One of the interesting challenges in the field of meteorology is forecasting. It's the modern day equivalent of soothsayers, prophets, and fortune tellers all rolled into one! But it is also based on science dealing with the changes to the fluid we call air which makes up the atmosphere of the planet, an atmosphere that sustains life for all living things.
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still remains a shallow layer of east-northeast wind to maybe a 1,000 feet, but above that the northeasterly flow has been replaced by a west to southwest flow.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.
-Brian-
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.
-Brian-
on March 19, 2006, 9:27 pm
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