March 2021 Weather Discussion

[tpweather]

For severe wx concerns... the question will be, do we get showers and clouds most of the day Thursday which reduces the severe threat. Or, do we get a period of clearing so some instability can develop? Plenty of shear and helicity with this system and quite frankly, it won't take much CAPE to get things going. Damaging straight line winds would be the main hazard with this system should the stronger low solution be correct. We could also see brief isolated spin up's or QCLS tornadoes if you will, with the bowing segments. Don't see much of a large hail threat at this point. We have plenty of time to monitor this system and like I said this morning, the marginal risk is valid from the SPC at this time.

Great Post Les and wanted to add concerns about rain totals. The problem we have with these systems that have strong winds is these areas of stronger storms move through quickly and though you can get some brief heavy rain it usually does not last long so I may be on the lower end in terms of rainfall area wide though a local area can get a nice dose if timing is correct.

[tron777]

Thanks Tim... I think we could see up to an inch of rainfall if we get multiple line segments to move thru but that remains to be seen. I agree with you that this system won't be as slow of a mover as we've seen with the last several. The wind by far looks to be the major concern. Without storms, as I mentioned earlier, I can see gusts exceeding 40 mph. With t-storms, then we're in the 60+ mph category which of course can cause some problems. We'll just have to wait and see what happens with the guidance but definitely interesting to see the GFS take a step towards what the Euro has been consistently showing for several days now.

[tron777]

Oh and since some of you have brought up the vaccine... my folks had the Pfizer one for both shots and other then a sore arm for a day or two, they were fine. My Brother had his 1st shot yesterday, same thing. I had my 1st shot last week, same deal. So far so good.

[tron777]

67 at CVG as of 2pm... Euro is running now so we'll see what it does for Thursday here shortly.

[snowbo]

Pfizer here. Thankfully, no problems either time.

[cloudy72]

12z Euro still looking rather ominous for wind potential Thursday night into early Friday. 60+ mph gusts possible if this model is correct.

[tron777]

Euro isn't coming in quite as strong with the low today, but a similar track and still the strongest of most models anyway. Timing looks to be in that late afternoon thru early evening window. By midnight or so, we're done. (minus the wind, talking storm window here only) 0.65" for rainfall so props to Tim for mentioning that rainfall amounts might have been too high as originally estimated by the models due to the speed of this system. For severe wx… Dews get close to 60 at CVG. 10 M Wind gusts in that 50-55 mph range are showing up. CAPE values of 500 J/kg are also there. I'd prefer 1000, but we have plenty of time to iron out the details.

EDIT: Those values are for CVG. Definitely see 60+ mph as Mike mentioned for the I-70 Crew.

[tron777]

I hit 71 again today. CVG hit 70 - 2nd day in a row! We should do it again tomorrow.

[Bgoney]

Still not impressed with what the GFS and Nam offer for severe weather on Thursday. Morning rains , and off and on rains throughout the day in a cap-less environment does not bode well for severe thunderstorms.

EU scenario a different story, with possible isolated severe. Although Even EU atm has stepped downward for severe

[MVWxObserver]

Currently 64 here in G'ville. Progged for about 70 tomorrow dependent of course on how much (early) cloud cover and shower convection.

[cloudy72]

71 here as well for second day in a row

[tron777]

Afternoon discussion from the boys for Thursday:

A strengthening mid level short wave will lift northeast out of Texas
and into the mid Mississippi Valley through the day on Thursday. The
12Z GFS and ECMWF remain stronger than the NAM/CMC with this and
eventually develop a closed 5H low as it continues to shift into the
southern Great Lakes through Thursday night/Friday morning. An
associated developing surface low over the southern Plains/lower
Mississippi Valley on Thursday will also lift northeast and
strengthen through Thursday night as it tracks off to our northwest.
There remain some timing/placement and intensity discrepancies
between the models with this, but will continue to trend toward the
stronger GFS/ECMWF solutions as they have remained somewhat
consistent with the GEFS/Euro ensembles. Both the 12Z ECMWF and GFS
are showing a 70-80 knot 8H jet shifting across our area through
Thursday night with the ECMWF ensemble mean suggesting prob of wind
gusts > 34 knots at 90 percent across much of our area. This will
obviously be dependent on the strength and track of the low, but
with at least some significant high wind potential, will go ahead
and add a mention to the HWO. Given the wind fields, the other
concern will be the potential for severe weather. There remains some
uncertainties as to how much instability will be pulled up into our
area ahead of the low but it will not take much to support at least
a lower end severe threat Thursday evening into Thursday night. For
the sensible weather, will generally allow for an increasing chance
of showers and thunderstorms through the day on Thursday with
widespread showers and a chance of thunderstorms for Thursday night.
Highs on Thursday will be in the mid to upper 60s.

