SLICING IT THIN...
- 7 days ago
- 3 min read
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TO RAIN OR NOT TO RAIN, THAT IS THE QUESTION?
The big topic of discussion lately is a weather pattern that has the potential to be active and much wetter than in recent weeks. While that is certainly on the table, models are not doing us any favors through the weekend with precipitation output lower than I had hoped. No matter how favorable the pattern, individual storm tracks are always critical to where the more significant amounts end up falling.
One of the things that may end up hurting us some this week is the western trough splits, and the lack of phasing keeps it from re-loading as quickly or aggressively as guidance had indicated previously. You can see in the animation how the energy digs into the west and then splits with one lobe weakening as it lifts to our NW, and the other actually retrograding from Colorado to Baja Mexico. It actually backs up.
The end result is that the first 2 waves of rain Tuesday and Thursday remain heaviest to our south. The third wave Friday is more impactful, especially to the NW. Amounts here are generally light to perhaps moderate in a few spots. At least through the weekend, we'll be slicing it thin if things don't change, and that is still possible.
Again, we are in line for some much needed precipitation, but without knowing how much or how widespread convection ends up, leaves amounts very much in question. Here's what the EURO and GFS show for potential amounts through Sunday midday.
The EURO
The GFS
The national blend of models is significantly heavier so there are other sources showing heavier amounts. I have reservations about the higher totals the NBM is promoting.
Short term, the disturbances that come through Tuesday and again Thursday are far from dynamic but they do introduce some moisture into the pattern that really blossoms by Friday. Notice too, how temperatures increase as the moisture goes up. After a grungy cool day Tuesday, readings by Friday may reach 70+ in the south. The EURO shows this for temperatures the next 2 weeks in the Quad Cities.
Here's the 7-day temperature departures for the period March 4th through the 11th.
As you can see, temperatures locally average above normal by 15-16 degrees daily.
Friday, available water vapor is expected to be well over an inch, that's about 600% higher that what was seen over the past weekend. Big improvement and the reason we finally have a crack at some precipitation. In fact, dew points Friday could be pushing 60 in the south. Combine that with highs of 66 to 74, and it should feel on the muggy side for the first time this year.
The combination of warmth and moisture brings CAPE (Instability) to much of the central U.S. Friday. Depending on how forcing comes together, thunderstorms are likely in some parts of the central Midwest Friday.
SPC actually shows a slight risk of severe storms as far north as southern Iowa. That's a fairly high risk 4 days out this early in the year.
One of the things I do find encouraging is that at least through mid-March the models are showing the western trough consolidating (or phasing). If indeed this happens with that big ridge over the east, the table is set for an active storm track here in the Midwest. It's possible a fairly impressive storm could come out of the set-up shown below. That said, it is highly dependent on the phasing that's indicated below. It's been hard to come by this year.
That keeps us mild into the 14th or so, but what happens after that has me concerned. The MJO is showing a move to phase 7 which in March is a cold phase. Models haven't really locked in on that yet. I think there is a real strong chance of a wintry pattern returning around March 15th..
Meantime, Tuesday overall looks to be dreary day with a bit of drizzle or a few brief showers in the morning. Hopefully Wednesday night or Thursday we see something a bit more generous. I do think Friday is the day with the best rainfall prospects
By the way, I have a weather school planned for April 25th at the De Soto Hotel ballroom in Galena. The emphasis will be on numerical models, understanding and interpreting them to make your own forecasts. Click on the banner at the top for the agenda and details. Also, if you purchase a ticket you will be eligible for a free night for two, the night of the seminar at my AIRBNB. Anybody registered will be entered into a raffle that will be announced in the next 3 weeks. Check out the link to register at the top of the page for more information. Hope to see you and roll weather...TS
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