Go or No Go: afternoon buildups

As you walk into the FBO at Atlanta’s DeKalb Peachtree Airport, you have that nervous excitement that always comes before a flight. The goal today is to get to Tallahassee, Florida, so you can be at a meeting first thing tomorrow morning. On paper, this is an ideal trip for you and your Piper Arrow. It should take just over an hour and a half, and a colleague will be waiting to pick you up in Florida.

Of course the only question now is the weather. Let’s look at what your iPad has to say, then decide whether it’s a go or a no go. Departure time is 4:30 eastern, or 2030 Zulu.

Overview

The surface analysis shows no significant fronts or lows throughout the entire Southeast US, just a big high centered over southern New Jersey. That’s encouraging…

GNG surf ana

A quick glance at the ForeFlight map shows a more active picture than the surface analysis might suggest. Thunderstorms have developed over most of southern Georgia.

GNG radar route

Radar/Satellite

Looking closer at the radar image shows that southeastern Georgia is pretty well covered in storms and rain. But the western side, where your route of flight would go, looks much more scattered.

GNG radar regional

A look at the satellite image will help a lot: are these pop- up storms or part of a large weather system moving in? First the visible satellite.

GNG sat vis

Next the infrared satellite, which does a good job of showing where the tops are really high.

GNG sat inf

METARs

The weather at your departure airport (PDK) looks pretty good, with light winds and excellent visibility. The METAR confirms this, and the report from Tallahassee is equally encouraging, with light winds, good visibility and a broken layer at 5,500.

GNG METAR dep dest

Checking a few METARs en route also shows good conditions, with no significant clouds and good visibility. This suggests the weather is good VFR away from the storms.

GNG METAR en route

Forecasts

Something must be going on, though, for the radar to be that colorful. A look at the prog charts shows a weak stationary front is forecast to hang out over the panhandle of Florida, with scattered showers.

GNG prog 1 GNG prog 2 GNG prog 3 GNG prog 4

Next comes a look at the TAFs for departure and destination. Atlanta looks great, with light winds and VFR conditions well into the night. Tallahassee looks VFR, but thunderstorms are in the forecast throughout the afternoon and evening.

GNG TAFs

Convection

With all those storms, it’s not a bad idea to consult the experimental convective forecasts. These offer a fairly accurate look at short term convective activity. First is the 2100Z forecast chart:

GNG conv 1

Then, the 2300Z chart, which shows dissipating storms:

GNG conv 2

Decision time

It’s time to make the call – get in the Arrow and take off or get in the car and start driving? Given your experience, would you fly this trip? VFR or IFR? What route or altitude would you fly? Any concerns or questions?

Add a comment below with your answer, and explain your decision-making process.

20 Comments

  • Time to go flying!!

    Bring your ADS-B In with you. Based on the satellite picture, embedded thunderstorms shouldn’t be a concern along your route. You may need to weave around a build-up or two along the way, but that’s about it.

    VFR or IFR, either way seems fine to me.

    • Oh yeah, I almost forgot. Plan an alternate to the NW of Tallahassee in case there’s a thunderstorm over the field when you get there. If VFR, I’d fly 4500ft. If IFR, I’d file for above the tops of the scattered layer(s) enroute so I’m able to see any build-ups, so maybe 8,000ft.

  • Easy “go” decision with one caveat:

    If it’s a one way trip today and your return isn’t until the next afternoon, the frontal picture may change quite a bit tomorrow. Looks like the “stationary” front may be moving slowly to the southwest which could indicate that the system might block your return. If you have flexibility to delay your departure another day, not a problem. However, if you really have to get home the next day, maybe better to drive.

    One of the things about flying into Florida is that frontal systems quite frequently block the path into or out of the state, because they often intersect at an angle with the Gulf coast and extend well out into the Gulf. Unless you’re flying a twin, a long detour out over the Gulf is not for most light aircraft. I’ve been caught to the northwest wanting to get back to Florida and found a long impenetrable wall oriented NE to SW blocking the entrance to Florida, and had to wait until the following day.

