Wednesday update

Forecast seems to be on track...
Upper low that brought the cool and cloudy conditions the past couple of days is now well east...
Surface high pressure is also slipping east of the region allowing for a return of southerly breezes and warm air.
Weather the next 2 afternoons will be very nice... Great for both the Steamboat race and also the Pegasus Parade.

Moisture will begin to increase across the regionon Friday as a very intense H5 shortwave / upper low move into the central plains. For us on Friday, expect lots of high / mid clouds along with gusty southerly winds. Temperatures will climb into the upper 70s to near 80.
In my previous post I mentioned how I like the movement and speed of the upper low on the ECMWF data and not the quicker GFS,... well guess what??? the GFS has finally come around to that solution and is now very similar to the ECM. As a matter of fact, all models are now pretty much agreeing on the movement and speed of this system through Saturday evening.

Okay, so what does it mean for Oaks and Derby ??? Certainly warm temperatures will be the rule... We've been talking about highs near 80 for Oaks and in the 70s for Derby all this week so far - warmest in the market place... It looks like that forecast should work out real well, as the cooler air from this system won't arrive until later on Saturday or Saturday night. By Sunday... temperatures may actually hold in the cool 50s with low stratocu clouds around pretty much all day as the upper low will still be spinning in the Ohio Valley.

Rain chances....
Dry through Friday morning... NAM is the most aggressive with rain chance on Friday afternoon - but to me... it looks to bullish. I do think there will be a few widely scattered showers or storms around Friday afternoon - especially west and northwest of Louisville. Having said that... if you are heading to the track for Oaks... take your poncho / rain gear just in case - I'd rather you be safe than sorry.
Friday night - Rain and thunderstorm chances really ramp up. Lead vort lobe and sfc convergence zone (very nearly a dry line set up) will push into the region... These storms will likely be severe west of us Friday evening, but as they outrun the best dynamic support and the instability wanes as we go deeper into the night, the storms will likely be in a weakened state by the time they reach our area.
This is the first batch and most widespread batch of wet weather we will have with this system.
Another round of scattered showers and storms will likely develop Saturday afternoon from near Louisville and points east as another strong lobe of vorticity and another convergent boundary (the true cold front with this system) move across the viewing area. By race time (the run for the roses), the second batch of showers and storms should be east of the track... although the track may still be somewhat muddy.

Enjoy the rest of the festival

Later:
Jay

Monday Late Night Update

Alright.. the cold air is here... it will stick around through Wednesday morning then it's back to a nice warming trend...
H9 and H85 moisture running pretty high across the region late tonight into tomorrow so low StatoCu type clouds expected from time to time into Tuesday afternoon.
Upper ridging builds in for Wednesday and Thursday.
H85 temps start climbing and head for +6 to +8C for Wednesday and +11 to +13C for Thursday.
Mixing schemes support near 70 on Wednesday and near 80 Thursday.
Bottom line, both the Steamboat race's and Pegasus Parade's weather looks great !!

Upper system progged to move into the Central Plains on Friday. Surface system associated with this H5 energy is expected to occlude later on Friday as system becomes more vertically stacked with time. Big deal you say ??? well you're right - what does it mean for us ???
I'll tell you what it means - increasing rain chances for both Oaks day and Derby day.
I'm not talking about an all day soaker type rainfall - in fact there will be plenty of dry hours these two days. But at this time it looks like the best chances for rain will come with a weakening frontal boundary (resembling a dry line) Friday night and then another chance on Saturday afternoon with a surface trough (true cold front) and increasing Diff PVA.
Sorry for the lack of maps this post but it's late and I'm goona catch some zzzzz's. I will say this,
I'm leaning towards the ECM for the out periods of this forecast (i.e. Oaks and Derby) because it has done a better job with speed, placement, movement. and intensity with the previous 2 upper systems that have closed off and virtually were cut off from the main flow - kind of like this one is progged to do.
Monday's 12z ECM supports decent rain chances Friday night and then again Saturday afternoon. Of course we'll keep a close eye and keep you updated on the timing of the rain chances because "chances are" there will be some changes to the rain timing as we get closer to the event.

