it appears there will be). Surprised by the lack of talk about it.

Also, 12Z op-Euro shows what would appear to be a fairly substantial threat next Tuesday evening across KS/OK, GFS does as well but there is still some disagreement in timing of the S/W and location the better threat area.

Certainly... Most of the 00Z models I have seen thus far are indicating a fairly substantial parameter space developing, though spatially limited, across E TX PH and into W/SW OK... main question would be convective initiation, given the expected strength of the cap... Nonethless most models show convective inhibition weakening sufficiently by 21-00Z for CI to occur along the DL (perhaps a DL bulge near the jet max will increase low-level convergence and will further aid in CI)... however the 12NAM/3NAM/GFS are all fairly sparse, and short-lived, with convection along the dry line by late afternoon/early evening. Tricky forecast. Any discrete supercells within that parameter-space "sweet spot" would have a good shot at tornadoes, and perhaps a strong tornado, given impressive PBL moisture --> low-LCLs, ~200m2/s2 0-1KM SRH, impressive instability (especially low-level 0-3KM CAPE, nearing 150J/KG per 00Z GFS), and strong cloud-layer shear of 60-75kts. If CAMs continue to zone in on this particular area, wouldn't be surprised to see a 10% hatched TOR by the 1630 or 20Z D1SWO updates.

SPC added a 10% TOR and 30% hatched hail area to SE NM/W TX... kiss of death to the setup.

Yeah that weakness in low-level flow above 850mb is really dampening this from looking much better, quite disappointing given that we actually have an appreciable LLJ with moderate instability and impressive moisture by 00Z... Regardless, as you said, its mid-may now so really anything could happen, wouldn't be surprised to see a few tornadic supercells, but also wouldn't be surprised if we just got clusters and very large hail-producing non-tornadic supercells. Thursday, however, could be more interesting... across north Texas and perhaps the arklatex.

Wednesday (5/10) continues to look more and more interesting on the models. 12Z EC depicts a classic 500mb jet timing, and shows a 30-35kt LLJ developing by 00Z across western OK/TX PH and into southern KS, with moderate instability. Potential for morning convection throws some uncertainty into the mix, and VBV wind profiles also throw a wrench into what the dominant storm-mode will be. Thinking a mixed storm-mode of supercells and clusters seems probable, with all severe hazards possible. Tid Bit from DDC AFD:

**Takes peek at long-range in 00z GFS** Oh my god... It's over 10-days out, so it's frivolous to get into much detail, as the details are obviously nebulous, but needless to say I would NOT be upset if that happened. FWIW, op-GFS has been consistent in showing significant troughing across the plains sometime in the May 17-22 time frame, GEFS/EPS are also consistent in showing mean western troughing leading up to this time-frame, with many GEFS members -- to varying degrees -- showing a significant trough.

I get the feeling we might be able to get some Panhandle magic this coming week. The more SSW orientation of the mid-level flow makes it a little less certain to me though. Not looking like we'll see any "big" days at this point... but severe storms with large hail and damaging winds are still likely on a couple/few days next week across the plains.

Man... Crazy to see the region THIS drought-free. I remember 4-5 years ago when it seemed like the entire plains was covered in extreme drought.

While it is a while out, and a lot will likely change... both the euro and GFS operational runs currently indicate that the cut-off low progged to be over the four-corners region could eject into the plains sometime in the May 11-13 timeframe as a negatively tilted trough... so that's something. Ensembles have been trending toward this type of idea as well. Lots of variables at play and more questions than answers given how far it is out, but this would appear to be our next best shot at meaningful severe potential... enjoy the beautiful weather this coming 7-10 days folks!

I'm amped. On the bright side we'll be getting some pretty nice weather. Grass and weeds are going to grow at ungodly rates because of all the recent rainfall and succeeding sunshine... ):

Looking ahead some... Appears that the next best shot at a trough ejecting into the plains will be in the May 6-11 time frame... EPS/GEFS/GEPS generally agree on showing mean western troughing during this time. Perhaps the more important thing to pay attention to is the evolution of the high-pressure that is progged to develop over the Central/Southern Plains shortly after the current wave(s) kicks out east, as this will have a large impact on what actually happens to any potential troughs and S/Ws.