  • I will say that I am a local pilot who is very familiar with the weather patterns in this area of the country as I am based out of an airport within 100 miles of KTLH and I have flown into both KTLH and KABY before. Considering that this flight is happening in the afternoon, I would recommend a no go because our weather in this area is notoriously famous for exploding in the afternoons. If you are prepared for a rough ride and the possibility of a divert then it would not be too bad. I would recommend playing wait and see. That radar pattern is notorious in these parts. Odds are strong there will be back building and strong storms later in the afternoon when you see it looking that bad. Yes the metars are good but I would put good old fashion local knowledge and experience at the same level as the weather forecasts any day when the conditions are questionable. That weather can turn into major thunderstorms very fast in this part of the country. Have an alternate airport and don’t even try it VFR unless you are prepared to pickup a popup IFR just in case. You might punch through but odds are strong that you won’t get back out on a day like this. Just recently I saw a pattern similar to this and I got that bad feeling. Long story short, there was weather coming in from the west on that day. I was flying strictly to build time towards a commercial ticket and ended up going to the east instead. When I landed and checked, it was obvious that I would have flown into a heap of weather hurt had I went west as planned. I still had to fly IFR back to my home field as the cloud bases dropped to 1500 feet where I was at and turned into a nice actual IFR day. Moral of the story, in the South East, you don’t play with the weather because it will bite you in an instant.

  • Go, if you’re prepared and willing to divert. I’d look at the moving radar picture to see what direction the weather is moving, and where the buildups are happening. I’d also take a few METARs and TAFs from enroute airports to see what the situation there is. But planning-wise, I’d have looked at the weather the day before. These buildups happen in the afternoon and leaving a few hours earlier could have made all the difference. Even taking an evening or morning flight might be a better choice. Also, in conditions like this I’d ONLY fly VFR, I wouldn’t risk flying through any clouds with convective activity in the area. You can’t go over, so 4500’ should keep you clear of clouds.

    • I agree with all of the above, but particularly Roca’s comment. I am a North Florida pilot and this time of year we will often have daily afternoon thunderstorms that can get very bad fast and are not something to mess with. For North Florida flying the best thing to do is to get up early and get as early a start as possible and plan on having your flight completed by Noon at the latest and preferably earlier than that.

  • Go, but:

    1. Go IFR (8,000 sounds about right), and weave. Don’t fly into any clouds except maybe the in-and-instantly-out type of non-build ups you know there is nothing behind. Don’t hesitate to ask for weaving route diversions and altitude changes. But keep in mind you’re flying an Arrow on a hot day, not a Pilatus. Altitude capability is an issue. As for IFR vs. VFR, if things go bad, you want max help instantly available. That means flying on an IFR clearance. I agree with having the alternate NW.

    2. Have Plan B, namely: At the PDK FBO, identify at least 2 airports on or west of your route that have rental cars, good current weather, and good forecasts. Call each to make sure they do have cars available, and ask them how bad the storm is there. If they say, “What storm?”, that’s good. Tell them what you’re doing, and that they may see you.

    3. Fly with the mindset that you are flying a series of legs (PDK to within easy reach of your first car rental airport, etc.). If you successfully complete the first leg, consider it a good day. Being able to successfully fly beyond the first leg is icing on tha cake. But don’t push it just because you like cake icing. And during each leg, be ready to retreat to the origin point of that leg, or to the NEAREST good weather airport if things go really bad. You do routinely keep track of those airports during every flight don’t you?

    4. And to heck with the meeting if things go bad. Land safely and fly another day. No meeting is worth having the BIG MEETING.

    • I really appreciate item number 3, for VFR only pilot, it’s a great way to think about the flight, plan for the contingencies and make it a go.