Have a great night and Tuesday...
another detailed look at the late week system for you Tuesday night.

Later:
Jay

Sunday Morning Update (Strong / Few Severe Storms Monday Late day ??)

Active weather the next 48 hours as two weather systems affect our region...

Throughout Sunday, clouds are expected to be on the increase and low and thicken as the afternoon hours wear on. This will be in reponse to a H5 short moving east, southeast from the plains states.

Surface low pressure will develop on the boundary to our south and ride northeast towards WV.

WAA/overrunning will support the development of rain across our region by late day Sunday and Sunday night - so get any outdoor chores done by mid afternoon Sunday - beyond that, increasing chances for the wet stuff.

This first batch of rain ends late Sunday night with clearing skies into Monday morning.

Monday morning into early afternoon looks just fine to me - with a mix of sun and clouds and temperatures near 60.

Then our second system will begin to affect us by later Monday afternoon...

Another strong H5 jet/short will dig southeast into the Ohio Valley.

Strong H5 CAA at this time (notice H5 height falls) will create fairly steep lapse rates / modest instabilty over our area Monday afternoon. Notice the LI's and sfc based CAPEs progged by the NAM for Monday later afternoon....

As sfc wave / cold front drive southeast, low level convergence will add to an already stengthening vertical motion field induced by the strong dynamics digging into the region.

So what does all of this mean ??? Another round of showers and thunderstorms for later Monday afternoon into early evening. Because of the the strong CAA aloft and decent downdraft CAPE/low level T/Td spreads, I think a few of these cells produce hail and gusty winds to near severe limits. SPC does not a risk for the area... but would not be a bit surprised to see us with a SLIGHT in later outlooks

This system will clear the area Monday night with showers and storms ending from northwest to east/southeast across the viewing area. Low clouds will sweep into the Ohio Valley behind this system and likely continue to blanket the area into Tuesday afternoon but as the H5 jet lifts northeast and ridging takes hold, clearing skies should take over later Tuesday afternoon into the evening.

Wednesday and Thursday... Looks great !!! Upper ridging dominates these 2 days. A warm front will be lifting / redeveloping north of us by Wednesday afternoon. H85 temps in the 10 to 12C range should easily support mid/upper 70s again.

Thursday - large system developing out west but for us... upper ridging, S,SW flow in the low layers and H85 temps of 12 to 14C support lots of sun and temperatures in the 80 to 85F range for Thursday afternoon. Simply put... weather for both the Great Steamboat Race and the Pegasus Parade should be AWESOME.

Okay now onto Oaks and Derby....

Strong system developing to our west on Thursday will beging to slowly push east for Friday (Oaks) and Saturday (Derby). At this time, I do think we will have some rain during this period - certainly not continuous - but rain chances nonetheless.

The Sunday 00z run of the ECMWF would support two rounds of rain with this system.. one on Friday night and the other Saturday night. The Op GFS 00z Sunday run... Scattered showers and storms Friday afternoon - a solid line of showers and storms Friday night - dry but cool for Derby day. The DGEX Saturday 18z run - scattered showers and storms Friday afternoon, a good line of storms Saturday night, cooler but pleasanr for Derby Day

You get the drift.... rain chances return for Oaks and Derby day - although timing is still up in the air - and as you know, timing is everything for these two great days !!! We'll keep you updated.

Have a great rest of you weekend

Later:

Jay

Friday morning update

What a great stretch of warm weather we've had across the region...
Yet today will be another very warm day as temperatures climb back into the 80s on gusty south and southwest breezes .

Overall... a dry day is expected as there will be little / no forcing despite some modest instability.
Check out the afternoon progged CAPEs by the NAM.

Having said that... I do think an isolated storm or 2 could pop in the daytime heating...
main reason I say this... check out the conv T off the progged NAM sounding for later today (21Z). Forecast high temps will easily exceed this so some thermals may get to their LFC.

I still think a band of showers and storms is on the way for late tonight - but ending early in the morning on Saturday.

