Dan The Weather Man: Talking Climate and Weather

 Oh She Trouble...    Ahhh.. Yes, the good old fashioned severe weather season has returned. After a rather quiet April, it seems Mother Nature needs to remind folks who's boss as she takes aim at the Midwest and MidAtlantic today, tomorrow, and on Saturday. In particular, its looking like tomorrow may bring her worst as parts of Kentucky, Tennessee, Illinois, and Indiana and others prepare for damaging winds, large hail, and tornadoes. The Storm Prediction Center (SPC) has outlined these areas in a Moderate Risk (Level 4/5) for the possibility of widespread, long lived severe weather with portions of the MidAtlantic (including Virginia) being outlined in a Slight Risk (Level 2/5).  SPC Day 2 Categorical Risk. Severe Weather is most likely over the Moderate Risk area, which encompasses Missouri, Illinois, and Kentucky  The Setup:  A potent shortwave trough and occluding, strong low pressure will slowly eject over the Plains and upper midwest over the next 4...

           We've all heard our friends, family, and even meteorologists discuss how "heavy" the air feels during humid summertime afternoons in RVA. How many of us have also jokingly said that we could "wear the air" on those particular days? Well I hate to burst your bubble....but you've been lied to...  warm, humid air is actually less dense or "lighter" than drier air. How can that be?! Well...           This is due simply to the presence of water vapor, which has a smaller molecular mass by particle than the same particle of dry air. This can be explained by a simplified example: Let's assume for a moment that dry air is only composed of pure oxygen molecules (O2). O2 has a  molecular weight  of ~32 amu (16x2). Water vapor, H2O, is composed of 2 Hydrogen molecules and 1 Oxygen molecule for a total amu of ~18 ((2x1)+16=18 amu). But what about Nitrogen (N2), which makes up around 78% of the  atmospher...

           With the warmer temperatures and severe weather season well underway, you may have heard me or other meteorologists mention the term "Inverted-V."  Unless you happen to be a weather geek like me or decided to google it after reading this, you've probably thought to yourself "is he talking about a mega wedgie"?            No I swear, the Inverted-V isn't another name for a wedgie...it is another way meteorologists describe an atmosphere that features relatively drier air near the surface. More specifically, the name originates from weather soundings that feature larger temperature-dewpoint (dewpoint depressions) spreads near the surface compared to the atmosphere, which resembles an inverted-v shape.  An Inverted-V Weather Sounding (Depiction of Atmospheric Conditions) Courtesy Of  wasatchweatherweenies . Red line is temperature and green line is dewpoint. As seen in the sounding, the red and gree...

          Last week, the arrival of a powerful, complex storm system into the Midwest and deep south created a widespread 3-day outbreak, with anticipation building that Saturday (March 15) would be the not so pleasant blockbuster day.  A rare "High Risk" severe weather category was issued by the Storm Prediction Center (SPC), indicating the usually high confidence in a large, devastating outbreak of severe weather. Unfortunately, many strong and fatal tornadoes occurred both during the evening on Friday and on Saturday, with well more than 150 tornado reports across the midwest and deep south. While the event was certainly impactful and many lives were lost, the forecasted environmental parameters suggested something even worse.  SPC Filtered Storm Reports for March 15. Particularly hardest hit was a corridor from southern Mississippi to west-central/central Alabama south of Birmingham           Before going any furt...

Time to Make Dorothy Fly...      Get Dorothy ready, she's going to be flying this week as the Midwest, Southeast, and East Coast prepare for a multi-day severe weather outbreak this weekend. Several tornadoes possible, including a few strong ones possibly on Saturday with widespread damaging winds in excess of 70 mph and large hail expected. A powerful surface low in association with a mid-level shortwave tough will provide the initial setup, followed by another mid-upper level trough leading to a secondary surface low development in the southeast on Saturday, giving rise to a multi-day and multi-state outbreak. Here's how we expect things to shake out as it stands now.  SPC Day 2 Categorical Risk. A "Moderate Risk" (Level 4/5) was issued for portions of Illinois, Missouri, Tennessee, and Kentucky for widespread damaging winds, hail, and tornadoes SPC Day 3 Categorical Risk. A "Moderate Risk" was also issued for portions of Mississippi, Alabama, and Louisian...

          Seems like severe weather season has awakened as Central Virginia is expected to see its first significant round of severe weather tomorrow afternoon. A very powerful storm system will sweep east tomorrow, bringing the chance for some damaging winds and a few tornadoes . The Storm Prediction Center has most of Virginia in a level (2/5) "Slight" risk area while the Tri-cities and points south are in an elevated "Enhanced" Risk area (level 3/5). Peak timing for metro RVA looks to be anytime between Noon and 2 PM .  SPC Day 2 Categorical Risk. Most of Virginia is outlined in a "Slight" risk while southern Virginia is outlined in an "Enhanced" risk area.          As of this evening, a very powerful mid and upper level trough with a deepening surface low pressure is centered over the midwest, bringing strong winds and isolated tornadoes. This low pressure system will deepen some more tonight and track near the Great L...