Today has been a rainy, chilly, cloudy, stay-at-home kind of day in which the temperature remained almost steady for much of the day. The morning raob, also known as the upper air sounding, showed a significant layer of northeasterly flow from the surface up to about 800 millibars or 6,000 feet. This northeasterly flow pattern came about because of a large and strong high pressure system (1043 millibars) centered over central Canada with the ridge nosing down across the Ohio Valley into South Carolina. This high set up a wedge-like pattern with cool air flowing toward the southwest along the eastern side of the Apalachian Mountains. But this is not the pattern I think of when I think of a wedge which typically involves a high pressure center over Pennsylvania/New York area. While not a classic wedge, it sure produced results much like a wedge.
But on the BMX sounding this evening, that 6,000-foot layer of flow out of the northeast is gone. There still remains a shallow layer of east-northeast wind to maybe a 1,000 feet, but above that the northeasterly flow has been replaced by a west to southwest flow. So the modification of the atmosphere to set the stage for the possibility of severe weather Monday afternoon and evening has already begun.
Now, I still have some doubts about just how much the atmosphere over Central Alabama can recover. Surface dewpoints remain in the 40s with some readings still in the 30s across the Tennessee Valley. But along the Gulf coast, we're already seeing upper 50s along the Florida Panhandle with low and mid 60s in southern Louisiana.
The NAM model numbers seem to be more agressive than the GFS with dewpoints into the lower 60s Monday afternoon, an LI of -2.3, and CAPEs around 500. Not stellar values, but values that could be just enough for some severe weather action. And the numbers from Meridian are even better, so it could be a very close call.
Like most meteorologists, I want more data. So I'll have to be patient for the next model run and the next sounding to see how much more change the atmosphere will undergo. I'll while away the time by polishing the crystal ball - or petting the dog.
Radar continued to show a band of light to moderate rain from an east-west line just north of Birmingham to another east-west line at Montgomery. From my earlier post, the band of rain has slowly drifted southward. And temperatures have been quite chilly. My air temperature has been hovering around 44 degrees for almost 6 hours today. Dewpoint temperature has come up to 40 degrees. Temperatures are about 8 degrees warmer north and south of the rain band with 70-degree readings along the coast.
Meanwhile, a lone tornado warning was in effect for two counties in the San Angelo, Texas, county warning area - Schleicher and Crockett counties. Spotters were reporting a strongly rotating cloud with the storm, and the radar presentation was quite impressive. Reflectivity values were at the top of the scale, so there is also a strong possibility there is large hail with that storm, too.
Flash flood warnings were in effect for heavy rains in and around the Dallas-Fort Worth Metroplex. And slightly further north in Colorado, Kansas, Nebraska, South Dakota, and Missouri, winter storm warnings were in effect for tonight. And there was a string of winter storm watches eastward across Missouri, Illinois, Indiana, and Ohio. So that strong storm system coming out of the Southern Rockies was wreaking havoc with a lot of territory.
A warm front appeared to stretch just offshore along the Gulf Coast with 60-degree dewpoints in southern Louisiana. Gulf coast region had seen some breaks in the clouds today with temperatures running around 70 in many coastal locations.
We'll be watching this storm system and especially the movement of the warm front to see what impact it will have for Central Alabama tomorrow.
Temperatures remained on the chilly side with readings in the mid 40s to lower 50s. South Alabama was in the lower 60s and a few coastal stations had reached 70.
The latest Storm Prediction Center outlook for Monday and Monday night still places all of Alabama with the exception of the northeast corner in a slight risk area. Dewpoint temperatures have climbed somewhat this morning, but we're still a long way from dewpoints in the 60s. Challenging situation to forecast because it seems difficult to believe the atmosphere can modify enough in the next 24 to 36 hours to become favorable for severe weather. So our watchful eyes will continue to monitor changes and bring you our latest thinking as the next couple of days unfold.
I've recorded a tenth of an inch at my house in Shelby County. But this is the kind of weather my dog, Dakota, hates. She's very finicky and just hates to get her paws wet, so it's tough getting her to go out on rainy days. So it means I have to get wet to motivate her. You know who the boss is here!
An overrunning pattern continued this morning across much of the Southeast US with a good northeast surface flow with moisture riding up and over the cool air. Much of the rain was occurring this morning across the northern third of Alabama but a number of rainy periods are expected today and tonight and into early Monday.
It's interesting to note that the dewpoint temperatures were in the upper 20s to lower 30s, so the atmosphere is going to have to get cracking to recover enough for severe weather Monday. No sign on the morning surface chart of the warm front that we expect to move northward tomorrow. But as we all know from experience, the atmosphere can do some rapid changing. I'm still not sure that the slight risk area from SPC is correct - it may be a little too far north. Severe weather does seem possible from south of the Birmingham area to the coast on Monday afternoon and evening. But the northward extent of severe weather will depend heavily on how much the surface dewpoints can recover. Model numbers are still marginal in the Birmingham area with lifted index of -2 or so and CAPEs around 750. So this is one to be watching to see how much sunshine we can get and how much dewpoint recovery we get on Monday. In the mean time, some periods of rain with some possible heavy rain overnight.
The surface low sweeps by on Tuesday but skies are likely to remain mostly cloudy with some linger rain in the wraparound pattern behind the low.
Northwesterly flow aloft with a couple of disturbances at mid week and the end of the week will keep us fairly cool with temperatures below normal. GFS was forecasting the 540 thickness liine to reach the Alabama-Florida line by Friday.
Off to church and ushering duties this morning. Hope you have a good Sunday. Be weather conscious on Monday with the possibility of severe weather.