Severe weather risk 4/30 - 5/3

[Radtechwxman]

58 minutes ago, bjc0303 said:

A slowing trend would actually be beneficial...

Well if it slows anymore you will have it time Wed night. You would need it to slow a lot to time on Thurs at a favorable time. So yea not hoping for slowing

[andyhb]

3 hours ago, OUGrad05 said:

30% is surprising on a D6 IMO, especially with some many small details yet to be ironed out.  I like what I'm seeing at this point for possibilities and am desperate for a chase.  Euro is more bullish than GFS so there's that.

2 hours ago, StormChaser4Life said:

Yea I'm not sure why SPC went 30% this far out esp given the uncertainty. Really starting to fear the ill timed waves on models. Would be disheartening to see three days of nothing good to chase. Still got several days....hope it will change but unfortunately a slowing trend makes more sense

SPC is not forecasting for your chasing needs.

[OUGrad05]

15 minutes ago, andyhb said:

SPC is not forecasting for your chasing needs.

Ya think

[nrgjeff]

2 hours ago, CheeselandSkies said:

Yes but it's also technically as high as they can go beyond Day 3, so IMO it should carry the implication of something higher end (>30% ENH by the time DY1 rolls around). Was a time when if they went MDT on DY2, you knew all **** was going to break loose.

 

2 hours ago, nrgjeff said:

SPC 30% is justified based on broad pattern recognition. Plus the ECMWF still has a robust look. All models are pretty consistent for a week out. Remember 30% is just Enhanced, still Slight in Old School, nothing crazy. We will have excellent turning with height up to 700 mb. Speed shear will be robust all the way up. Moisture is not a question Wednesday. When a shortwave ejects within southwest flow in early May.. Look for fireworks!

Verbatim NWP is showing a Moderate Risk scenario. Of course things can change days out. Right now, 30% is justified per historical matches of this forecast pattern. It is too early to go 45%+ and at the same time pattern recognition backs up greater than 15%.

I have also questioned some forecasts earlier this season. A Dixie MDT was clearly just ENH due to moisture issues. The other one got hyped on social media, but SPC never bumped TOR%, not their fault. In this case I agree with SPC anyway.

[WhiteoutWX]

Among other concerns regarding VBV issues being discussed in here, the 12z GFS/Euro have cut back on CI signals along the dryline for Tuesday/Wednesday. GFS soundings show substantial capping over OK, especially central and southern OK. Both models still put out some precip but the trend has been towards less. Still early but something to watch. Subtle embedded short waves will likely be able to overcome such capping, and those won’t be properly modeled for days to come most likely. 

[jojo762]

5 minutes ago, WhiteoutWX said:

Among other concerns regarding VBV issues being discussed in here, the 12z GFS/Euro have cut back on CI signals along the dryline for Tuesday/Wednesday. GFS soundings show substantial capping over OK, especially central and southern OK. Both models still put out some precip but the trend has been towards less. Still early but something to watch. Subtle embedded short waves will likely be able to overcome such capping, and those won’t be properly modeled for days to come most likely. 

A lesser precip signal would seem to greatly benefit wednesday, imo.

[WhiteoutWX]

3 minutes ago, jojo762 said:

A lesser precip signal would seem to greatly benefit wednesday, imo.

Obviously we don’t want widespread warm sector precip, I was more talking about the precip signal along the dryline which, especially on the Euro, looks very meager. Again, not overly concerned yet, just an observation when comparing the 0z vs. 12z runs.

[Radtechwxman]

2 hours ago, andyhb said:

SPC is not forecasting for your chasing needs.

Why do you always have to get attitude with people? I was just making a statement. Never said they were. He was saying a slowing trend would be good but from a chasing standpoint it wouldn't. I can have an opinion. Thanks

[andyhb]

4 minutes ago, StormChaser4Life said:

Why do you always have to get attitude with people? I was just making a statement. Never said they were. He was saying a slowing trend would be good but from a chasing standpoint it wouldn't. I can have an opinion. Thanks

But you both were like "what's the point of a 30%"...

