Jan 24-26 Weekend Snow and Sleetfest Model Thread Part Tres

[pazzo83]

23/2 now - dropping like a rock

[Yeoman]

Just now, bncho said:

I actually planned on doing a revised forecast tonight, but the models are not handling the HP out west well at all. I'll release a final call tomorrow at 18z.

Rats

[Solution Man]

4 minutes ago, bncho said:

I actually planned on doing a revised forecast tonight, but the models are not handling the HP out west well at all. I'll release a final call tomorrow at 18z.

I’ll release mine Sunday night

[Warm Nose]

1 minute ago, DDweatherman said:

Why not just do it Sunday at 2pm? I do think that nowcast does bode well for us, less ML warm tongues out there. 

[Yeoman]

2 minutes ago, DDweatherman said:

Why not just do it Sunday at 2pm? I do think that nowcast does bode well for us, less ML warm tongues out there. 

ChatGPT is in its wheelhouse around 18z

[LeesburgWx]

1 minute ago, Yeoman said:

Rats

Omg, I just laughed so hard. Also, are we in GFS wheelhouse yet?

[wxlvr]

2 hours ago, nj2va said:

That was a fantastic run for us.  We hold until 18z with about 0.9” QPF by then.  

Here’s 18z at DCA.

To me, this does look like freezing rain at 00z Monday but someone much smarter could correct me.

Question for the group....Is there a tutorial on how to read these soundings?  I want to understand what they are telling, but I can't get there.

[nukeing]

Already 16 here in mt airy where forecast is ~22

Sent from my Pixel 9 Pro XL using Tapatalk

[GreyHat]

Delaware 

25F 

Real feel 16F

Winds N 14

[Interstate]

6 minutes ago, bncho said:

I actually planned on doing a revised forecast tonight, but the models are not handling the HP out west well at all. I'll release a final call tomorrow at 18z.

Way to go out on a limb. Anyone can do a forecast on model output. You need to do your DD and do it yourself. 

[Maestrobjwa]

7 minutes ago, bncho said:

I actually planned on doing a revised forecast tonight, but the models are not handling the HP out west well at all. I'll release a final call tomorrow at 18z.

Modeling it too weak or too strong?

[87storms]

The upcoming forecast is starting to give off winter ‘94 vibes. Brutally cold for week’s at a time. Feb ‘94 gets mentioned because we were supposed to get a snowstorm, but there was a sneaky warm layer that gave us several inches of pure sleet from start to finish. 

[nw baltimore wx]

1 minute ago, wxlvr said:

Question for the group....Is there a tutorial on how to read these soundings?  I want to understand what they are telling, but I can't get there.

Google "how to read skew t chart"

[Berlin1926]

23 minutes ago, MillvilleWx said:

First Call Forecast 

Went with a EC/AIFS/AIGFS blend with a stronger push on the FGEN, front end thump to help with many on Sunday AM, but I am very very wary of the NAM Nest right now, so will revise if necessary tomorrow. For now, I'm sticking with this. I do think banding will be impressive area wide. Just a matter of how thermals behave. Going to be a big day of trend monitoring tomorrow. Also, the lines are imperfect. I wish I had a better program, but utilized Microsoft Designer and it wasn't too bad. Wil work with it. 

Can we get central VA...this the correct forum for Richmond, no?

[aldie 22]

24 minutes ago, MillvilleWx said:

First Call Forecast 

Went with a EC/AIFS/AIGFS blend with a stronger push on the FGEN, front end thump to help with many on Sunday AM, but I am very very wary of the NAM Nest right now, so will revise if necessary tomorrow. For now, I'm sticking with this. I do think banding will be impressive area wide. Just a matter of how thermals behave. Going to be a big day of trend monitoring tomorrow. Also, the lines are imperfect. I wish I had a better program, but utilized Microsoft Designer and it wasn't too bad. Wil work with it. 

I look forward to that red line being adjusted south and east some 

[benjammin]

For whatever reason when forecasts or model maps are shared it seems like the default in this forum is to center the DMV and add some PA as well.

Sent from my Pixel 10 Pro XL using Tapatalk

[wxlvr]

3 minutes ago, nw baltimore wx said:

Google "how to read skew t chart"

oh my goodness, you don't know either?  Ok, I will research and let you know how to read them.

