Alberto remnants

[Hoosier]

Pretty good model agreement on the remnants of Alberto moving into the Ohio Valley/Great Lakes area as enough ridging prevents an early recurve.  As mentioned in the May thread, I could only find one system of tropical/subtropical origin to affect the region prior to June 1, so this is quite unusual to get something this early.

Details to be worked out but it looks like perhaps 1-2" with some locally higher amounts possible, and considering how dry it has been across a large part of the region, this will be a welcome sight.  Also may have the possibility for some severe weather, at least in isolated fashion. 

 

[snowlover2]

36 minutes ago, Hoosier said:

Pretty good model agreement on the remnants of Alberto moving into the Ohio Valley/Great Lakes area as enough ridging prevents an early recurve.  As mentioned in the May thread, I could only find one system of tropical/subtropical origin to affect the region prior to June 1, so this is quite unusual to get something this early.

Details to be worked out but it looks like perhaps 1-2" with some locally higher amounts possible, and considering how dry it has been across a large part of the region, this will be a welcome sight.  Also may have the possibility for some severe weather, at least in isolated fashion. 

 

SPC makes a small mention in the 4-8 day outlook. Would think Ohio would be in the best spot for possible severe with the center appearing to track through IN.

Quote

Day 4-8 Convective Outlook 
   NWS Storm Prediction Center Norman OK
   0345 AM CDT Sat May 26 2018

  Days 5-6, the merging of the upper trough with
   remnants of Alberto cast additional uncertainty into the convective
   forecast, and thus once again will defer until later outlooks to
   give a more confident assessment of severe potential into the Great
   Lakes/Ohio Valley areas.

   ..Goss.. 05/26/2018

 

[Hoosier]

To give an idea of how anti-climo this setup is, here are the May tracks... in addition to the recently discovered 1863 "Amanda" since it is not on the main map

[Indystorm]

Yep, we do need some rain down here in central IN whatever the source.  It will be interesting to see how this unusual event progresses.

[Stebo]

Bring it on, I want to break the all time monthly record here at Detroit.

[Stebo]

I find it interesting that the models show the low now going over western Indiana, actually would put a wide area in the psuedo warm sector/right front quadrant of the remnants with a very moist highly sheared atmosphere over southern MI, IN and OH. Definitely something to watch going into Wednesday.

[Hoosier]

25 minutes ago, Stebo said:

I find it interesting that the models show the low now going over western Indiana, actually would put a wide area in the psuedo warm sector/right front quadrant of the remnants with a very moist highly sheared atmosphere over southern MI, IN and OH. Definitely something to watch going into Wednesday.

It's also transitioning into a more tropical system now.  

Even though it won't have much strength at landfall, it does seem to maintain the enhanced flow/shear profiles into the Lakes/OV.

[Chicago Storm]

Looks like there will be a swath of 1-5” of rain across portions of E. KY/IL/IN/SE. WI/S. MI.


.

[Stebo]

1 hour ago, Hoosier said:

It's also transitioning into a more tropical system now.  

Even though it won't have much strength at landfall, it does seem to maintain the enhanced flow/shear profiles into the Lakes/OV.

The sheared junk systems are the one that end up producing more tors than expected. I am feeling this will be the case with Alberto.

[Hoosier]

6 hours ago, Stebo said:

The sheared junk systems are the one that end up producing more tors than expected. I am feeling this will be the case with Alberto.

Maybe.  Haven't really looked at the forecast soundings much yet, but here's one from just over the MI/IN border.  The SRH isn't that impressive but there's good turning in the lowest km.  And as usual a very moist low level airmass which leads to very low LFC/LCL heights. Will have to watch those bands/arcs of showers/storms

[Hoosier]

Surface low actually goes a tad west of here on the 00z NAM.  Could be a relatively close pass either way.

[UMB WX]

where was that track in winter

My greedy QPF side could pass the rain on to those in much more need for sure.  Mosquito's  and grass cutting every 3 days has become not very pleasant aspects of being outdoors but that's life.  Its just a little different times IMBY compared to the last few early springs and summer of lack of bugs and multiple grass cuttings a week.