Strong H5 short moving from the plains up through the western lakes will force a cold front through the region overnight tonight. Good forcing on the boundary and increasing CAA aloft from the advancing short (i.e. steepening lapse rates) will be more than sufficient for showers and storms to form along the boundary.

SPC does have the day1 just west of us - they've actually expanded it eastward closer to us.
That outlook looks fine !. I don't see a large scale SVR event from this system for us, but there could be a few stronger cells capable of producing gusty winds and some hail - especially in the northwestern regions of the viewing area.

Front clears by morning... and I think most if not all the rain is out of here by 7 or 8am.
Bottomline... showers end very early with clearing skies by mid/late morning and a beautiful afternoon with tons of sunshine and (although cooler temperatures) pleasant conditions.


Sunday's weather looks decent at this point... Another strong H5 short - with several lobes of vorticity will be approaching the area. High clouds should be on the increase into the afternoon - but sufficient low-level moisture will be slow to return. As a result much of the day will be dry and mild. Late in the day towards evening, another cold front and developing surface low will move through the region. Scattered showers and a few storms will be possible at this time but this system won't pull adequate moisture into itself until it gets east of the I-65 corridor.
Bottomline - best coverage of showers and storms will likely occur over the eastern half of Kentucky - just east of Louisville.

Colder air moves in behine this boundary... H85 temps expected to be in the -3 to -1 C range.
That would support only low to middle 50s for highs on Monday - uggghhhhh!!!!!

have a great weekend all...

Later:
Jay

Monday Morning Update

Back from a real nice 1st Communion in Chicago for my brother's kids... Went up there last Friday and came back yesterday... Weather up there was great excepy for Saturday... Same upper system that camped out over us this past weekend gave Chi-town rain on Saturday as well. The trip down yesterday was wild.... Beautiful sunshine and warm temps from Indy north to low clouds and a chilly misty rain from about Scottsburg and points south into Louisville.

Another minor quake last night 4.5 centered basically in the same region as last week's - I felt last week's -(shook me out of bed!) but this one.... Nope!

Upper level low is now well east and pushing away. Very light winds in the atmosphere and a high moisture content meant the perfect scenario for some fog late last night and this morning. Inversion will break allowing for decent mixing this afternoon as lots of sunshine will be returning along with very pleasant temperatures.

Much of the week looks just fine. Large upper ridging will redevelop and amplify across the east as major troughing continue in the west. Numerous shortwaves will eject / travel through the western trough, but as they continue east/northeast - they will weaken substantially as they minor out when encountering the large ridging in place....
Bottomline, a couple of wesk systems will approach the Ohio Valley, but only a few clouds expected from time to time.
I don't see much (if any precip) until later Friday / Friday night when stronger H5 wave travels up and over the ridge through the Great Lakes with a trailing sfc boundary through here - Even then, precip should be scattered in nature as best dynamics pass well north. Having said that - we could be looking at some weather problems for the balloon glow Friday evening.

This system should clear nicely in time for the Derby festival events this weekend. Weather looks dry and pleasant for Saturday - good for the Mini / opening day at Churchill / only ? ... will the B layer winds be weak enough after this sfc boundary passage for the balloon race Saturday morning?? We'll have a much better handle on the meso (even microscale) patterns that will control this event by Wednesday of Thursday of this week

Quick look ahead... seems as if an amplified pattern may try to develop next week (Derby week). One large trough over the east / another over the far west, with large ridging inbetween... For us (if this pattern pans out) it would mean a couple of cool and cloudy days for early Derby week, then increasing sunshine and warmth by later Wednesday/Thursday. My data (that I use and think it's a world better than the GFS info this far out) does not go out to Oaks and Derby day at this time,,, but if you were to extrapolate - - I would say both those days look breezy and warm and dry right now... stay tuned !!!

Wednesday Night Update...

Forecast looks to be on track for the rest of the work week and the start of the weekend...
The only significant change from previous forecasts may come on Sunday.
It now appears that the upper level H5 low that is becoming cut off from the main jet will slowly meander across the Ohio Valley this weekend.











Scattered showers and a few rumbles will be likely beginning Friday night late - and continue Saturday - there's even a chance that some small hail could accompany any convection that can manage to form in the meager at best instability that will be around and the fact that H7 temps are -6 C near the center !! ... and now it looks like we will have to introduce pops into Sunday's forecast period as well.

