Absolute Vorticity

CVG is up to 0.41" of rain as of 6am.

.25” here

Good Morning and some much need rainfall. Waves of rain will be the key today and should have another one in the next hour or two. Between waves you still have some light rain and drizzle. Looks like Helene made landfall just after 11pm last night so a few hours earlier than I thought would happen. I see a high wind warning has been issued and we don't many of those during a year. No changes otherwise though always one concern is the waves coming over the mountains you can get a downslope and this can dry things out in eastern Kentucky at times. Does that possible drier air move this far west and could be close at time especially folks east of I-71. At this moment will just do a wait and see but with all storms there are always a few items that you must keep an eye on. Nice to see the light rain at first to get the top layers wet especially in the area where folks got less rain earlier this week. Still going 2-4 by Sunday night and no reason to change and really it will be those waves later today that will make or break the forecast. 2 inches looks likely for most folks locally and again its the waves this afternoon will determine if we get closer to 4 inches. Of course we have more rain tonight and Saturday which will add to the totals and even Sunday a few showers as well.

So far at Cvg we have got 0.44 inches. Saw some models concerning wind gusts and some have us near Hurricane force at times. That may be a tad high imo but getting between 50-60 seems possible at times.

tpweather wrote: ↑Fri Sep 27, 2024 7:00 am So far at Cvg we have got 0.44 inches. Saw some models concerning wind gusts and some have us near Hurricane force at times. That may be a tad high imo but getting between 50-60 seems possible at times.

Agreed Tim. I've been going with 50-60 mph gusts for a while now. I don't see any need to change it. The track of Helene and how quickly the low weakens as well as the speed that it's moving will be key to getting those stronger winds in here.

Don’t look now , but center of circulation is in South Carolina per satellite, starting to wonder about how this much eastward lean is going to affect the capture

The capture has definitely turned into a nowcast situation. Anything about the track from NHC at this point should be avoided

Bgoney wrote: ↑Fri Sep 27, 2024 7:45 am Don’t look now , but center of circulation is in South Carolina per satellite, starting to wonder about how this much eastward lean is going to affect the capture

Yeah... much further East then expected even on the modeling. Tim's previous hood down in Greenville is getting hammered with strong winds and very heavy rain. Atlanta dodged a bullet but the foothills of the Carolinas are taking it in the chin big time!

From the Greenville NWS - My Gosh!

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Greenville-Spartanburg SC
717 AM EDT Fri Sep 27 2024

...FLASH FLOOD EMERGENCY FOR PICKENS AND OCONEE COUNTIES...

The National Weather Service in Greenville-Spartanburg has extended
the

* Flash Flood Warning for...
Oconee County in upstate South Carolina...
Pickens County in upstate South Carolina...

* Until 430 PM EDT Friday.

* At 717 AM EDT, emergency management reported hundreds of trees
down preventing rescue operations. Shelter in place and do not
travel unless fleeing floodwaters. Significant flooding is ongoing
in multiple locations, resulting in road closures, first-floor
inundation, and damage to some structures. The risk of
life-threatening landslide activity continues to increase in the
South Carolina mountains. Between 5 and 8 inches of rain have
fallen. The expected rainfall rate is 1.5 to 2.5 inches in 1 hour.

This is a FLASH FLOOD EMERGENCY for Pickens and Oconee Counties.
This is a PARTICULARLY DANGEROUS SITUATION. SEEK HIGHER GROUND NOW!

HAZARD...Life threatening flash flooding. Heavy rain producing
flash flooding.

SOURCE...Emergency management reported.

IMPACT...Life threatening flash flooding of creeks and streams,
urban areas, highways, streets and underpasses.
Extensive flooding of homes and businesses.
Widespread road closures. Widespread life-threatening
landslide activity.

* Some locations that will experience flash flooding include...
Easley, Clemson, Seneca, Walhalla, Pickens, West Greenville,
Welcome, Central, Pendleton, Liberty, Westminster, Gumlog, Norris,
Six Mile, Tallulah Falls, Salem, Lake Keowee, Keowee Toxaway State
Park, Devils Fork State Park and Lake Jocassee.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move to higher ground now! This is an extremely dangerous and
life-threatening situation. Do not attempt to travel unless you are
fleeing an area subject to flooding or under an evacuation order.

Heavy rain is significantly increasing the risk of landslides,
especially in areas where slides have occurred in the past. Slides
can destroy single homes and other structures and large sections of
roads. If you are in the warned area, you should not travel, except
to move away from flash flood or landslide dangers. If you are in
the vicinity of a stream near the heavy rainfall, especially on a
mountainside, or at the base of a mountain or in a cove, move
immediately to a safer location.

Turn around, don`t drown when encountering flooded roads. Most flood
deaths occur in vehicles.

In hilly terrain there are hundreds of low water crossings which are
potentially dangerous in heavy rain. Do not attempt to cross flooded
roads. Find an alternate route.

&&

LAT...LON 3450 8307 3460 8316 3460 8317 3461 8323
3470 8335 3482 8331 3482 8327 3493 8316
3494 8311 3500 8310 3509 8278 3505 8275
3507 8257 3501 8259 3502 8254 3498 8255
3483 8248 3467 8279 3447 8300

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CATASTROPHIC
EXPECTED RAINFALL RATE...1.5-2.5 INCHES IN 1 HOUR

We can add the ICON to the list (Euro/GFS) that kicked the crap out of the NHCs hurricane models as far as track goes

0.47" as of 8am at CVG. 0.57" at the Boone Co mesonet site.

