Trying to understand Prog Chart.

[AdamZ]

In my never ending attempts to understand Wx I am trying to understand the progression of Wx on the ADDs Prog charts. The first Chart is valid 12:00 UTC on Sunday June 15 The Second is valid at 00:00 Monday June 16. I am trying to understand how the low trough is forming from South Eastern PA running to South Western NC. On the second chart. Can anyone enlighten me. Thanks.

 

[dmccormack]

The trough forecast across NC/SC tomorrow interests me as well, as it's across my planned route of flight.

The SFC progs are to be taken with a good deal of skepticism 24 hours+ out.

A better long-term indicator of trends may be found on the 500mb chart on the Standard Briefing page on ADDS.

At around 18,000 feet (500mb), you'll see the formation of troughs, lows, and the upper level steering winds, thereby shedding light on the surface progs.

 

[AdamZ]

Dan, I check the 500mb chart and am trying to understand it and how it is relating to the prog chart. There is a low off Newfoundland and a low in Canada north of Minnisota. Is the peak in the line going up between the two lows and comming to a point over VT and NH with the light northeasterly winds the beginning of the formatin of that trough between the two lows and that will eventually comedown to the surface?

 

[flyersfan31]

No. That peak is a ridge.

Check out that little circle, 586, on the 1200zSat 500mb chart. That's a little closed low aloft. I'm guessing that's forecast to deepen and slide north over the subsequent 24-36hrs creating your trough aloft. That's my uneducated take on the story.

I can't wait for Scott D to weigh in and make me look like an idiot.

 

[AdamZ]

No. That peak is a ridge.

Check out that little circle, 586, on the 1200zSat 500mb chart. That's a little closed low aloft. I'm guessing that's forecast to deepen and slide north over the subsequent 24-36hrs creating your trough aloft.

As Homer would say "Doh"Of course it is. and I worded the question rather poorley what I really wanted to ask is how the ridge going up between the two lows or the area it covers is going to turn into a trough from the ridge?

I'll follow the charts and see if that area off Georgia deepens over the next 24 hrs. I love this stuff and want to know so much more about it.

 

[flyersfan31]

After looking a little more, I think that last hypothesis is in error. Continue the research!!!!. I'm thinking now that the big closed low over the Great Lakes may be forecast to slide down over carolinas in 48hrs to create a trough?

 

[Let'sgoflying!]

The only place I have seen insight into what the forecasters are thinking is go to this site and type in the location you are interested in...........
http://forecast.weather.gov/MapClic...&site=LWX&textField1=38.9&textField2=-77.0167

Then click on Forecast Discussion under "Additional Forecasts and Information" at the bottom of the page. Some forecasters are very frank about what they are seeing and why they think it will cause a particular phenomenon, ours will even say things like "I can't say what that is going to do, because....", rather cool.

 

[dmccormack]

After looking a little more, I think that last hypothesis is in error. Continue the research!!!!. I'm thinking now that the big closed low over the Great Lakes may be forecast to slide down over carolinas in 48hrs to create a trough?

Unlikely -- look at the rotation and consider the steering winds and Coriolis effect -- what would move the low?

More likely the trough is a result of the two weak Highs -- one off the coast, one near TX.

 

[AdamZ]

How would two weak highs create a trough unless taken over by a low and where would that low come from or form?

 

[TangoWhiskey]

No. That peak is a ridge.

I agree!

Check out that little circle, 586, on the 1200zSat 500mb chart. That's a little closed low aloft.

Isn't 586 higher in pressure than the other contours depicted? How, then, is it a closed low aloft? I'm cornfused. That's why I like these discussions... They either un-cornfuse me, or the cornfuse me more!

I can't wait for Scott D to weigh in and make me look like an idiot.

Me too!!

 

[dmccormack]

Look at the SFC progs now...

According to the 12 hr prog, the trough will form between two High pressure areas -- one off the coast, the other over central KY, both at 1016 mb.

 

[AdamZ]

I see that Dan. Perhaps the Low that was off NJ in my first image above was pushed back westward by the high that was to the north east and that created a low over NJ or NY and thus the trough. I dunno I'm still trying to figure out myself.

 

[flyersfan31]

Isn't 586 higher in pressure than the other contours depicted? How, then, is it a closed low aloft? I'm cornfused.

No you're not -- I just looked at the pretty circle and ignored the numbers. In my defense, my wife was yelling at me from downstairs to get off the computer and go play with the kids.

 

[flyersfan31]

More likely the trough is a result of the two weak Highs -- one off the coast, one near TX.

But why? How do they contribute to the trough formation? I'm not disagreeing, I'm curious. Interestingly, the trough disappears/reappears in alternating 12/24/36/48 surface progs as of this hour.

 

[AdamZ]

No you're not -- I just looked at the pretty circle and ignored the numbers. In my defense, my wife was yelling at me from downstairs to get off the computer and go play with the kids.

I'll vouch for him on that one.

 

[dmccormack]

Well, I flew that trough today -- twice.

Not so bad going east -- light to moderate precip along the route of flight, fairly smooth ride at 11,000 all the way to 3,000 with occasional bumps.

Coming back and hour later -- the warming uplift did what it does in summer and a line of Thunderstorms were headed our way.

We took off while the cells were still 30 nm west but 400' MSL hit rain, then into the clouds.

An hour solid IMC, then breakout above the lower broken layer.

 

[AdamZ]

dan what was your route or Flight aware page?

 

[dmccormack]

dan what was your route or Flight aware page?

KFWQ-EKN-ROA-GSO-SDZ-KCRE and reverse

Xpndr died on return flight (apparently) so no track on FA.

 

[EdFred]

What's great is when you check threads with linked pictures 5 days later and can say, "I don't see any system moving through PA, what are you talking about?"

 

[flyersfan31]

What's great is when you check threads with linked pictures 5 days later and can say, "I don't see any system moving through PA, what are you talking about?"

Ain't that the truth!!