Cool system for wx nerds nonetheless - enjoy

[wisconsinwx]

21 minutes ago, UMB WX said:

where was that track in winter

My greedy QPF side could pass the rain on to those in much more need for sure.  Mosquito's  and grass cutting every 3 days has become not very pleasant aspects of being outdoors but that's life.  Its just a little different times IMBY compared to the last few early springs and summer of lack of bugs and multiple grass cuttings a week.

Cool system for wx nerds nonetheless - enjoy

Those are hassles I could live with, except mowing on a sultry day like today.

[UMB WX]

lol

[Hoosier]

May get a window of some decent gusts east/southeast of the center as it passes by... in the area with better mixing.  Will have to see how it plays out but some guidance is suggesting a brief period near/over 40 mph possible.

[Hoosier]

  ...Great Lakes...
   The remnants of Alberto will move north through parts of the central
   Great Lakes.  Stronger low-level flow in the northeast quadrant will
   enlarge hodographs.  Lapse rates will be poor but very moist low
   levels and the background low-level wind field may support a few
   weakly rotating updrafts coincident with the diurnal cycle.

 

[Hoosier]

Starting to get in range of this

Should be a nice band on the western flanks wherever that is... it's a bit farther west on other models.  Very efficient precip producer in general given widespread pwats over 2" 

[snowlover2]

ILN now mentioning isolated tornadoes possible on Wednesday.

Quote

Area Forecast Discussion
National Weather Service Wilmington OH
332 PM EDT Mon May 28 2018



.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
The center of the remnants of Alberto will move across western
Indiana on Wednesday.  Although the center is not expected to move
across the area, showers and some thunderstorms are expected on
Wednesday as moisture is drawn up into the region.  With the
remnants of Alberto, there will be some isolated potential for
tornadoes, primarily across western portions of the region.  In
addition, some heavy rainfall will also be possible.  The clouds and
precipitation on Wednesday will keep temperatures lower than they
have been recently with high temperatures generally in the upper 70s
to lower 80s.

 

[snowlover2]

IND thinking progression could be slower than modeled.

Quote

Area Forecast Discussion
National Weather Service Indianapolis IN
417 PM EDT Mon May 28 2018



.SHORT TERM /Tuesday through Thursday/...

Issued at 206 PM EDT Mon May 28 2018

Mainly Dry weather still looks in play for Tuesday. The GFS and
and NAM continue to push the tropical system northward toward the
Ohio Valley. However best moisture still has they to arrive.
Forecast soundings continue to show mainly a dry column with some
convective possibilities in the afternoon. Forecast soundings show
attainable convective temperatures in the mid 80s with moderate
CAPE values over 1300 J/KG. Given this...will start Tuesday out as
dry and try to trend toward chance pops for the
afternoon as convection begins. Will trend best pops across the
southern parts of the forecast area as best moisture and
instability will found there.

On Tuesday Night...GFS forecast soundings begin to show deep
saturation. Good lift appears to arrive as the tropical low is
expected to reach western kentucky and the associated flow aloft
shows a negatively tilted upper trough over Indiana. PWATS surge
to over 1.90 inches. Thus will trend pops higher than the builder
blends on Tuesday night as these features arrive. Given the
expected clouds sand rain...will trend lows at or above the
forecast builder blends.

Wednesday should be a wet day. The GFS and NAm suggest the
tropical low will continue its progression across the state with
ample moisture. Forecast soundings remain deeply saturated while
PWAT rise even more. PWATS surge over 2.00 inches through the day
on Wednesday. Will trend toward 90-100 pops with these favorable
dynamics in place. Also given the expected rain temps should be a
bit cooler than the forecast builder blends. Caveat with tropical
systems...progression could be a bit slower than the model
anticipate. The GFS and NAM often trend to progress tropical
system progress northward faster than what actually occurs. This
being said...a 6-12 hour delay in the progression would not be
surprising.

At this moment the GFS and NAM push the upper system out of the
area on Wednesday night and Thursday. Meanwhile aloft an upper
trough still remains in place and another short wave appears to
approaching from the northwest within the flow. With the departure
of the tropical system...forecast soundings appear to begin to
dry out and show more convective instability by Thursday with
attainable convective temps...steep lapse rates and CAPE over 3000
J/KG. Thus given this...along with possibility of a slower
progression of the tropical system...we will need to keep pops in
the forecast on Wednesday night and Thursday. Will stick close to
the forecast builder blends on Temps at this point due to
uncertainty with the progression.