The latest 00z run of the NAM has really slowed this H5 feature quite a bit - more in line with the 12z ECM if not even a little slower than the 12z ECM now - and it looks correct for a couple of reasons...

1) the low is cut off from the main jet
2) late Saturday night into Sunday morning - there's an H5 lobe (short/speed max) rotating around the low. As this short/lobe is rotating on the northern / western side of the H5 low center - it will further slow down the entire system.


















Once the speed max rotates south and east of the low center - it will finally pull the entire system east and out of the region - but this likely won't happen until later Sunday.

Bottom line - dry and beautiful through Friday... scattered showers and thundershowers later Friday night into Saturday and now into Sunday as well. Showers should end Sunday afternoon as the upper systems pushes east.

Later:
Jay

Monday morning update

Well not the world's best "Thunder" weekend - weatherwise.... actually very similar to what happened back in 2005.
Looking ahead, after tonight's chilly weather with a frost on the way - and a light freeze possible, we will enjoy a prolonged period of dry weather along with warming temperatures as ridging sets up over the eastern half as a very large trough develops way out west.
The only "fly in the ointment" comes later Friday into Saturday as most models have an H5 short cutting off and moving slowly east under the large upper ridge. This feature is progged to affect us later Friday into Saturday with our next shower/t'storm chance.

Timing of this feature is certainly not "set in stone" however, simply because it is getting cut off from the main jet and it is meandering easterly under the large upper ridge that will be parked across the east....

Next week, the ECMWF was suggesting quite a bit of Pacific energy would undercut the eastern ridge - this will likely be when the pattern gets quite active once again.

Enjoy the quiet weather while we've got it

Later:
Jay

Thursday Morning Update

Same story... forecast from previous days looks to be on track...
Severe thunderstorm outbreak on the way for areas west of us later today and this evening...
This area of storms will sluggishly work towards our area late tonight - timing looks to be well after midnight and more like after 2 or 3am.

Last night's severe MCS continues to weaken... But another strong H5 impulse now across TX/OK will ride northeast around the deep trough and trigger another round of storms.

This next batch of storms will initiate well west of our region along and close to a prefrontal trough that will be located from western IL - southwest through AR. These storms will likely be discrete in nature due to lack of any real good linear forcing - as true cold frontal boundary will be lagging farther behind the deep convection. This is the zone where the bext supercellular / strong tornado threat will exist.

See SPC's day 1.

Very late tonight, the storms will start to congeal into more of a line - or at least broken line segments as the area moves into our region. Although instability will be modest over us, a very strong LLJ will be in place as the storms move in. Some of these storms will likely "tap" the stronger wind field aloft and bring them down to the ground in the form of a damaging wind gust - or even a tornado spin-up along any bowing segments that can form.

This area of storms moves through late tonight / very very early Friday morning. Partial clearing will occur behind this convective cluster resulting in the atmosphere to "recover". See the progged sfc based CAPEs at 18z Fri....

Cold frontal boundary will advance eastward across the region Friday afternoon resulting in another band of storms... These storms will likely quickly form into a line due to the linear forcing along the boundary... and due to the more unidirectional wind shear that will be in place - the primary severe weather threats for Friday afternoon will be straight line winds and hail.

Weekend---- Not too nice !!! Dress warmly if heading to Thunder Over Louisville. Low / mid 50s for air show with skies becoming cloudy and mid / upper 40s for fireworks with cloudy/breezy conditions and likely some drizzle from time to time as low layers - H9, H85 etc.. become saturated.