[Radtechwxman]

Just now, andyhb said:

But you both were like "what's the point of a 30%"...

My questions were strictly from the uncertainty of timing of the waves. Obviously if they time right this will very much be warranted if not more. Not saying they were wrong for doing it I was just shocked they did this far out given timing differences between models

[Drz1111]

16 minutes ago, StormChaser4Life said:

My questions were strictly from the uncertainty of timing of the waves. Obviously if they time right this will very much be warranted if not more. Not saying they were wrong for doing it I was just shocked they did this far out given timing differences between models

Given uncertainty in models at this lead time, even if there was agreement you'd never know the timing of the waves.   If you're not going to put out that sort of forecast given this pattern, hard to imagine what you'd ever put it out for.   That's why its a 30% and not a 100%.

[Radtechwxman]

Just now, Drz1111 said:

Given uncertainty in models, even if there was agreement you'd never know the timing of the waves.   If you're not going to put out that sort of forecast given this pattern, hard to imagine what you'd ever put it out for.   That's why its a 30% and not a 100%.

That's a valid point and can't disagree with that. Given the parameters in place some significant severe is def probable

[jojo762]

47 minutes ago, Drz1111 said:

Given uncertainty in models at this lead time, even if there was agreement you'd never know the timing of the waves.   If you're not going to put out that sort of forecast given this pattern, hard to imagine what you'd ever put it out for.   That's why its a 30% and not a 100%.

Indeed. A 30% on D6 doesn't equate to issuing like a high risk or anything of that nature. Given what models are currently showing a 30% would easily verify over the currently delineated area imo.

[andyhb]

The lack of height falls on Wednesday on the Euro is becoming more noticeable. Ridge downstream is too amplified.

And then you add the fact that the CMC has a more defined shortwave ejecting, but since the ridge downstream is too amplified, the mid/upper level wind fields turn to crapola...and lol.

[tornado_junkies]

Quote

Wednesday through Wednesday night, The upper level trough across
NV and southern CA will slowly move east into UT and AZ by 00Z
Thursday. The ECMWF and GEM have slower solutions and keep the
lee surface low across southeast CO and southwest KS. The ECMWF
shows the dryline only moving east into west central KS. A surface
cold front will slowly shift southward across northwest KS.
Surface and 850mb winds will back to the south and southeast ahead
of the dryline and south of the surface front across west central
KS. The vertical wind shear will be strong with 0-6 KM shear
around 50 KTS as a 60 KT H5 jet max rounds the upper trough across
the southwest US, and then lifts northeast across western and
central KS. Supercell thunderstorms will develop along the dryline
and ahead of the front. Given the backed surface winds with
strong veering winds aloft the 0-1KM SRH will probably be 200 to
400 J/KG. These discrete supercells will produce tornadoes, some
of which may be strong to violent, along with large hail and
damaging wind gusts. These supercell storms will probably begin to
congeal into line segments as they move northeast at 45 to 50
MPH. If discrete supercells can reach the western counties of the
CWA Wednesday evening, or if discrete supercells can form well
ahead of the dryline within the warm sector, then there may be
risk for a few strong tornadoes. This will be something we will
have to watch, so stay tune to the latest forecasts. Even if a
broken line of strong supercell updrafts develop, there may be a
tornado risk well into the evening hours across the CWA as strong
southerly 850mb winds of 50 KTS will keep the boundary layer
mixed, which will preclude the diurnal low-level inversion from
developing after sunset.

Topeka AFD

[OUGrad05]

1 hour ago, andyhb said:

But you both were like "what's the point of a 30%"...

I never said whats the point of 30% 

[OUGrad05]

27 minutes ago, andyhb said:

The lack of height falls on Wednesday on the Euro is becoming more noticeable. Ridge downstream is too amplified.

And then you add the fact that the CMC has a more defined shortwave ejecting, but since the ridge downstream is too amplified, the mid/upper level wind fields turn to crapola...and lol.

Some capping perhaps in the latest runs, which is probably a good thing.  Question of wave timing may be critical as well.  Still several days to sort this out.

