How much weight do you give Convective SIGMETs?

jsstevens

jsstevens

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jsstevens
I planned to fly from Sanford FL, (KSFB) to Gainesville, FL (KGNV) this morning to have breakfast with my son. I'm IR and current and I filed flight plans for both ways (as separate plans) so I wasn't worried about some clouds. However, when I was checking the weather this morning, I saw a Convective SIGMET over most of my route at the time I'd need to return. Since I have appointments this afternoon, I couldn't just wait it out. So I scrubbed.

I even looked up the definition and it says "
Convective SIGMETs are issued in the conterminous U.S. if these conditions are occurring or expected to occur:

  • Line of thunderstorms at least 60 miles long with thunderstorms affecting 40% of its length.
  • Area of thunderstorms covering at least 40% of the area concerned and exhibiting a very strong radar reflectivity or a significant satellite or lightning signature.
  • Embedded or severe thunderstorms expected to occur for more than 30 minutes.
Special issuance criteria include:

  • tornado
  • hail greater than or equal to 3/4 inches in diameter
  • wind gusts greater than or equal to 50 knots"
This seemed bad to fly through. Now that the time has passed, the storms (which apparently included rotation that might form tornados) never cam ashore. They remained in the gulf west of Florida.

I know that weather forecasting is not an exact science (with apologies to the metorologists) but how do you decide go/no go?

John
 
They play a factor for me, but they’re not the end all. I rather know what the underlying factors at play are and monitor the trends. I’ve flown through active convective SIGMETs many times and it’s been a nothing-burger, other times there’s some pretty significant phenomena going on that’s been an automatic no-go. Just really depends.
 
dmspilot said:
Basically none. I look at the prog charts, TAFs, MOS forecasts, and read the aviation forecast discussion.
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This is key. The forecaster discussion will often give a good sense of the nature of the connective activity, the confidence of the forecast and the reason for issuing the sigmet. Often the scientific forecaster discussion is the deciding factor of a go/no-go decision.
 
“No-go” is never a bad decision. “Go” might be.

My plane and I are both VFR only, so I’m pretty conservative. I give considerable weight to convective sigmets. Even if the convective activity doesn’t turn out to be a problem, there’s still a good likelihood of clouds and low ceilings that could be a problem for a VFR pilot.

I know you’re IFR rated, but I believe it’s rather recent. With low IFR time, I think you made you made a good decision.
 
Fly the airplane and what you see, you can always divert. I found that flying in Florida you might have a storm cell (which I would not fly in), on the left and divert a couple miles off coast and you’re fine or vice versa. Maintain day VFR and you’re fine, keep an eye on possible turbulence that may affect your enjoyment of the flight.

Now at night time, and in the clouds, that I’m not sure. Not brave enough to add extra elements to the equation.
 
Here’s my take… even my Pietenpol can outrun the most fastest storm… but precious few airplanes can out run DEVELOPMENT at its worst.

If I plan to simply stay below and VMC, meh. In a layer with no ADSB WX in, and imbedded t-storms might develop? Not going. And so on…
 
Tools said:
Here’s my take… even my Pietenpol can outrun the most fastest storm… but precious few airplanes can out run DEVELOPMENT at its worst.

If I plan to simply stay below and VMC, meh. In a layer with no ADSB WX in, and imbedded t-storms might develop? Not going. And so on…
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Yeah that’s what I noticed, your advantage here is storms move slow, sort of.
 
dmspilot said:
Basically none. I look at the prog charts, TAFs, MOS forecasts, and read the aviation forecast discussion.
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This. Plus radar. I live in Florida and if Convective SIGMETs were a factor I'd never fly. IMO they might mean something in other parts of the country but in the SE it's akin to saying the sun will rise in the morning and set in the evening. Personally I'm more interested in turbulence SIGMETs.
 
tsts4 said:
This. Plus radar. I live in Florida and if Convective SIGMETs were a factor I'd never fly. IMO they might mean something in other parts of the country but in the SE it's akin to saying the sun will rise in the morning and set in the evening. Personally I'm more interested in turbulence SIGMETs.
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I think that overstates it a bit. I’m in central Florida and fly quite a bit though I tend to avoid convective sigmets. Besides, much of the year has good wx. Summer tstorms are a fact of life here.
 
Half Fast said:
Summer tstorms are a fact of life here.
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That's my point. I live in Tampa and T-storms are a daily occurrence so a Convective SIGMET provides little in the way of useful info IMO to the point of being useless--for me. YMMV...
 
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There was a cold front moving from the north but it’s stalled and becoming an occluded front. That’s why I thought the SIGMET was here. Front pushing through at the time I was heading back coupled with not diverting due to other commitments.
 
Flying a good part of the year in Florida,I do pay attention to the connective sigs Also you can count on them being accurate on the route 4 corridor. It rains everyday somewhere in Florida.
 
jsstevens said:
I'm IR and current and I filed flight plans for both ways (as separate plans) so I wasn't worried about some clouds
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This is not really a plus in Florida summer with convective sigmets. It’s a bad idea to fly imc in Florida summer. I agree with the others that say the sigmets are pretty much constant and therefore useless, but only if you’re going to remain vfr. They are an excellent “don’t do that” for imc IMO.
 