[tpweather]

Good Evening, Thursday brings all kind of forecast problems. I know the models are not showing an all out severe outbreak locally and understand when you look at some of the parameters but my main concern is the deepening of the low quickly and the track of the system plus timing. Always saw the strong winds with this system but how much sun will happen on Thursday. Still want to see the latest model runs on Wednesday but I am probably going with a little higher chance than I did earlier though not an all in severe outbreak.

Just to add and if Thursday becomes a day with rain then the severe threat is low and then will heavy rain and winds rather strong and steady all day. So tons to look at in the next 2 days.

[cloudy72]

Lots to discuss today - very active period next 48 hours. SPC Day 2 outlook now has slight risk up into SW Ohio, southern Indiana and all of Kentucky while a high wind watch has been issued effective Thursday night for Dayton, Columbus and northern Cincy burbs.

[Bgoney]

Models coming together overnight and joining the EU with a stronger low somewhere in the mid 980s. Gusty surface winds a given late in the day. Rain and some thunder from mid morning through the afternoon with no cap in place. Do we get a break of any kind and a surge of warmth and DPs before the cold front and possible squall line moves through in the evening ? Expect qpf ranges of .50-1.50" .

[tron777]

Good morning all! Excellent posts this morning as usual from you guys. I had some rain already this morning with the first small wave of activity. Temps should easily get back into the low 70s today. If enough sun is realized mid 70s are not out of the question. You guys have Thurs covered nicely. Agree with the two waves of rain idea. The first late Wed night into Thurs morning. A break then Thurs evening for the possible severe stuff. How much instability can we get is key during that break Thurs afternoon. All ingredients are there for severe storms but the degree of instability (as usual this time of year) is the key to success in this set up. Strong winds as you guys have mentioned will be an issue overnight even if we don't see severe wx. Don't really have too much else to add at this point since you all have done a wonderful job already.

[tron777]

0.02" from the showers moving thru this morning. Dews are up to 50 now. We'll see if we can reach 60 degree dews tomorrow afternoon. That would help our instability cause.

[BookNerdCarp]

I got 0.02 this morning as well.

[tron777]

StormTalk! https://www.wave3.com/2021/03/24/goode- ... ther-blog/

[cloudy72]

Only a trace in my hood this morning. Low was 58 and currently 60.

[cloudy72]

So trying to learn more about severe wx and tornado outbreak signals....saw in another weather forum where MJO in Phase 2 can be a good signal for tornado outbreaks (given the proper dynamics of course). Is this true? I checked the latest MJO and sure enough we are in Phase 2 now.

[tron777]

So trying to learn more about severe wx and tornado outbreak signals....saw in another weather forum where MJO in Phase 2 can be a good signal for tornado outbreaks (given the proper dynamics of course). Is this true? I checked the latest MJO and sure enough we are in Phase 2 now.

I have read that also. In combination with a La Nina, severe wx outbreaks including tornadoes are more favorable when we are in the MJO Phase 2. Now, that does not mean the OV is more favorable, the United States in general is.

[tron777]

61 / 49 at CVG currently with a stiff S wind.

EDIT: Sun is coming out now so the temps should start soaring.

[tron777]

12Z NAM has the warm front coming thru with rain / storms around midday tomorrow. then a break, then the convection comes thru with the cold front tomorrow evening. Sounding as of 8pm at CVG. Could be the NAM overdoing it of course.

nam_2021032400_048_38.98--84.69.png

[tron777]

12Z GFS is still going with more clouds and rain tomorrow so a reduced severe threat due to lack of instability. Strong winds of course in the evening and overnight, because we're dealing with a potent cold front and strong low to our west. The severe threat tomorrow evening will boil down to a break Thurs afternoon or no break as far as clouds / rainfall is concerned.