  • Here in San Diego (MYF) we have the same problem. It’s a beautiful blue sky day, but out in the distance you see monsters thunderstorms building up and by noon they are huge. If I am heading to Las Vegas and can not take off by 9am, I get in my car and drive. I tired to be brave once, and while it was simply uncomfortable for me, My two passengers made a mess at the Las Vegas executive airport bathroom. Lesson learned.

  • I live in Charlotte and afternoon pop thunderstorms can occur very quickly. I agree with all the previous comments especially the one that recommends flying early and to be on the ground by noon. I might stretch that to 2pm in my area. Also another caveat. I’ve been flying with ADSB for a year now and be very Leary about the weather you get in the cockpit. Metars can sometime be old. I’ve seen some over an hour old. I’m not sure why this occurs but definitely look at the timestamp on the report. I know the radar images are also delayed. I’ve read it’s about 15 minutes. Hopefully not much longer than this. Bottom line, keep looking out the window and use your best judgement.

  • I fly a route very similar to this one on a regular basis. Usually every two weeks from the Atlanta area to the Jacksonville area in a 1959 Piper Comanche with updated avionics. I agree with most of the comments above, except I find as much success leaving late as I do early. 2PM-6PM can be a bad time, but 7 PM until dark can be as good as earlier in the day. The difference is you are more likely to not have storms to deal with in the AM. In the evening, if that is your only option (which is usually the case for me) then the METARs and ADS-B are your guide to making a succesful trip, as well as pilot reports (can’t get enough of those). The key to these trips is remaining clear of clouds, if you can see you can avoid. I would be looking for areas where the storm has passed and for high over casts such as 9000 or above. I know from experience that area would be safe to fly through, usually in smooth air and light rain. Note: the goal is to arrive before dark again see and avoid is critical.

  • We get the same afternoon explosion of Thunderstorms in south Louisiana that they get along the Florida Gulf Coast in the summer. They usually begin to die down about an hour before sunset, but that’s no guarantee with that front laying across there. There’s an old saying, “If you have time to spare, go by air.” If you won’t get fired for missing the meeting, then take off, fly VFR, and plan on having to deviate some, however, if your job depends on it, jump in your car and hit the road. It’s really not that far. If you do fly and the weather gets worse, figure you might need to spend the night someplace besides home the day after the meeting. Regardless, just don’t get stupid and come down with a case of “Get There-itus” I’ve learned after over 60 years of flying including 30 on the airlines not to completely trust what the Weather Wizards predict.

  • COMPLAINT: If I want to show off my knowledge, I’d love your writing. But I want to learn about weather, and I don’t love your article format. If I wanted a pop quiz, I’d go back to school. So what’s missing? THE ANSWER! I don’t respect excellent questioners if they can’t have excellent answers ready to show me. This is my first negative comment to AirFacts Journal, and I hope my last. PLEASE PROVIDE YOUR ANSWERS UP-FRONT, AND DON’T WAIT FOR READERS’ HIGHLY VARIABLE INPUT.

    • I agree with Scott James below: the whole point of this series is that there is no single right answer. The purpose of the exercise is to do your own risk analysis and think about how you make decisions like this. What conditions are you comfortable with, given your experience and confidence levels? For a newly-license Private Pilot, this flight is probably a no-go. For me, it’s an easy go decision (after planning some outs to the west of course).

  • Jez Richard Tamir shouldn’t get on his computer before he has his coffee. The correct answer is there is no correct answer. It is just what you feel you can comfortably and safely fly. I used to be based at KPDK and we made trips like that all the time, even before ADS-B or even Stormscopes. BUT, you have listen to what weather ATC gives you and be ready to put the airplane on the ground and wait out the storms. As long as you are willing lounge around in an FBO (which might even have a radar picture), and finish the flight after dark it is perfectly safe.