Wednesday morning update

Yesterday's forecast for partly sunny skies and temps in the upper 60s to near 70 for today may be in huge trouble.... these lower clouds are lined up from just north of the Ohio river and points south... Previous data was showing this moisture scouring out and with with no inversion this afternoon, low level mixing suggested the upper 60s to near 70. This looks pretty doubtful now.
Latest RUC guidance holds on to the low level moisture well into the afternoon - pretty stationary band of 90%+ RH at H9 due to the stronger than forecast high pressure to our southeast holding things up.
In reality, looks like more of a low / mid 60s day for the metro with generally cloudy skies -

Severe threat....................
Last night's discussion looks to be on track... Thursday / Thursday evening looks mainly dry, windy and warm .... H85 temps and the fact that we will be well into the warm sector all afternoon suggest near 80 degree temps still quite possible.
Main outbreak (including the possibility for violent tornadoes) tomorrow afternoon / evening looks to be to our west - mainly in the moderate risk area that SPC has on their day2.

We will get this band of storms in here late Thursday night. The storms will be outrunning their best instability as they get here but the strong wind fields that will be in place still suggest a decent chance at some severe in our area as well - wind/hail/even isolated tornadoes on any bowing segment that form.

Atmosphere recovers behind this first batch of convection - new NAM has 1500 to 2000 sfc based CAPEs here by midday Friday.

As cold front pushed in -more storms will be likely. Strong dynamics in place suggest some of these storms will go severe - mainly for wind / hail.

Tuesday early evening update

Warm temps will continue across the region the remainder of the work week with even a very good chance that the mercury will climb close to 80 on Thursday afternoon !! This big influx of warm air will be caused by a potent storm system that will be developing across the plains the next 24 to 48 hours.

No doubt, this system will produce severe weather - the question for us becomes where and when.

Several pieces of jet energy will be moving through this developing deep trough the next several days. One piece will be responsible for severe weather on Wednesday across Oklahoma into TX. SPC has gone moderate there.

Another piece (and probably the most potent in the series as it will cause the H5 low to close off) will track through the central plains into the MO valley Thursday afternoon and evening. This will likely cause the biggest outbreak of severe weather with this system. SPC has moderate for areas west of us. Wouldn't be a bit surprised to see a HIGH risk included - to our west for Thursday.

This batch of severe weather will form into a line and start pushing in our direction late Thursday night. By the time the storms arrive here... there could still be some strong / severe cells but by that time of the night, many of the cells will likely start to weaken some as they move away from the best instability - let's hope this in fact pans out !!!! Severe weather is never a good thing - especially late at night.

This first batch of stormy weather should move through by early Friday morning. Partial clearing behind the convective line will allow for the atmosphere to recover - notice GFS's MLCAPES for midday Friday.

As the cold front sweeps through, storms will once again be possible. Strong dynamics will be in place at this time so the bottomline is that this second batch of storms on Friday could go severe - actually, Friday afternoon's storms may give us our greatest threat at severe weather with this system.

We'l' keep you updated...

Later:
Jay

Wednesday Night Update

Here we go again... another soaker on the way !!
Another heavy rain event on the way for our area. Here's the setup... a frontal boundary now to our south will slowly lift north towards the Ohio River over the next 24 hours. Warm, moist air will rapidly return north and overrun the boundary as a potent H5 shortwave rides the jet eastward toward the Ohio Valley.

Rain is expected to develop late tonight / early tomorrow along and north of the boundary. As the rain increases, temperatures will likely hold in the 40s north of the front but gradually warm to 60 or better south of the front. This strengthening baroclinic zone combined with an increasing LLJ (as the H5 short approaches) will produce a widespread heavy rainfall event.











Thunderstorms are expected to mix in during Thursday afternoon and especially Thursday night as the strong low level WAA at H9 creates a decent region of elevated CAPE over our area.
Check out the NAM progged sounding for tomorrow (Thursday) night. Notice the inversion below H9 and the CAPE available for a parcel lifted from the top of the inversion.









Both the NAM and GFS place the axis of heaviest rain very close to our region.

At this time, it looks like a widespread 2 to 4 inches of rain likely but with the expectations of convection mixing in and the fact that both models are progging PWs of ~1.5", would not be a bit surprised to localized 5 inch amounts.

No doubt, this much water will likely cause some hydro issues across the region - especially for the smaller rivers across southern Indiana and Kentucky - and a flood watch has been issued for all of the viewing area.

The good news... this weekend looks to be dry and mild.... Yes ! time to hit the golf course - if it's not too wet......

Later:
Jay