Afternoon Sleet? Yes. Sleet. (Not Hail)

@Klappermom is the latest #tSpotter hero. She sent in this linked video, which for whatever reason we can’t embed, so here it is (http://www.mobypicture.com/user/klappermom/view/15059695). Turn up the sound!

Why’d it sleet this afternoon when it was 50 degrees at the surface?  Keep in mind that it’s almost always colder the further up in the sky you go, and that’s what the precip is falling through on its way to you on the ground. When it’s really cold up there, the precip may go from snow, to sleet, and then to rain.

This graphic helps illustrate the point, even though it’s not exactly our situation.

What’s happening today is that the air near the ground is very dry. When the precip falls toward the ground, some of it evaporates. That process cools the air around it, lowering the temp for the precip that doesn’t evaporate, causing the sleet.

Hail happens as a result of usually warm weather convective thunderstorms with a strong updrafts and downdrafts. Rain tries to fall to the ground, but the updraft winds keep it suspended in the cold air aloft. The longer it’s suspended, the bigger the hailstones get, until they get so big they fall, or they’re transported to the downdraft part of the storm and fall to the ground. Science!

Wet Thursday, Beautiful Weekend

Expect sun & clouds Tuesday and Wednesday, then the skies open Thursday. The below map from NOAA’s Weather Prediction Center dumps less than a half inch on us …

fill_99qwbg… but during the NWS media conference call this morning, the NWS said they think totals will be closer to an inch.

Friday the rain slowly clears out, paving way for a glorious weekend in the low 70s. Rain is not expected.  Great news for the Will Power 5K in Franklin (Saturday 7:30am). You can sign up for that here: http://www.signupWP5K.com 

The Week Ahead - Unseasonably Cool

First, there’s a Dense Fog Advisory until Monday at 9am.

THE WEEK AHEAD

No complaints tomorrow – Monday’s high temp is 60, and we look like we are done with the rain.

Unseasonably cool temperatures return Tuesday. Morning wind chills Tuesday and Wednesday will be in the 30s. Tuesday’s high is only 50. Those high temps will slowly warm, but stay stuck in the 50s, through Friday.

We don’t expect rain until Thursday, lasting into Friday morning. According to NOAA’s Weather Prediction Center, a half inch of rain or more is forecast for Thursday & Friday:

The weekend looks nice – temps in the 60s, maybe even the low 70s, and although it’s too soon to say, we don’t anticipate any rain.

Here’s the NWS Planner for all of Middle TN:

We are in the middle of severe weather season, yet thankfully stuck in a benign weather pattern. Here’s hoping this continues.

IN TWO WEEKS

Warmer than normal…

…and Wetter than normal:

The Rain Is Here. What About Easter Morning?

With a steady, light rain arriving, the next question is: what about the morning?

Our NWS says there’s a “chance” of rain.  I asked three models what they thought. Their opinions:

1.     HRRR says the rain will be gone by 3am:

HRRR 3am

2.     The RAP agrees. Rain free by 6am in the morning:

RAP 6am

3.     The Euro agrees. Things look dry at 7am.

Euro 7am

However, note (a) these are models and may be wrong, and (b) all three models predict morning rain in the Memphis area, which may arrive here by mid-to-late morning.

The good news is that the NWS, and the models, move the rain out by mid to late afternoon tomorrow.

 

Today’s Late Afternoon Rain/T’Storm ETAs

Our two short term weather models (HRRRand RAP) think rain will arrive before dark. The rain is coming from the SW (around Memphis) and will move NE. Don’t bet anything on the timing (models are often off by hours), just know the timing in these models are decent indicators of what’s to come.

Bottom Line: Rain is likely before dark. Here are the details:

HRRR

At 3pm today, the HRRR has the rain in W Williamson Co:

By 4pm, the HRRR has Davidson & Williamson Co wet:

RAP

The RAP sends the rain in about an hour later. At 4pm, the rain is in W Williamson Co:

By 5pm, the RAP delivers rain to everyone S of I-40:

And by 6pm, everyone’s wet:

A few thunderstorms may be mixed in as the rain continues into the early morning hours Sunday. Very light, off/on rain showers are expected Sunday morning.

 

Wet Easter Weekend

Saturday

Our NWS forecasts no rain tomorrow morning, a chance of rain between 1pm and 7pm, and after that, yes, it’s going to rain until around 4am Sunday morning, perhaps even longer than that.

A quick look at two models illustrates the rain’s arrival.

The American GFS model at 4pm Saturday shows the arriving rain:

The European model agrees. Here we are at 7pm.

EuroSatu

Our NWS forecasts rain in the wee hours Sunday morning. Rain may continue during daylight hours, but chances will generally decrease throughout the day.

The GFS forecasts light rain Easter morning until around 1pm. The European model keeps it around longer, through most of the afternoon.

Bottom Line

Saturday night and Sunday morning Easter Egg hunts are forecast to be rained out. Outdoor Easter morning sunrise services wil have to deal with close to a 1/2″ of rain already on the ground, and perhaps more falling. Plan to move services indoors.

I’ll put out another update tomorrow.

It’ll Probably Rain Easter Morning

Yesterday’s weather models suggested rain Easter morning. Today’s models are saying the same thing:

Here’s what the European model looks like for us at 7AM Sunday morning. The rain is pink on this image:

Euro7am_001

The American GFS model at 7am Sunday morning shows rain:

The Short Range Ensemble Forecast model also has it raining here Sunday morning at 7AM:

Here’s NOAA’s take on rainfall from 1AM to 7AM Sunday morning:

Finally, our NWS says rain is “likely” Easter morning. There may even be a chance of thunderstorms.

Have a Plan B if you’re planning on being outside Sunday morning.

Easter Morning Forecast - Rain?

Some of you are hoping to have outdoor services celebrating Jesus’ resurrection. Others may be planning to wear fancy clothes and hide eggs outside Sunday morning. Many of you will be doing both.

There is a chance of rain Sunday morning. Below is what the models say, but first, note: these are only models. They change all the time, and sometimes they’re wrong. So, the point of this post is to let you know rain may be an issue, and if you have plans outdoors Sunday morning, you may need a Plan B.

One model rains us out Easter Sunday morning, the other doesn’t.

The GFS (Global Forecast System) is an American model. When it does well, people say it’s as good as the European model. When it does poorly, they call it the OooFuS.

Anyway, the GFS says it’ll rain Friday and again Saturday. On Sunday morning, rain is approaching.

Sunday 10AM –

Sunday at 10am. Rain moving toward us.

Then by 1PM Sunday, it’s raining –

I like to think we beat Europe at lots of things. But, a strong argument can be made their weather model is better than ours. It says it’ll rain while we sleep Sunday morning. Here’s that model at 7AM (the map, zoomed in on Tennessee, isn’t that good), which says it’s still raining:

euro 6am

At 10AM it’s still raining, but the rain is on its way out –

euro 10am

I’d have a Plan B.

 

 

Snow While You Sleep - What the Models Think

There are two main short-range wx models: the RAP (Rapid Refresh) and HRRR (High Resolution Rapid Refresh). These are models, not forecasts, and can be wrong. Below are middle-of-the-night & morning rush hour snap shots of how much snow the models will think will fall in a one hour period.

By the way, normal temps for March 25 are highs of 64, lows of 41.

Midnight

RAP

HRRR

3:00 am 

RAP

HRRR

7:00 am

RAP

HRRR

 

Updated Snow Forecast 0.25″-0.50″

Here’s the NWS Graphic for snowfall accumulations overnight.

image5