 

[OHweather]

One thought is the disorganized nature of the system with a lot of dry air on the right side may bode well for severe prospects, as it’ll increase the solar insulation on the very moist airmass and yield half decent instability.  Shear profiles aren’t fantastic, but low-level hodographs on the models are marginally big enough for some updraft rotation.  As mentioned above the tropical airmass will result in low LCLs/LFCs and the strongest shear will be in the lowest 2-3km which may offset the weaker deep-layer shear a bit and allow for mainly transient updraft rotation with potential for locally damaging winds and some weak tornadoes.  The threat will be south of the Ohio River for Tuesday, but have to think on Wednesday during the afternoon when daytime heating is maximized that some arcs of storms could develop across eastern IN, SE MI and into OH with some severe threat.  Poor lapse rates yielding skinny CAPE and very wet profiles limiting evaporation will limit downdraft intensity...and fairly modest deep-layer shear may limit sustained strongly rotating updrafts.  So ultimately think transient rotation may yield marginally severe straight-line gusts in the strongest cells.  With just enough low-level SRH and low LCLs there will be some tornado potential, but suspect the lack of stronger bulk shear and only “okay” amounts of low-level helicity will limit the risk of stronger tornadoes and also probably keep the number of tornadoes from being too impressive.  

[Hoosier]

7 minutes ago, OHweather said:

One thought is the disorganized nature of the system with a lot of dry air on the right side may bode well for severe prospects, as it’ll increase the solar insulation on the very moist airmass and yield half decent instability.  Shear profiles aren’t fantastic, but low-level hodographs on the models are marginally big enough for some updraft rotation.  As mentioned above the tropical airmass will result in low LCLs/LFCs and the strongest shear will be in the lowest 2-3km which may offset the weaker deep-layer shear a bit and allow for mainly transient updraft rotation with potential for locally damaging winds and some weak tornadoes.  The threat will be south of the Ohio River for Tuesday, but have to think on Wednesday during the afternoon when daytime heating is maximized that some arcs of storms could develop across eastern IN, SE MI and into OH with some severe threat.  Poor lapse rates yielding skinny CAPE and very wet profiles limiting evaporation will limit downdraft intensity...and fairly modest deep-layer shear may limit sustained strongly rotating updrafts.  So ultimately think transient rotation may yield marginally severe straight-line gusts in the strongest cells.  With just enough low-level SRH and low LCLs there will be some tornado potential, but suspect the lack of stronger bulk shear and only “okay” amounts of low-level helicity will limit the risk of stronger tornadoes and also probably keep the number of tornadoes from being too impressive.  

Yeah, any tornadoes should be weak in this setup. Could be one of those days with a lot of "interesting" low hanging clouds.

[snowlover2]

3K NAM slowed it down much like IND mentioned could happen. Lots of convection develops in IN/OH/MI on Wednesday.

[Hoosier]

[Stebo]

1 hour ago, OHweather said:

One thought is the disorganized nature of the system with a lot of dry air on the right side may bode well for severe prospects, as it’ll increase the solar insulation on the very moist airmass and yield half decent instability.  Shear profiles aren’t fantastic, but low-level hodographs on the models are marginally big enough for some updraft rotation.  As mentioned above the tropical airmass will result in low LCLs/LFCs and the strongest shear will be in the lowest 2-3km which may offset the weaker deep-layer shear a bit and allow for mainly transient updraft rotation with potential for locally damaging winds and some weak tornadoes.  The threat will be south of the Ohio River for Tuesday, but have to think on Wednesday during the afternoon when daytime heating is maximized that some arcs of storms could develop across eastern IN, SE MI and into OH with some severe threat.  Poor lapse rates yielding skinny CAPE and very wet profiles limiting evaporation will limit downdraft intensity...and fairly modest deep-layer shear may limit sustained strongly rotating updrafts.  So ultimately think transient rotation may yield marginally severe straight-line gusts in the strongest cells.  With just enough low-level SRH and low LCLs there will be some tornado potential, but suspect the lack of stronger bulk shear and only “okay” amounts of low-level helicity will limit the risk of stronger tornadoes and also probably keep the number of tornadoes from being too impressive.  