Kiln- .29” . Kcmh- .08”

Latest thoughts from the boys just before 7am:

.NEAR TERM /UNTIL 8 PM THIS EVENING/...

Helene will get pulled northwest and then westwards across
Kentucky today as it transitions into an extratropical low.

Initial area of light rain across the region early in the day is
forecast to diminish a bit after daybreak as a bit of dry slot
precedes the core of the rain with the storm. But then as
Helene makes its closest approach and pivots past the forecast
area this afternoon, a large band of tropical rain will pass
through the region. This may bring a substantial amount of rain,
1 to 3 inches, from the lower Scioto Valley into the Whitewater
Valley with the highest amounts expected across Kentucky
counties and then into the Tri- State. Even though it has been
so dry previously, this amount of rain will likely lead to some
minor flooding as well as some substantial rises on smaller
creeks and streams.

Another concern is the wind which will steadily increase through
the morning as the system approaches and the pressure gradient
tightens. Winds will become rather strong in the afternoon with
most guidance in rather good agreement sweeping a band of high
winds across the area, starting in northeast Kentucky around
midday and then progressing northwest then west across the Tri-
State and lower Miami Valley, exiting eastern Indiana in the
late afternoon/early evening. Once again, the trend has been
towards higher wind speeds and this necessitated an upgrade to a
high wind warning for much of the southern part of the forecast
area. Further north and east, winds will still be gusty and peak
during the afternoon, but they will not be quite as strong. All
indications are that the strongest winds will decrease fairly
quickly from southeast to northwest late in the day heading into
the early evening.

Based on the latest radar loop, the center is along the GA / SC border and the center should get slung thru Eastern TN then begin to move back to the NW. The question for us with regards to heavy rain and the stronger winds predicted for later this afternoon and evening, will be if the low travels thru TN or KY. If it's thru KY the guidance is right and the forecast for those stronger winds should also be right. If the low stays in TN, then the heavier rains and stronger winds will miss to the south, We will be nowcasting this system for the rest of the day but that's my current thinking at this time.

tron777 wrote: ↑Fri Sep 27, 2024 8:24 am Based on the latest radar loop, the center is along the GA / SC border and the center should get slung thru Eastern TN then begin to move back to the NW. The question for us with regards to heavy rain and the stronger winds predicted for later this afternoon and evening, will be if the low travels thru TN or KY. If it's thru KY the guidance is right and the forecast for those stronger winds should also be right. If the low stays in TN, then the heavier rains and stronger winds will miss to the south, We will be nowcasting this system for the rest of the day but that's my current thinking at this time.

It's still headed due north right now through the Western tip of South Carolina. If it doesn't start turning northwest soon it's going to miss Northern Tennessee altogether. Seems to me a Southern or Central Kentucky route is the most plausible at this point. That being said, the upper low still has time to draw it into northern Tennessee. The more rain we get the better, but that would also mean more wind. Going to be a rainy windy afternoon and evening for sure.

Drove home from Myrtle Beach yesterday, either way from there has potential flooding, came home I-77, I-64 to 35 routes and it was not fun through mountains could only imagine today.

dce wrote: ↑Fri Sep 27, 2024 9:10 am

tron777 wrote: ↑Fri Sep 27, 2024 8:24 am Based on the latest radar loop, the center is along the GA / SC border and the center should get slung thru Eastern TN then begin to move back to the NW. The question for us with regards to heavy rain and the stronger winds predicted for later this afternoon and evening, will be if the low travels thru TN or KY. If it's thru KY the guidance is right and the forecast for those stronger winds should also be right. If the low stays in TN, then the heavier rains and stronger winds will miss to the south, We will be nowcasting this system for the rest of the day but that's my current thinking at this time.

It's still headed due north right now through the Western tip of South Carolina. If it doesn't start turning northwest soon it's going to miss Northern Tennessee altogether. Seems to me a Southern or Central Kentucky route is the most plausible at this point. That being said, the upper low still has time to draw it into northern Tennessee. The more rain we get the better, but that would also mean more wind. Going to be a rainy windy afternoon and evening for sure.

Yeah... we will see those 50-60 mph wind gusts IMO if the low gets into Central KY, which a lot of the guidance was showing yesterday and thus the high wind warning that ILN upgraded us too. Definitely going to be a tough drive home from work if things continue to evolve as expected. Current wind gusts over Central and SKY are in the 30-45 mph range at this time.

It’s still following the stalled frontal boundary atm

The low center, per SPC mesoanalysis as of 9am, was at 980 MB moving into the upstate of NC, eventually moving into the Smokies of East TN.

Is that the ULL near the Tenn/AL/MS border??

Bgoney wrote: ↑Fri Sep 27, 2024 9:32 am Is that the ULL near the Tenn/AL/MS border??

Yes Sir... that is where the 500 MB or upper low is located per SPC mesoanalysis at 9am.

That's a very heavy band of rain headed for Southern Ohio. Probably some gusty winds embedded in that as well.

dce wrote: ↑Fri Sep 27, 2024 9:41 am That's a very heavy band of rain headed for Southern Ohio. Probably some gusty winds embedded in that as well.

I'd say based on obs in SKY that gusts to 50 mph certainly possible with that band. One of the outer bands from Helene.

The center of Helene is now near Pidgeon Forge, TN looks like it's headed towards Knoxville.