The OP's dilemma was the return flight later in the day. Outbound, no problem: look at radar and the METARs and make an easy go/no go decision. The problem was later in the day and the strong need to make the return flight. Good decision to scrub.
 
I take them seriously but probably 75 % of the time, it’s not a no go for me. At work, I’d never fly during the summer if it came to a no go in convective sigmets. They’re over my area on a daily basis.

Plenty of times the graphical depiction covers a huge swath of airspace with the convective activity in them makes up a small percentage of the area. They aren’t all that accurate with valid times, developing vs dissipating , embedded vs area and severe classifications. Think they worst case it a lot.
 
IFR flight in the morning is usually OK but not when the thunderstorms are developing or developed in the afternoon
 
jsstevens said:
IFR flight in the morning is usually OK but not when the thunderstorms are developing or developed in the afternoon
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Afternoon storms have been my bane all summer. I can fly in the morning, but if I want to go somewhere and spend the day I likely won't be able to get home the same day. That should begin to abate in a few weeks or so.

(How can you tell when it's autumn in Florida? People begin to wear their dark bathing suits and temperatures plummet into the mid 80s.)
 
This is an excellent question/thread

mandm said:
Fly the airplane and what you see, you can always divert. I found that flying in Florida you might have a storm cell (which I would not fly in), on the left and divert a couple miles off coast and you’re fine or vice versa. Maintain day VFR and you’re fine, keep an eye on possible turbulence that may affect your enjoyment of the flight.

Now at night time, and in the clouds, that I’m not sure. Not brave enough to add extra elements to the equation.
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something that I've pondered a long time, is that it seems for the most part instructors don't do a really good job of this real world decision making. It's awful "easy" and safe to say no-go......but finding that grey line of real world practicality vs to great a risk, is not so "easy". I know people go up and are successful at picking the way through or around every day...but getting practice doing that with experienced help is not so easy.
 
I should have added....I would have scrubbed for sure.
& I would have been asking the same question, in hind site after seeing that I probably could have made it without problem.
 
Half Fast said:
“No-go” is never a bad decision. “Go” might be.

My plane and I are both VFR only, so I’m pretty conservative. I give considerable weight to convective sigmets. Even if the convective activity doesn’t turn out to be a problem, there’s still a good likelihood of clouds and low ceilings that could be a problem for a VFR pilot.

I know you’re IFR rated, but I believe it’s rather recent. With low IFR time, I think you made you made a good decision.
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An IFR rating does not give you any extra protection in this case. With a convective sigment, I would rather fly VFR than IFR.
 
dmspilot said:
Basically none. I look at the prog charts, TAFs, MOS forecasts, and read the aviation forecast discussion.
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^^^This^^^ When I see a Convective SIGMET, it is another data point. By itself, it doesn't do much for me, in general I may still fly (or not). It's not until I get the rest of the information as @dmspilot mentions that I can figure out my go/no-go.

My recent example is flying across FL (MLB) over to Tampa to pick up my daughter from UT. Had a convective SIGMET but the details were evening widespread t-storms (typical of Florida summer time). I filed IFR over and back and over was just a regular day flight. I knew it was coming in the evening and I knew it was going to clear out around 10pm to midnight and become clearer in the South (of Tampa) sooner and then continue to clear to the North. I made a Plan B and Plan C (my "outs") and they were wait for it to clear out if those forecast details/timeframe held true OR get a hotel and fly back the next morning if it wasn't clearing. We ended up waiting it out and flew South (~50 miles out of the way to the South) and it was a clear smooth flight. So we had to be flexible in our timing. If we had a schedule to maintain, I probably would have chosen to drive in this example.

Fast forward to today... my daughter wants to come home this weekend again. We have a convective SIGMETs (again). This time, my wife is driving over to get her. So both times, convective SIGMETs... different go/no-go decisions.
 
In central Florida we might as well have a permanent Convective SIGMET from June through September.

The real art of Florida flying is learning how and why summer thunderstorms form and move. Best source for that is the local TV news. Marine activity is huge in Florida, and weather is serious business for boaters too. Bay News 9 in Tampa has excellent weather, and the weatherman usually takes the time to explain how daily and seasonal patterns interact. A few minutes watching the night before or morning of a flight will help you anticipate when and where the worst storms will develop and which way they will move. It's not the same every day.
 
Florida, pretty much ignore it, or rather use other sources to figure out what is going on. Midwest, New England etc. Pay way more attention. Look for a line squall and not going near it.
 
A convective sigmet is informational, nothing more, nothing less.

Fly to your comfort zone.
 
As others have said, the bigger picture is more informative. Wide spread thunderstorms? Hard no go. Isolated? Maybe, it depends on how isolated.

I flew VFR about 2 weeks ago with a sigmet covering my route. Storms were predicted widely scattered and wound up earlier than predicted. On the return home, we had to dodge rain, but stayed in the clear. Over the airport, light rain had moved in, but looked worse on the radar than it did actual, 10 miles out I could still pick out landmarks. Fully prepared to land somewhere else if needed, but kept checking I had multiple outs and in the end I didn't need them. The way the rain was coming, there was a fairly well defined boundary in front of me and clear behind me, so I felt comfortable pushing on.
 
One of the items a convective SIGMETs can be issued for is
Radiological cloud. I think I would change heading for that.
 
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