Squall Lines and DXing

[eskipper411]

I have noticed that every time a major squall line or a line of thunderstorms that passes through, every long range tropospheric ducting opportunity is gone. Why?

 

[Tom Wells]

Vertical Ionization of air from the separation of charges in squall line/thunderstorms probably disturbs
the nice clean horizontal layers of ionized air that tropo dx reception relies upon.

 

[dxer720]

I've also noticed that the "local" (about 100-200 miles) tropo can be enhanced after a good squall line passes through. I remember back in the late 70s, getting strong Chicago FMs on a transistor radio in Janesville, WI.

 

[gar hi]

That probably wasn't a squall line associated with a front but just some good pop up thunderstorms like we get all the time in summer here in Florida.

I've noticed good regional tropo sometimes after those but I've never seen a squall line associated with a front do anything but eliminate tropo.

 

[BobOnTheJob]

I've seen a rainy day kill everything but ground wave on FM but haven't ever thought about the squall line and it's role in DX.

 

[schmave]

I've also noticed that the "local" (about 100-200 miles) tropo can be enhanced after a good squall line passes through. I remember back in the late 70s, getting strong Chicago FMs on a transistor radio in Janesville, WI.

Driving back from western Ohio to Columbus this past Monday, where pretty bad storms popped up all across the state, I was picking up Dayton and Lima FM well beyond where I should. I took at least three Dayton stations about 25 miles *east* of Columbus with me.

 

[eskipper411]

I noticed this on the VHF propagation map. Usually, I would see 250 km paths or that occasion 500 km DX but after that squall line moved through the SE on Sunday Night, it eliminated the entire DX paths.

 

[BRNout]

The passage of a line of storms may well wipe out dx - but not always. In other words: it depends. If the squall line is a cold front, which is followed by cooler, drier air, that will surely wipe out most ducting in the troposphere. However, there are times when a line of storms are not associated with a cold front. Sometimes they precede a warm front, in which case they are followed by even a warmer and moister air mass. This would tend to enhance tropospheric ducting. It also depends on your location. In the plains (especially the southern plains), you get 'dry line' thunderstorms which can be quite severe. Behind these storms would be a different, drier air mass at the surface. This would tend to wipe out the typical tropospheric ducting; however, I've also heard of long distance dx just behind the dry line because of the unique vertical profile of the colliding air masses.

There are dozens of scenarios that could be mentioned here. The best way to state this would be to say that storms absolutely do impact dx reception, but the impact (positive or negative) depends on the specific conditions that are in play. It would be a mistake to try and use a "rule of thumb" in such a case - it's a lot more complicated than that.

 

[eskipper411]

All tropospheric DXing is based solely off the cap. If we didn't have this cap (Thank Mexico), then no Tropo. Since I live in Texas, the dryline punches through everyday it seems like. 92 degrees for today's high. This cap is pretty strong too. Takes about 125 degrees to break that cap. So, it's a win/lose in my book. Win, I see tropo DX opportunities, lose, we say significant fire dangers and winds up to 60 mph in some cases during the dryline bulge.

 

[gamefreak]

About 10 Years ago where I used to live (Bartow, Fl) we had a really bad afternoon T-Storm. Lightning hit the house and then the power went out. Now I was 9 Years old and at the time didn't have cable. So I turned the TV back on and was picking up WESH Channel 2 (Orlando) and WCJB TV 20 from Gainesville. Both stations we usually didn't pick up. (Maybe WESH on a good Outdoor Antenna. But my family had the indoor dipole.) WCJB was a 140 Mile tropo.

 

[spunker88]

Florida is a great state for tropo conditions. Prevailing winds from the warm Gulf are probably the cause, but if you ever look at the tropo forecast you'll see the states around the Gulf always have decent tropo.
http://www.dxinfocentre.com/tropo.html

 

[nd2023]

Gulf tropo is legendary. I was in New Orleans 3 years ago and I picked up stations from Texas to Florida all day and stronger at night.

 

[jd]

Gulf tropo is legendary.

It sure is. It's really so common that Houston area rimshots may as well give it up when tropo kicks in, and because the market is so spread out a number of close-in Houston stations have problems as well.

One late spring morning in Port Aransas TX, on the middle Texas coast, I experienced some of the best DX-ing ever, with stations coming in from northern Mexico and the Rio Grande Valley of Texas all the way over to New Orleans. That really happens fairly often, but what made this particular day unique was that before the tropo was gone an impressive e-skip event began, with stations coming in from Illinois, Indiana, Kentucky and more. Eventually the e-skip took over completely and it stayed until a couple of hours before sunset, but the tropo returned later that night.