The autumnal equinox occurs Sunday, September 22, 2024 at 7:43 AM, but the days and nights are not considered equal until Saturday, September 26th. This is because of the atmospheric refraction of sunlight. When a wave encounters a medium whose density differs from that through which the wave has been propagating, conservation of momentum and energy … Read more
A hurricane is the exact same meteorological phenomenon as a typhoon. The difference is simply a function of the storm’s location relative to the International Date Line (180ºW). A “hurricane” west of the International Date Line (IDL) is called a typhoon. The term is believed to have its origins in Sinitic, one of the Chinese … Read more
On August 29, 2015, for the first time on record, three *major* hurricanes were active simultaneously in the central/eastern Pacific (east of the International Date Line, 180ºW). A major hurricane is defined as a category 3 or higher. Yet another record was set at 10 pm CDT. 8 pm CDT 8/29: Three Major Hurricanes Set … Read more
On this, the -year anniversary of Hurricane Katrina’s final landfall east of New Orleans, I wanted to share some graphics and the very rare, dire warning issued the National Weather Service in Slidell, Louisiana that likely saved many, many lives. Radar Loop at Landfall Satellite Loop at Landfall Location of the NWS Brief … Read more
Prior to the advent of weather satellites and aircraft reconnaissance of tropical cyclones during the mid-20th century, the loss of life due to unexpected, landfalling hurricanes was tremendous. In 2015, hurricane forecasting continues to improve thanks to ongoing upgrades in observational technology (aircraft, dropsondes, tail radar, etc.), computational resources, improved numerical prediction models (model resolution, … Read more
Summary & Forecast Verification [Thursday 8/20/15 8 pm] ***Today Among Our Coldest August Days on Record*** A few days ago, I predicted that our strongest cold front in 3 months would move through North Texas (below). The forecast worked out perfectly (and to the contrary of the armchair meteorologists who declared otherwise on the day … Read more
Trends In The Ratio Of Damage To Deaths Caused By United States Land-Falling Hurricanes 24th AMS Conference on Hurricanes and Tropical Meteorology (2000) Chris C. Robbins and James Gross National Hurricane Center, Miami, Florida We have estimated that, if the pre-reconnaissance trend continued at the time of Hurricane Andrew, approximately 4,354 deaths may have … Read more
A Climatology Of Rapidly Intensifying Tropical Cyclones In The North Atlantic Basin, 1975-2000 25th AMS Conference on Hurricanes and Tropical Meteorology (2002) Chris C. Robbins and Stacy R. Stewart National Hurricane Center, Miami, Florida 1. Introduction Rapidly intensifying tropical cyclones pose a significant forecast problem for operational meteorologists. Unfortunately, the climatological nature of such … Read more
I want to kick off this piece with a discussion of Tropical Depression Bill’s intensification over Missouri, hundreds of miles inland. ➡ Click here to skip to the North Texas impacts to see how much rain fell at DFW and what the peak winds were as Bill passed across the area. At 4 p.m. CDT Friday, … Read more
This post is a carryover from the previous post that contained three days worth of forecast updates leading up to the formation of Tropical Storm Bill. In an effort to improve readability, I thought it would be best to create a new post given that T. S. Bill will soon make landfall and subsequently move … Read more
Mesocyclone-Induced Downbursts Associated With The Landfall Of Hurricane Irene (1999) Over S. FL 24th AMS Conference on Hurricanes and Tropical Meteorology Stacy R. Stewart and Chris C. Robbins Tropical Prediction Center, Miami, Florida 1. Introduction This paper examines the occurrence of multiple damaging downbursts or “miniswirls” with the passage of Hurricane Irene across South … Read more
May 2015 was the wettest month ever recorded in the United States since record keeping began 121 years ago according to the National Climatic Data Center (NCDC). The main contributing factor to the nation’s “wettest-May” was the incredible rainfall totals across the Central United States. Meteorologist Chris Robbins posted that May 2015 was the wettest … Read more
Latest Forecast ➡ A new post about Tropical Storm Bill was started to help improve readability. All previous forecast updates in the three days leading up to Bill’s formation are archived below, in the order that they were written. ➡ Final Event Recap: As predicted, peak wind gusts of 50 mph and greater, and record … Read more
A follower asked, “if the water cycle is real, how can there be water shortages?” In light of the recent drought in Texas, which ultimately ended with the historic rainfall during the month of May 2015, and the ongoing devastating drought in California, I thought I would make this brief post. What is the Water … Read more
May 2015 was an exhausting month for forecasters in Oklahoma and Texas. One storm system after another brought enormous rainfall and significant flooding to many areas. I will try to post some dynamics/thermodynamics analyses or a general recap of each individual storm system in a future addendum to this post. For now, I wanted to … Read more
