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Mid-Morning Update on Rain, Dropping Temps.

Mid-Morning Update

I’m wondering if the HRRR (the best, but imperfect, short range weather model) is overstating rainfall totals.

The latest run of the HRRR says this is what our radar should look like at 9 a.m.:

But, here’s what the radar actually looked like at 9:09 a.m.:

Not much rain!

This suggests the HRRR is not “initializing” or “verifying” well. To say it another way, this means the model is predicting the weather based on an imperfect/incorrect assumption. When that happens, accuracy about the future is suspect.

The cold front has advanced east. It’s now on the east side of the Tennessee River (between Jackson & Nashville). Here’s the current location of the front:

The front is pulling the moisture out of Louisiana/Mississippi, shown below on water vapor imagery:

We don’t see any meaningful rain on the west side of the front. So, it’s all about when the front passes and clears us out.

It appears the HRRR thinks the cold front will slow/stall. By noon, HRRR redevelops the rain:

HRRR does not clear us out until 6 p.m.

If the front does not stall, and keeps moving east, it may shut off the rain much faster, and you may need your jacket earlier in the day. If the front stalls, expect showers to redevelop, possibly east of us.

My gut feeling: it won’t not rain as much as we thought. The front will clear us out. It’ll rain east of us this afternoon.

{End of mid-morning update}

Today – Rain – High 75

7a 71 . 10a 75 . 1p 75 . 4p 68 . 7p 60 . 10p 55

Unknown

The rain is has arrived ahead of an advancing cold front:

Most of the short range models predict a solid rain blob that keeps redeveloping all day, not moving out till late this afternoon/evening.

There should be small breaks in the rain here and there. We like to say the rain will be “off and on, but mostly ‘on’.”

Grab all your rain gear. You’ll need it.

Severe weather is not expected, although the SPC (Storm Prediction Center) gives us a 5% chance of damaging winds happening within 25 miles:

day1probotlk_1200_wind

So, how long will it rain?

The RAP model thinks the rain will be gone tonight by Sunday 7 PM:

rap_pr1_slp_t850_scentus_14Hi-Res NAM model agrees. Here it is Sunday at 7 PM:hires_ref_ky_19

Gusty winds at times may make it rain sideways, especially during heavier downpours.

WPC (Weather Prediction Center) Rainfall totals of 1′ through Monday 7 AM:

hpc_total_precip_tx_6

Our local NWS office thinks 1″ will be the minimum amount of rain. Some areas may see 2″ with locally heavy rainfall up to 3″.

We will reach our high of 75 this morning. Temps will continue to drop through out the day. A wind breaker and light jacket will be a smart idea after the rain moves out.

Monday – Fall – High 68

7a 50 . 10a 59 . 1p 65 . 4p 67 . 7p 62 . 10p 55

Fall returns. The cold front will deliver some of the coolest and driest air of the season.

Tuesday – Another Taste of Fall – High 72

7a 49 . 10a 61 . 1p 69 . 4p 71 . 7p 66 . 10p 59

Cool temps and dry air won’t be going anywhere. Light jackets in the morning can be discarded in the afternoon.

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