  • Richard, you raise a good point. However, I am not sure that what you request is even possible. My experience is that there are no black and white answers and that the “answer” depends on variables such as your training, experience and the aircraft you fly. In addition, presenting a scenario causes a reader to think about what he or she would do while sitting comfortably at home rather than while sweating in a cockpit. It seems clear from the responses above that there are no “right” answers. Some pilots would fly IFR, others VFR; some would fly at 9000, others at 4500; some would wait until morning, others would fly in early evening. My sense is that each person as the pilot in command has to make the judgment call based on the particular factors present. Having the benefit of various points of view is “answer” enough for me.

  • This flight is clearly easy. There doesn’t appear to be any embedded stuff (but need more info), but PLENTY of space to make this trip.

    This is typical of the stuff we fly in the SE all the time, and it’s almost always doable, with minor deviations. Over the years, this kind of weather is always flyable, and there’s plenty of options. (Yes we need options on every flight).

    We can assume, this day and age, the aircraft has “some” weather avoidance, which will help. The Arrow is plenty capable, if the pilot is proficient.

    This would be a VFR trip for me. IFR adds very little benefit because you’re NOT going thru the cells and the rest of the weather is VFR. There doesn’t appear to be any layers that matter.

    I’d probably go at 4500 feet unless winds were really lousy there, but only an hour and a half.

    If a cell moves over the field, I’d slow as appropriate to let it clear. It would be very unlikely to cause a divert.

  • I see no reason to go IFR unless you just want the practice. But then you are may have trouble getting clearance to deviate because of other IFR traffic. Of course then you could always cancel. As Joseph said in the above post, I presume in answer to Richard Tamir’s post, there is no black & white answer. There are a bunch of various answers in these comments and they are all correct for the pilots who made them. As I said in my post, I’d go VFR and use Flight Following but that is what I would do. There is another old saying: “When in Doubt, Don’t.”

  • I would file an IFR flight plan prior to departure but fly the route VFR at 3,000 or below. I would use flight following if radar coverage permitted. ATC will give you real time weather warnings.

    If the weather started to deteriorate, I would activate the IFR flight plan in flight. Activating a flight plan is easier than filing one in flight. I would also be prepared to divert to the west if the weather deteriorated to the point that I felt it was unsafe to continue to my destination.

  • Beyond the TAF, read the local forecaster’s notes at:

    http://forecast.weather.gov/product_sites.php?site=CRH&product=AFD

    Depending on the forecaster, you will get a very personalized discussion of what he thinks might happen. In some cases, he/she will even tell you that there is a concern over T-storms but it is not yet significant enough to include in the TAF, and usually provides a description of the variables in play and what he may be looking for to trigger a TAF update. Last week, the DFW forecaster began his aviation summary with the phrase, “To convect or not to convect; that is the question.”

    Also, while you are on the experimental convection page, go down a ways and look at the Storm Prediction Center’s Day One convective outlook…and read the discussion. They don’t get everything, but it’s good background.

    Certainly look at the direction of movement, particularly the winds at 10,000 feet.

    You’re flying right into a TAF with a TS square in the middle of your ETA; there isn’t a dispatcher in the world who would release a Part 121 transport into that TAF without an alternate and plenty of gas to screw around with. Regardless of whether you go IFR or VFR, you need a viable alternate.

    It’s been so long since I flew VFR that I can’t offer an informed opinion. That said, it does seem that IFR, unless needed due to IMC, would make it harder to use altitude changes as part of an avoidance strategy. I do seem to recall weaving between rain shafts across the St. Mary’s River at about 800 feet back in 1976, en route to a stop at Craig Field when delivering a new Cessna 150 to Palm Beach…not a good planning tool, but still, an escape if needed…

    Finally, at the risk of plugging a friend’s book, read a copy of Dennis Newton’s Severe Weather Flying. Dennis wasn’t always a Boeing test pilot, and in retirement, he’s recently updated the book.

    Yes, I have craftily avoided answering the question, because I’m not a GA pilot and I’d probably make the wrong decision. That said, you can do a lot as long as there is always a place to put it on the ground handy and you’re prepared to use it.

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