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Old 09-01-2018, 11:48 AM
 
Location: Near the Coast SWCT
83,500 posts, read 75,234,500 times
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Quote:
Originally Posted by nei View Post
what was the setup midsummer for hot weather and incessant rains and storms. Just on the edge of the high pressure allowing for instability ?

Ridge was over the Atlantic and we were on the Western side of the Jet Axis. That axis was shifting back and forth. 3 things gave us those rain chances..


1. Areas of LP's formed along it riding up the axis.
2. The flow was so tropical that the atmosphere was loaded with moisture.
3. Fronts come across from troughs digging down West of us.

The peak of the Ridge was centered more over Eastern Canada/Greenland Longitude vs recently which has been Montreal.

Here was pretty much the main set up. See the peak of the ridge not in picture and the trough digging down west of us. We were caught in the middle.

It was a pattern that gave us a lot of Thunderstorms too.




But wait.. there's more. Love how we get all different types of setups in a given month..


This was the setup on August 11th. An Upper Low. 'That' caused instability rains. That dove into the southeast because there was blocking from that Atlantic Ridge.

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Old 12-30-2018, 10:32 AM
 
Location: Near the Coast SWCT
83,500 posts, read 75,234,500 times
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Default Jet Streaks

The "little" surprise event this morning made me want to post about it in here.

It can lead to last minute changes in forecasts and can turn a nice day into a bad day. Where the strongest winds are at the upper levels 25,000-40,000+ feet can create precip.

If you look at my post with link above you'll see the winds were 100kts+ at 25,000 feet this morning across the region.

Pretty cool stuff!

Quote:
One of a forecaster's first thoughts when confronted with the 300/200 mb chart is the jet stream. The jet stream is a high velocity river of air that flows completely around the Earth at the mid-latitudes. During winter, the jet core is located generally closer to 300 millibars since the air is more cold and dense in the vicinity of the jet stream during the cool season. The 200 millibar chart is used for the jet stream in the warm season but either chart in most instances will suffice. Many hot air balloonists have tried to ride this river of air around the world with not much success for most. The river of air is not continuous. Embedded within the jet stream are higher velocity jet streaks. Jet streaks are segments of faster wind speed within the jet stream.

At 300 mb, the air density is much smaller than near the surface. A 100-knot wind at the 200/300 millibar level does not feel as strong as a 100 knot wind at the surface. Even though the density is smaller, these air currents have the power to drive the movement of storm systems and build troughs and ridges.

One jet streak can turn a beautiful Monday into a severe storm Tuesday, as we will see in an example later. Troughs and ridges are not only carved by warm air and cold air advection but also by the high momentum air of jet streaks. A significant jet streak has winds over 100 knots. Look at the 300 mb chart in this section labeled "Time 1". A jet streak exists from Colorado to Montana. The highest wind speeds in the jet streak (aka jet core, jet surge) are 130 knots (150 miles per hour) in southern Wyoming.

Parcels within the jet streak are diving to the southeast. The air's momentum forces a trough to develop across the Central US.

In "Time 2", the chart from 12 hours later, the jet streak has moved further to the southeast and the associated trough is becoming more amplified.

At "Time 3" the jet streak has turned the corner and is in the base of the trough. The trough is at maximum amplification. The trough will now move to the east and eventually to the northeast. It is difficult to determine the four quadrants of a jet streak when one "turns the corner". Divergence and rising motion are strongest to the north of the jet axis, such as in Tennessee during highly curved jet streaks.

RULE OF THUMB: If a jet streak exists on the left side of a trough and winds are stronger to the left of the trough (as it is in our example in "Time 1"), the trough will become more amplified with time and will dig in a southerly direction. If a jet streak exists on the right side of a trough and winds are stronger to the right of the trough, the trough will become less amplified with time and "lift out" in a northeasterly direction. If the winds are about the same on each side of the trough, it will stay at about the same amplification. This knowledge will make you a better forecaster! A jet streak progression is shown below
Source:


Read More:

Jet Stream Tutorial
Jet Streak Movement Tutorial
In Depth Jet Streak Tutorial
Entrance Region of Jet Streak
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Old 12-30-2018, 05:02 PM
 
Location: Near the Coast SWCT
83,500 posts, read 75,234,500 times
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Really good thread to follow regarding SSW(Sudden Stratospheric Warming event) and potential surface impacts.

Important point to note that other influences e.g. tropical forcings, sst patterns and other high latitude drivers which steer troposphere circulation, makes direct attribution of response to ssw more challenging

Click & Scroll.

https://twitter.com/Domeisen_D/statu...20833185234944
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Old 01-08-2019, 10:44 PM
 
Location: Near the Coast SWCT
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Want to know what makes Thunder louder and travel farther? A stable layer above us. This is interesting!

https://twitter.com/ryanhanrahan/sta...70829682212865
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Old 01-21-2019, 06:12 PM
 
Location: Near the Coast SWCT
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Temps crashed yesterday afternoon from 40s to single digits overnight and popping sounds were heard everywhere including some ground booms.

Frost Quakes. Lots of pressure under soil and in trees especially when its wet!

https://twitter.com/ryanhanrahan/sta...87180669370368
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Old 01-22-2019, 05:33 PM
 
Location: Near the Coast SWCT
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It takes a special atmospheric profile to make them but they really look cool when they fall! Snow needles.

https://twitter.com/wxjerdman/status...17754768486403

NWS Boston had something on this in their discussions.

Quote:
Mid level vortex that delivered the arctic airmass to the region
is now located over eastern New England. Warmer air aloft
(TROWAL) is beginning to wrap around the system cyclonically
into southern New England. This is resulting in lots of clouds
and some flurries/light snow from time to time across the area.
Not expecting any accumulation other than a possible dusting or
coating.

Any accumulating snow tonight will be confined to the outer Cape
from Provincetown to Chatham as WNW winds veer to the NNW,
providing a longer fetch. This will result more persistent ocean
effect snow showers across the outer Cape. Hi res guidance
offering up to 0.15 qpf thru tonight. Snow ratios not ideal as
it`s too cold with temps below -20C. Thus not looking at
dendrites but more snow grains and/or needles.
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Old 02-08-2019, 12:51 PM
 
Location: Near the Coast SWCT
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Fata Morgana?

https://twitter.com/NWSRapidCity/sta...73180199010304
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Old 02-19-2019, 09:46 PM
 
Location: Near the Coast SWCT
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Another case of "dont believe the extreme record you see"

https://twitter.com/DRmetwatch/statu...55399826178048
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Old 04-07-2019, 07:27 PM
 
Location: Near the Coast SWCT
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Sea breeze along the gulf current

https://twitter.com/WeatherFlowCHAS/...01420850368514
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Old 04-16-2019, 05:44 AM
 
Location: Near the Coast SWCT
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Cool marine layer graphic.

https://twitter.com/NWSSanDiego/stat...40555998584832

Our Marine layer here kills Thunderstorms many times, pretty cool to see a strong storm just die out..

also cool when the flow aloft is from the west but you see a thin layer of clouds or just a breeze coming from the east.

Many times I see thunderstorms just stay away from the coast and I watch them strengthen to my north over Danbury.
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