Many of you may have been awakened by the Tornado Warning in western Dallas/eastern Tarrant Counties early Sunday morning. The tornado sirens sounded across the warned area, and even in my area near the Grapevine/Southlake border. Fortunately the tornado in Irving dissipated as it moved north-northwest toward the residential areas of Carrollton. As it turns … Read more
Read Initial Forecast #1 | Use Radar/Advisory Tools on the DFW Page Final Update [Rainfall Record Broken – Sunday 5/24] DFW Airport received 3.31 inches of rain today (Sunday, May 24, 2015), which breaks the record for the greatest amount ever recorded on this date. The previous record was 3.28″ set in 1908. Records date … Read more
Below is my partial/subjective surface analysis using 2 pm data. There is certainly a convoluted mess of fronts associated with this surface low. However, the dry line is obvious with at least one dry-line bulge southwest of the metroplex. Surface-based convective available potential energy (CAPE) in that area exceeds 4,000 J/kg. There is a θe … Read more
Slow-moving, training supercells brought enormous rainfall amounts to the southern Oklahoma City metro on Wednesday, May 6, 2015. Rainfall rates of 3 to 4 inches per hour occurred with the thunderstorms. Update: The rainfall total has been updated to reflect the final official amount as confirmed by the NWS. The change was minor (a tenth of … Read more
Update #2 [Wednesday 4/22 10:40 pm] ***Severe Thunderstorm Watch*** A Severe Thunderstorm Watch has been issued for the thunderstorms that developed to the northwest as predicted. These continue to move southeast. The watch is in effect until 4 am. Read my initial forecast discussion posted the day before, on Tuesday 4/21 Update#1 [Radar Update – … Read more
Special Update [Saturday 4/18 7:40 pm] Significant thunderstorm wind damage is likely in the path of this downburst throughout Tarrant County, with winds in excess of 70 mph possible. It is moving northeast through Tarrant County. Velocity Image at 7:40 pm: Fourth Forecast Update [Saturday 4/18 5:45 pm] ***Severe Thunderstorm Watch Until 1 am*** Includes … Read more
UPDATE: Thursday 4/9 at 4 pm [Update Regarding Convective Initiation]: My map yesterday placed convective initiation along a McKinney to DFW Airport to Stephenville line. I am adjusting it west by about 20 miles to from Pilot Point to Fort Worth to Stephenville. This shift wouldn’t normally be significant (it’s within the margin of error), … Read more
→ Read my initial forecast published on Saturday, March 21 Final Update – Observed Low Temperatures on the morning of March 29, 2014 The freeze that was predicted for over a week verified perfectly. All locations in northern Georgia fell below freezing for 4 or more hours Saturday night/Sunday morning. I’ve gone through the observations, … Read more
Update #5 Friday 3/20 at 1:30 pm [Final Update]: A few official rainfall amounts over the past 24 hours Sister Grove Ck (Collin): 1.86 Melissa (Collin): 1.43 Prosper (Collin): 1.24 Dallas, Irving Blvd (Dallas): 0.51 Gainesville (Cooke): 1.56 Valley View (Cooke): 1.67 Denton (Denton): 0.81 Ladonia (Fannin): 2.93 Celeste (Hunt): 2.17 Alvord (Wise): 1.14 Update … Read more
The United States is also home to the most frequent occurrence and the largest variety of extreme weather events of any other country in the world. These events include, but are not limited to, extreme heat/cold, snowstorms, tropical storms and hurricanes, droughts, areal and flash floods, hail storms, and tornadoes. While none of this is … Read more
Cold-air damming (CAD), often called “the wedge” in the Southeast, is an interesting meteorological feature that can result in tricky forecasts for meteorologists. Topography plays a major role in CAD events, and you need a mountainous range for this feature to develop. While CAD can occur in the Rockies, it is predominant east of the … Read more
Below are details of the March 4th-5th 2015 snowstorm in North Texas. You may be interested in these related pages: DFW snowfall records dating back to 1898 List of the worst snowstorms to hit DFW (top 20) 2015 snow and sleet events (2014-2015 winter) Current snow cover map (updated daily) Daily Snowfall Accum Stats for … Read more
For a brief moment, it will feel like spring in northern Georgia. I expect temperatures on Wednesday (3/4) to be in the lower 70s. However, an Arctic front will move through Atlanta on Thursday morning, with temperatures falling through the 30s. Low temperatures Friday morning (3/6) will be in the lower 20s. A lot of … Read more
Final Update: Thursday 3/5 9 pm: View the storm reports Discussion #6 Wednesday 3/4 at noon: ***Winter Storm Warning is in Effect*** I have been analyzing vertical thermodynamic profiles at various times over the next 15 hours and the evolution of the atmosphere continues to support a transition from rain to freezing rain this afternoon, … Read more
The map below shows the actual snowfall accumulations on February 27, 2015 in North Texas. Parts of North Texas received over 6 inches of snow. The accumulation map was prepared by the NWS in Fort Worth using more than 200 ground reports. Official Metroplex Airport Reports DFW Airport: 2 inches. Broke the previous daily record … Read more