[jojo762]

48 minutes ago, tornado_junkies said:

Topeka AFD

Holy... Bombs away at D6. That type of verbiage at D6 seems reckless, but given current model parameterized output (while there still are various issues that make it imperfect), I see no reason to not expect tornadic supercells on Wednesday. 

[MUWX]

48 minutes ago, jojo762 said:

Holy... Bombs away at D6. That type of verbiage at D6 seems reckless, but given current model parameterized output (while there still are various issues that make it imperfect), I see no reason to not expect tornadic supercells on Wednesday. 

Seems like more of a D2 AFD than a D6, surprised this hasn't been discussed more on here. 

[Indystorm]

Can anyone comment as to whether Topeka NWS AFD's tend to be gun ho or conservative?  This is strongly worded for the time period.

[jojo762]

20 minutes ago, Indystorm said:

Can anyone comment as to whether Topeka NWS AFD's tend to be gun ho or conservative?  This is strongly worded for the time period.

Ultimately depends on the forecaster, but KTOP generally likes to go into more detail in the days up-to an event than most WFOs. Also tend to be fairly aggressive with tornado verbiage in AFDs.

[OUGrad05]

1 hour ago, Indystorm said:

Can anyone comment as to whether Topeka NWS AFD's tend to be gun ho or conservative?  This is strongly worded for the time period.

Forecaster dependent.  We'll see if wording is slowly altered in later outlooks.  It's quite surprising to be honest.  I would say in my recollection Topeka as a general rule is very good.  Forecasters ultimately pull the trigger on the AFD though.  I'm very surprised at the D6 wording and frankly at this point basically taking it with a grain of salt.  

[bjc0303]

Topeka also has Ariel Cohen as their SOO from SPC. 

[weatherextreme]

Reed Timmer's thoughts regarding next week

 

 

More

TARGET AREAS for severe weather: damaging wind, hail (red) and significant severe weather/tornado potential (pink) for Sunday, April 29, 2018 through Wednesday, May 2! The potential outbreak days are Tuesday and Wednesday in central/southern Plains @breakingweather @Tornado_Safe

 

 

[Weatherdemon]

27 minutes ago, weatherextreme said:

Reed Timmer's thoughts regarding next week

 

 

More

TARGET AREAS for severe weather: damaging wind, hail (red) and significant severe weather/tornado potential (pink) for Sunday, April 29, 2018 through Wednesday, May 2! The potential outbreak days are Tuesday and Wednesday in central/southern Plains @breakingweather @Tornado_Safe

Not much to disagree with given the trends of the last couple of days.

[WhiteoutWX]

No forecaster has all the answers at this point. It’s best to take any forecast at 4+ day leads with a grain of salt.

[bjc0303]

00z Euro could possibly have just taken the lid off. Broad negative tilt wave embedded in the larger mean western pos tilt trough. Strong flow throughout the troposphere with instability, moisture, and wind shear all in place. Considering how rock solid the euro has been here, would be concerned if I were a forecaster at one of the various potentially impacted CWAs.

 

Long way to go for sure, but this is shaping up to be something of significance on Wednesday. 

 

 

[jojo762]

SPC greatly expanded the 30% area for Wednesday (D5). Also now using the tornadic supercell wording, and mentioning possibility of strong tornadoes.

[OUGrad05]

SPC greatly expanded the 30% area for Wednesday (D5). Also now using the tornadic supercell wording, and mentioning possibility of strong tornadoes.

Eh, they didn't really expand it much, just added some to the western edge. I am starting to worry about an overnight threat further east of the 30%.

Still talking about a D5 forecast here though.

Like you the wording is concerning, it's a strong outlook for a D5 and ingredients are coming together.

Sent from my Pixel 2 XL using Tapatalk

[Drz1111]

Isn’t Monday potentially kind of a decent chase day?  Spatially limited but it looks like a few storms should fire on the dryline, especially if you get orographic help from the caprock, and what does form almost certainly will spin and not have other storms interfering. Worst case, LCLs are a bit high and you get some photogenic LP storms; best case you have a few slow moving tornados on open land...