Saturday, February 25, 2023

Active Weather Pattern This Week

(Forecast)

Sunday (High 71, Low 53): Some lingering fog possible in the morning, then partly cloudy. Becoming breezy with increasing clouds in the evening and night hours. 

Monday (High 72, Low 59): Windy and rainy. Isolated thunderstorms are possible and could produce strong, gusty winds. 

Tuesday (High 76, Low 48): Sunny. Cool in the morning, mild during the day.

(Extended Outlook)

Wednesday (High 75, Low 54): Increasing clouds with a 20% chance of showers/thunderstorms.

Thursday (High 72, Low 60): Thunderstorms likely - some possibly strong. 

Friday (High 61, Low 50): Showers likely - lingering storms possible. 

Saturday (High 58, Low 37): Mostly sunny and breezy.

(Notes)

It is a good time to review severe weather safety.

Next SKYWARN class is 6 PM Wednesday March 8th at Trinity Town Hall in Morgan County. There are also online classes available. These are free, by the way, in case you've never taken one. Anyone with an interest in weather or public safety is encouraged to take a class. 

And I think everyone in the weather community should extend congratulations to Ms. Elizabeth Leitman, who within the past couple weeks, became the first female forecaster at the Storm Prediction Center to issue a severe weather watch. She was on a recent episode of Weatherbrains

(Discussion)

It was an overcast and often foggy day with periods of light rain in the Tennessee Valley. The High in Cullman was 59 with a Low (so far) of 52. Winds were variable today, and it got breezy at times, but the wind has calmed down now. Visibility is only at 8 miles, not so much fog now, but overcast, sort of a raw day. Current temperature is 55 degrees, same as dewpoint, making relative humidity 100%. Pressure is 30.21 inches and steady. Visibility is down to 3 miles in Jasper with the fog, and they are at 59 degrees, saw a High of 64 today. Visibility is down to 4 miles in Haleyville with fog and mist, light Southwest winds. They are at 54 degrees and only saw a High of 57 today. 

Elsewhere around the region, Fort Payne has light rain and fog, 57 degrees, visibility down to 4 miles. It is raining in Huntsville with visibility of 7 miles, temperature of 52. Up in Winchester, fog/mist and 50 degrees, visibility reduced to 4 miles. Fayetteville overcast and 50 degrees but with better visibility of 9 miles. The fog has broken up there within the last hour. 

I wrote the above an hour or two ago and then got delayed by computer glitches and problems in trying to cook in a crock-pot and a more immediate meal on a regular stove. It seems I collected observations about 5 PM, and it is about 7 PM now. Moving right along . . .


That front is stalled out around Montgomery. And you can see another front out there in California ahead of a strong Low pressure system back over the Pacific making its way into the coast. 


Most of the country is getting a break from the rain or snow, with High pressure dominating. But you can see where there is a wintry mix out in California into parts of the Desert Southwest and back up into the Pacific Northwest. And of course there are a few pockets of rain like around here. 



Tomorrow the ridge of high pressure around here will provide us a break from the rain. We may still have some fog in the morning. 


The NAM is showing a little more moisture available tomorrow, but I'm skeptical. If there is, looks to be over Tennessee. Doubt it is enough for even isolated rain, probably have partly to mostly cloudy skies tomorrow. Clouds definitely increasing tomorrow night and winds picking up. But during the day tomorrow, looks like a mix of sun and clouds, a High of 70 or so, Low in lower 50's, about 53. 



That cold front coming from West of the Rockies should bring the Great Plains an organized severe weather threat tomorrow. The main threat is widespread damaging thunderstorm winds. Especially over Oklahoma, looks like some of these storms could become especially damaging. 



There is also a risk for severe hail over a large area, but the tornado threat looks more like a basic isolated tornado threat and may stay confined to mostly Oklahoma and Southern Kansas. 



The core of that system is moving well to our North on Monday, but we do have a trailing line of showers, maybe some storms, around here. 



The severe weather potential looks to stay up in Northeast Tennessee and up into Kentucky with this one. 


The NAM does show some instability and wind shear getting together in the afternoon. But keep in mind, we don't have a great lifting mechanism to go with it since the Low is going so far North. If anything did go severe, would probably be right ahead of the cold front itself. 



Even if you look back across the Mississippi border, the instability is just barely enough to work with for a storm becoming severe and producing some damaging winds, maybe some hail. Take a forecast sounding near Decatur, the chance of severe looks just about nil. 

So can't totally rule out an isolated stronger storm, but for the most part, this looks like a rainy and windy day with barely enough instability for thunderstorms. Despite how organized things may get in the Plains tomorrow, Monday does not look like a big deal for most of us around here, if for any of us. 

Looks like a High about 72-73, Low about 58-59, windy day, plenty of rain, maybe an isolated thunderstorm or two. Severe thunderstorms are not likely around here. 



Then Tuesday looks sunny, a break in the action, High in the mid-70's and a Low dipping back into the upper 40's with good radiational cooling overnight, looks like that front will move through at a good clip.



Clouds should increase some on Wednesday, but I think rain chances stay minimal. Will see similar temperatures but the Low rebounding up into lower 50's as more moisture comes back into the region. Wednesday night does look wet, but overall I think the day stays dry. 



On Thursday our next front moves in here. Showers and thunderstorms are likely. High should be near 70, Low near 60. 



The GFS has come more into line with what the ECMWF has been showing as far as this system moving out of the area by Friday afternoon or evening. In fact it is now faster than the ECMWF, where before, it was slower. (Unusual for the GFS to move a system slower like that.) Frankly the GFS and ECMWF have not been too consistent from run to run sometimes over the past few days about this, and this is still five and six days away, this storm system. 



Here's the ECMWF look for 18Z Thursday and Friday - 18Z translates to Noon when we're on Standard time. 




The GFS shows enough instability and wind shear overnight between Thursday and Friday to support some severe weather around here. Of course this is just general guidance since this and the European model still have yet to show a lot of consistency with the details of timing/placement of this system. 


Even where the EHI maxes out though around Moulton in the wee hours of Friday morning, this looks like just barely enough unstable air to combine with some really strong wind shear, to support a threat for mainly damaging winds, also isolated tornadoes. 

The Storm Prediction Center has not issued an official outlook area yet because of how unclear the guidance is. Once we get done with Monday's system, we'll probably have a pretty clear idea of what the potential will be with this next one. 

Looking at analogs and the overall pattern, thinking back to my personal experience, this is the sort of setup where we could have a lower-end potential for strong storms, or a more organized threat for severe weather. Will have to keep an eye on the mesoscale details. For now it looks like if we do have severe weather, it will probably come on Thursday night or Friday, less likely to start early on Thursday. 

And now as I'm looking at temperature guidance, the High for Friday should be lower 60's, Low down near 50 again. So maybe I should adjust that to say Thursday evening through the overnight. For the severe threat. Some of it could last into early Friday morning, but with this timing of the system, looks more like a cool rain lingering as we go through the day. 



High pressure quickly moves back in for Saturday of next week, and we will probably still be breezy behind this front. Should be mostly sunny with a High in upper 50's, Low in upper 30's. 


Then for this whole period, the next week, looks like our rainfall totals will average about 2-3 inches. Obviously in heavier showers or any storms that become severe, locally heavier amounts are possible. And overall it looks like more of a soaking for Tennessee than Alabama counties. But all of us have a decent chance at plenty of rain this week. 

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