Updates below (most recent 11:00am)
Anyone out there have a WSAZ Umbrella? (We've been giving them away during the news-shows all month long...only a little time left!)
Today's weather map finally features the influence of the cold front that's been slowly plodding in from our west. The only problem is, the front is going to dissipate and wash right out. Then why/how will we keep up with the showers? Believe it or not, most of the weather at the surface ends up being a reflection of what's going on in the middle layers of the atmosphere more than the ground level. Here are some maps that will bear this out (explanation to follow):
|WRF - Vorticity - Tuesday PM||WRF - Vorticity - Wednesday PM||WRF - Vorticity - Thursday PM|
|WRF - Rainfall - Tuesday PM||WRF - Rainfall - Wednesday PM||WRF - Vorticity - Thursday PM|
I know some of y'all don't like the "Vorticity Talk" too much, but it really is what's at the root of the issue here. The top row of maps depict the middle level of the atmosphere, and what we're seeing is a gradual "cutting off" of a low pressure system up there. Normally storms simply follow the prevailing steering currents (indicated by the packed black lines), but whenever one swirls out and cuts off from the main flow they tend to move very slowly if at all. Think of it like an eddy that slowly meanders in the river after you have shoved an oar into the water. On the models, this 'cut-off' low-pressure system will barely have any reflection at the surface level, but will generate and instigate shower development. These showers themselves will have little momentum, so they can hang around the same places for a while too. Thus, we will have to keep an eye on them in case a prolonged downpour indeed sparks local street flooding-- but as described yesterday other forms of 'severe' weather will be minimal to non-existent.
Here's a rendition of the current rainfall expectations:
|HAS Precipitation Forecast||HPC Precipitation Forecast|
Typically, it's the yellows on the map that will up the antennae for localized downpours. Following the departure of these rain showers on Thursday, we will get to the summertime warmth we talked about yesterday. Temperatures still look to take on the 90-degree mark for consecutive days toward the Memorial Day weekend.
---Tangent (Tropical Storm Alberto)---
Tropical weather is a side interest of mine, having been in six land-falling hurricanes (all on purpose). It really is a fun/thrilling time if you're interested in experiencing certain aspects of life and nature ;-) Anyway, here's the latest on Alberto As of 11pm Monday, Alberto has weakened to a Tropical Depression):
|NHC - Tropical Depression Alberto - Track||NHC - Tropical Depression Alberto - Wind Field|
Our first storm of the season had flirted with serving as a conduit for channeling annoying showers inland toward the Appalachians, but instead will simply pass harmlessly out to sea as a minimal storm. The US coastline now has a more than 1200-day streak without a landfalling hurricane of Major (Cat 3+) intensity. It's the longest streak in modern history. Did I just jinx some part of the country? ;-)
Update (10:30am) - The National Weather Service's most recent advisory has indicated that "Alberto" has gone extra-tropical (which means it's turned into a more ordinary low-pressure system and is no longer tropical in nature). As such, this will be the last advisory on "Alberto". It was fun while it lasted!
Update (11:00am) - The National Weather Service has issued a Flash Flood Watch for parts of the area (see below) through 10:00pm tonight. It actually isn't supposed to go into effect until Noon, but often times they release the fact that there's going to be a watch well ahead of time. The threat, as expected, will be the slow-moving nature of any storm that does pop up causing downpours to become concentrated. Localized flooding can result, so this is something to keep tabs on through the day.
|Regional Radar/Satellite with Warnings Tracking||
From the Storm Prediction Center (below): Click For a Larger Image
|Activity Overview||Storm Outlook||Watches||Potential Watches||Storm Reports|
|Temperatures||HD Doppler Radar||Estimated Rainfall||Active Warnings|
|Click For Larger||Click For Interactive Radar||Click For Larger||Click For Larger|
Have a great day everyone!