[MillvilleWx]

3 minutes ago, Berlin1926 said:

Can we get central VA...this the correct forum for Richmond, no?

I don't have a map for Richmond proper, but I do think there will be a lot of sleet and ZR down there. I would guess 2-4" of snow and sleet, but add 0.3-0.75" of freezing rain accretion on top of that. It's not looking good for south-central VA down into the Carolina Piedmont. Stay safe down there!

[stormtracker]

15 minutes ago, Wow said:

Enjoy ice!

Remember when you thought yalls area was the jackpot and gonna receive 2 ft?  How's it looking now?

[caviman2201]

For anyone who needed a little pick-me-up... 00z ICON held/improved a tiny bit... 

 

[nw baltimore wx]

1 minute ago, wxlvr said:

oh my goodness, you don't know either?  Ok, I will research and let you know how to read them.

I wasn't trying to be a smart-ass, but I look forward to your tutelage.

[MillvilleWx]

4 minutes ago, aldie 22 said:

I look forward to that red line being adjusted south and east some 

I would gladly if it came to it  

[nj2va]

Just now, caviman2201 said:

For anyone who needed a little pick-me-up... 00z ICON held/improved a tiny bit... 

 

Yeah it was a touch better for us.  At this point, I don’t think we’re going to see huge changes but 25-50 miles or 1-2 extra hours before sleet can mean 2-4” more of snow.

[Rvarookie]

Cold as a witches titty out 

[adelphi_sky]

Down to 24.1/5.9

[wxlvr]

2 minutes ago, nw baltimore wx said:

I wasn't trying to be a smart-ass, but I look forward to your tutelage.

here you go nw baltimore!  you can learn with me!  

•1y ago

 

 

A skew-T log-P diagram (commonly referred to as a skew-T chart) is a thermodynamic diagram used in meteorology to plot vertical profiles of temperature, dew point, and wind data in the atmosphere. It is a crucial tool for analyzing atmospheric stability and predicting weather phenomena like thunderstorms, cloud formation, and severe weather events.

Key Components of a Skew-T Chart:

1. Pressure Levels (y-axis, logarithmic scale):

The vertical axis represents pressure in millibars (mb), decreasing upward (standard surface pressure is around 1000 mb, and it decreases to about 100 mb at the tropopause).

These pressure levels correspond to different altitudes, with higher pressure representing lower altitudes.

2. Temperature (skewed x-axis):

The horizontal axis is skewed at a roughly 45° angle to the right, representing temperature in degrees Celsius. Lines running diagonally from the lower left to the upper right are isotherms (constant temperature lines).

Temperatures generally range from around -80°C to +40°C, depending on the altitude and the time of year.

3. Dry Adiabats (diagonal lines curving upward to the right):

These lines represent the rate at which dry air cools as it rises. Dry air cools at approximately 10°C per kilometer as it rises in the atmosphere.

If a parcel of air ascends with no condensation occurring, it will follow these lines.

4. Moist Adiabats (curved lines curving upward to the left):

These lines show the cooling rate of saturated air (air with 100% humidity), which cools more slowly due to the release of latent heat when water vapor condenses.

These lines start at similar angles to the dry adiabats but curve more sharply to the left with increasing altitude.

5. Mixing Ratio Lines (sloped lines nearly parallel to the isotherms, but slightly curved):

These lines show the mixing ratio, or the amount of water vapor in grams per kilogram of dry air. They are important for determining relative humidity.

They typically slope from the bottom left to the top right and can help identify the dew point at different altitudes.

6. Isobars (horizontal lines):

These are lines of constant pressure, running horizontally across the chart.

They help in reading the corresponding pressure levels for any given altitude.

7. Wind Barbs:

Plotted on the side of the chart (often to the right), wind barbs show wind speed and direction at various altitudes.

Each barb represents a different wind speed, with longer flags indicating higher wind speeds.

8. Parcel Path (convective parcel ascent):

A key application of the skew-T is following the path of a rising air parcel. You can assess whether it is stable or unstable by comparing the air temperature profile to the parcel’s temperature.

If the parcel's temperature remains warmer than the surrounding air, it is unstable and will continue to rise, indicating potential convective activity (like thunderstorms).

9. