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Joe’s Weather Blog: Monday storm risk develops (SUN-3/5)

Another windy day in the area with gray skies and above average temperatures. It’s feels cooler out there though because of the lack if sunshine and I’m thinking these clouds aren’t going anywhere into Monday. A cold front will be moving through the region later Monday sweeping the clouds away and allowing for a brighter TUE>WED in the region. Overall the week will be mild again with another change in the temperatures possible on Saturday.

Forecast:

Tonight: cloudy with pretty steady temperatures. There may be a few drizzle patches developing in the AM. Lows in the 50s

Monday: Cloudy and windy. There should be some breaks in the clouds in the afternoon. Some areas of drizzle are also possible. Later in the day, between 4-8PM there may be some thunderstorms developing and moving through. There is a chance some of those storms could be strong>severe but depending on how warm we get. Highs in the 70° range. Winds S/SW 20-35 MPH. IF temperatures aren’t as warm…let’s say in the mid 60s then the chances of stronger storms are lower in KC proper

Tuesday: Sunny and pleasant…although rather breezy. Highs around 60-65°. West winds of 15-30 MPH

Discussion:

At this point the interesting weather days appear to be Monday afternoon and also potentially next Saturday. Let’s deal with the Monday situation.

The satellite picture this afternoon clearly shows a large swath of moisture that has moved into the region. This happened last night in the form of cloud cover and it’s going to be hanging around until a cold front comes through the area.

The strong south winds in the region, gusting to 35 MPH, will continue to drive the gulf moisture in the lower levels of the atmosphere towards the region.

In the animation above via windty.com you can see the flow of air coming from the south to the north. This will change tomorrow evening because of a cold front that will change the winds towards the west and sweep this moisture (and cloud cover) away from the area.

Since we’re into the month of March and since temperatures will be about 15° above average…and since the surface dew points will be well into the 50s as the are now…one wonders about the risk of storms later tomorrow and briefly tomorrow evening.

The surface map certainly shows the dew points (surface moisture) streaming northwards at this point…and these will continue to be in play Monday afternoon as the front gets into far NE KS and NW MO.

sfc

Note the red/purple circles towards OK and TX…that indicates lower cloud bases and/or some sort of combination of lower visibility.

capture

The purple circles represent LIFR rules and show the lowest cloud bases (under 500 feet up) and/or <1″ visibility. That can be because of fog or precipitation of some sort. The two dots next to each other in the weather stations report above indicate light rain. That is “deeper” moisture showing up and that too may try to come up towards us overnight into Monday…so as a result I can’t rule out some patches of mist/drizzle developing later tonight.

Now about the set up on Monday. By 6PM there is going to be a cold front towards the west of KC.

sfc

Ahead of the front…south wind of 30 MPH+ will continue to draw moisture northwards. Dew points should increase from near 50° today to 55+° Monday afternoon. Behind the cold front the air will be briefly cooler…but look closely into eastern CO. Notice the thin green lines (dew points) there…they plunge to -10° values. Indicative of VERY dry air that is created by air currents sweeping down the slopes of the Rockies and drying the atmosphere out. This is downsloping winds at their finest out there. If realized that represents a relative humidity of about 10%!

So for us…it’s a bit murkier. CAPE values, which help us find the higher instability will be from 1000-2000+ in the area. Not bad at all for early March.

The yellow areas above from near Lawrence southwards through SE KS show the max instability at 6PM tomorrow. So you have a cold front coming into the instability at roughly peak heating. Storms should form and fly towards the ENE at close to 50-60 MPH. Why so fast? Well the mid level winds (at roughly 10,000′ and above) are cranking away at 50+ knots (55 MPH+).

capture

We will also be somewhat capped for much of the day…so as the cap weakens later in the afternoon there should be some instability to work with as well for the storms.

When I see winds above us 50-60 MPH and there are storms developing and flying through, I’m always concerned about the potential of near severe to sever wind gusts of 60 MPH. IF the winds are cranking that fast above us…the convection is churning up this air…the rain is falling and the atmosphere is turning over in a sense. So it doesn’t take a lot of imagination for me to see how we could get some of these stronger winds to work down towards the surface.

Freezing levels also won’t be that high up. Roughly 11,000 feet above us…so it’s not out of the questio to think we could get some hail from these storms as well. The SPC does of parts of the region under a “slight” risk of severe storms for later Monday.

capture

This looks reasonable to me as the storms should form to the west and NW of KC and fly through the area. Let’s see how fast they can potentially strengthen to severe limits.

Rainfall wise…obviously all need some. Especially in the areas north of the storms from last Tuesday night. Fast storm motions may prevent abundant rainfall…but hopefully we can get upwards of 1/2″ or so in spots in the convection. Obviously when dealing with thunderstorms, you’re results will greatly vary from one community to another. Nature of the beast of thunderstorms.

Another note, while tornado formation is unlikely…there is a LOT of wind shear (speed shear) from the ground upwards to a few miles above us in the early evening in the region especially from KC eastwards. Could there be some sort of weird isolated spin-up? It’s worth monitoring just in case. In this case speed shear refers to the change in winds from the ground to another part of the atmosphere. The surface winds are forecast to be from the SW at 15-25 MPH while up at around 4500 feet the winds are forecast to be from the SW at 55-60 MPH. That’s a pretty decent increase in wind speeds and that creates shear. The winds aren’t changing direction that much and that is in our favor…but I still want to watch this tomorrow.

So there you have it. Be Weather Aware tomorrow afternoon for these storms. Our feature photo comes from Barbara Verganian showing the storms last Tuesday from her perspective in Greenwood, MO!

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Joe

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