Great summation that I completely agree with.

[Hoosier]

It's gonna be rip city in that band west of the center.  Looks like there may be enough instability for thunderstorms even there as well, which would obviously enhance rainfall rates/amounts.

[Stebo]

DTX's thoughts are pretty much in line with what we are mentioning here.

Quote

Concern is beginning to increase in the 18z-03z timeframe Wednesday
afternoon/evening. During this period, the center of Alberto will be
approaching the Michigan/Indiana border, with increasing low-level
flow over southeast Michigan. East/southeast flow will back with
height, with large curved hodographs developing as 0-1km bulk shear
increases to an impressive 20-30 knots along with SRH values of 100-
200 m2/s2. This kinematic field coupled with the instability present
may yield discrete, low-topped cells to develop, with the potential
for rotating updrafts. Because of these factors, the Storm
Prediction Center has included much of southeast Michigan in a
Marginal Risk for severe weather for the possibility of an isolated
tornado. Will continue to monitor this threat closely over the next
24 hours, as there still remains details to be sorted out in the
boundary layer stability profile. Despite weak midlevel lapse rates,
the tropical environment that will be in place, coupled with low LCL
heights and with the ambient wind field can only need roughly 500
J/kg of CAPE to create an increased risk for possible isolated
tornadoes.

 

[HillsdaleMIWeather]

Wouldn't be surprised to see some Flash Flood Watches get hoisted

[TimChgo9]

At least Wednesday will be interesting.  

Otherwise, it's been a boring spring.   

[HillsdaleMIWeather]

3K NAM looks pretty gnarly 

[OHweather]

The 12z NAM actually deepens the low a few mb during the day tomorrow.  Upper-level divergence is weak with a very modest flow at 300mb, and the low and mid-levels aren't strongly baroclinic with weak temperature gradients around the low, so not sure what the mechanism for deepening the low is.  Alberto's remnants will interact with a weak but negatively tilted 500mb shortwave over the upper Midwest tomorrow which may add some modest large-scale upward motion and perhaps enhance convection near the low during the day which may result in a slight deepening...the Euro also deepens it slightly during the day Wednesday...but this definitely isn't anything like Ike where stronger baroclinic sources deepened the low.  That said, the NAM and Euro both have enough of a LLJ that with some heating there could be decently gusty winds east/southeast of the low track Wednesday afternoon, possibly on the order of 30-40MPH.  If the low is as deep as those models depict that could be enough for some mild wind impacts. 

The heavy rain west of the center has been mentioned by Hoosier and others and could produce some flash flooding.  There's a weak SE'rly LLJ advecting in very moist (PWAT greater than 2") air north of the low on Wednesday, with some lift from the aforementioned shortwave trough over the upper Midwest and also some deformation between 850mb and 500mb west/northwest of the low.  That lift combined with the very high PWAT, and favorable instability profiles (weak instability but long, skinny CAPE on model soundings) will certainly yield some heavy rain rates in rain/convection west of the low track.  The good news is the low itself will be moving along at a modest pace, not super fast but not extremely slow either, but it would only take a couple hours or so of good rain in some areas to get enough to cause flash flooding, so I'm sure there will be some in that area of heavier rain west of the center.  Even east of the center scattered convection in the high PWAT air could cause some issues, especially if there's any training or areas that see multiple storms.

I like the SPC's marginal risk at the moment.  The NAM, with its slightly deeper low, has stronger low-level wind fields and more impressive helicity across eastern IN/SE MI/western and centrtal OH Wednesday afternoon and evening...with effective SRH of over 200 m2/s2 on some soundings from that area during the later afternoon and into the evening.  Bulk shear is still more modest at 25-30kt on the NAM across the area of interest which would make it difficult to see persistent and strong mesos with any cells, but the stronger low-level shear and low LCLs would make some brief/weak tornadoes more likely, perhaps enough to get a 5% TOR risk from the SPC.  CAMs agree on a good number of cells developing east of the low, so if the shear comes in a bit higher there could be some tornadoes.  But, that's dependant on the low deepening a few mb during the day Wednesday, which I'm not necessarily sold on.