UPDATE: 12:45 p.m.: The National Weather Service has issued a Severe Thunderstorm Watch for all of Maryland except for lower Eastern Shore, effective until 8 p.m. Thursday. A Severe Thunderstorm Warning is in effect for Garrett County.

Also, the thermometer at BWI-Marshall reached 98 degrees at 1 p.m. today, matching the record for the date, last reported here in 1966. Earlier post resumes below.

Where shall I start? This year does seem to be shaping up as a Big Weather year for Baltimore and Central Maryland. Big Snow, Big Heat and - dare I say it - a big tropical weather season? It happened in 2003. Remember? The record snowfall in February, followed by Tropical Storm Isabel in September? 

We'll just have to wait and see. For now, we're dealing with our sixth straight day of 90-plus temperatures and high humidity. There is a Code Red Heat Alert in Baltimore again today (Thursday). The heat index numbers for this afternoon are expected to reach 104 degrees - just shy of Heat Advisory criteria. Heat Advisories are up for the southern Chesapeake, south of the Potomac River. And there's more to come.

Very old records continue to wobble and fall with this heat wave. Forecasters at the NWS service forecast office in Sterling, Va. say yesterday's high of 97 degrees at BWI tied the Baltimore record for the date, set in 1894. Today's forecast high of 96 degrees will threaten today's record high of 98 degrees, last reached on this date in 1966.

BWI-Marshall may also have broken the record for the warmest daily low for the date. The overnight low this morning at the airport was 79 degrees. If it doesn't get cooler than 76 before midnight, that will break the old record of 76, set in 1924. 

Some of us could see some thunderstorms this afternoon or this evening as a "cold" front (HAH!) pushes through. There is a potential for some of the storms to grow to "severe" proportions. There is some threat of hail, but damaging winds, especially between the Blue Ridge and I-95, are the main worry. The threat should end by midnight.

Friday is forecast to be the coolest day of the week, and the driest, with a predicted high of only 89 degrees after the passage of the cold front late today. But after that, the high behind the front slides off the coast and (this should sound familiar) we fall into the return flow around the clockwise-spinning high. And that brings us more hot, humid air out of the south or southwest.

(Today, winds are out of the west. That's also bad news, as air flowing downslope off the Appalachians is compressed, which heats it up even more. But I digress.)

With that south or southwesterly flow over the weekend, forecast highs climb back in to the 90s, with a high of 92 expected Saturday, rising to 94 on Sunday and falling back only to 92 on Monday.

There is some relief at the end of the 7-day forecast, finally. After more showers and storms with another cold front on Monday, forecasters say, we'll drop back to more seasonable, merciful temperatures on Tuesday and Wednesday, in the low- to mid-80s. 

Hey, it could be worse. We're finally out of the bad air zone. There is a Code Orange air pollution forecast up today for Washington, D.C. and its suburbs in Maryland and Virginia. But somehow the Baltimore region has escaped the smog with just "Moderate" air pollution expected through Friday.

(SUN PHOTO: Top: Kim Hairston, 2010/ Bottom: Barbara Haddock Taylor, 2008)