Joe’s Weather Blog: It’s about to get very wet out there (SUN-5/15)

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Good afternoon..pretty day out there after, for some at least, a frosty start. Frost was reported in Richmond, Independence, Harrisonville and I’m sure other places as well. The “official” low this morning was a cold 39°. St Joseph dropped to 37°…more on the lows this morning in the discussion part of the blog.

Forecast:

Tonight: Increasing clouds with a chance of some showers developing after 10PM…but especially towards 12AM from KC westwards. Lows in the 40s

Monday: Looks rather unpleasant. Rain off and on through the day. Steady and chilly temperatures for mid-May. Highs 50-55°

Tuesday: Rain likely. It may be a bit heavier as well…highs may stay in the 50s if we have rain into the afternoon. The AM especially looks wet.

Discussion:

I hope all of you are doing your outdoor things today as it’s a beautiful afternoon out there. The morning sure started cold though for mid-May as readings feel into the 30s to around 40°

Other area lows were a few degrees colder!

Capture

AM lows Sunday 5/15. Hamilton MO dropped to 33°!

So a chilly start as expected!

Now onto the rain.

Everything is coming together for a drawn out off and on rain on Monday. While the rain will not be that hard it will be rather persistent into the afternoon. Rainfall amounts should be under 1″ on Monday

The issues for Monday and Tuesday revolve around a series of waves that will be spinning around an upper level storm in the western part of the country.

Here is a look at the water vapor loop…showing the spinning storm out west.

 

I’m not sure any of the models are handling the situation for TUE that well at this point…but for reference…here is a look at the 500 mb maps off the NAM model.

Look for the areas of RED…that represents waves in the atmosphere that come this way through the Plains. Ahead of the wave there is rising air…behind the wave there is sinking air. Notice as well the “momma” storm lags back in the SW part of the USA…that will come out towards the end of the week. With us in SW flow aloft…these waves will move through through Tuesday. If you remember yesterday I referred to another wave in the northern stream. I sort of looked like it would come through and shunt the heaviest rainfall to the south of KC…well today’s data isn’t as bullish on that potential. As a result there was a slight northward shift in the heavier rain shield towards the I-70 corridor area.

gfs_tprecip_kc_15

GFS forecast through Wednesday evening

The NAM model in particular shows this….I think it’s overblown however and won’t show this on the air…should this model be more correct (and it has a ton of rain here on Tuesday) we’d have flooding issues.

nam_total_precip_kc_29

NAM model through 7PM Wednesday

The models do show lessor amounts across northern MO and that seems reasonable…it’s a matter of what happens from KC southwards.

The NAM model above though is on the higher side of the data. Here is a look at the various different model runs with different initializations and equations. We call these ensemble runs…and I want you to look at 2 things…1) the range. Going from about 1/4″ to over 5″…the other is the more dark solid line…that is the mean and is a good place to start to get an idea about the rain forecast.

Capture

Ensembles of the NAM model from Sunday AM

I’ve removed the highest total and the lowest total…and we come up with about 1.5″ of rainfall…which is a bit more than my initial thinking. Odds are I’ll be increasing my rainfall forecast to 3/4″-1 3/4″ of rain as an average in the area over the next 2 days or so. IF I remove a few more of the extreme highs and lows…the average comes down to about 1.3″ or so…

The key to the whole event may be the rain on Tuesday. The model data shows a rather stout wave coming in to the region. Should this verify…the rain amounts will be on the high side of my forecast…or above. Actually IF this was during the winter season…this would have heavy snow/ice written all over it potentially…with a cold NE wind…surface low to the south of the area…850 mb low (the low above the surface) taking a rather favorable track for heavy precipitaiton…alas it’s the May version of a winter storm.

My feeling is the heaviest wave on Tuesday is being overdone…and I think we start to see drier weather Tuesday afternoon. this should keep rain totals under 2″ through Tuesday night I think. There may be a bit more though down towards the US 50 corridor region. This would be great news for the dry areas between US 50 the Lake of the Ozarks region as I wrote about yesterday. Sedalia is running almost 8″ below average for the year so far.

We should be dry on Wednesday into Thursday. Although by Thursday night as the “momma” storm kicks out…our rain chances may be on the increase again. it doesn’t look like a lot of rain though for the end of the week.

With all this happening and the cooler than average temperatures…severe weather is not expected in the region this coming week. At this point the earlier next severe weather chance may be either later next weekend or into the week of the 23rd.

The bottom line…

Joe

 

 

 

 

 

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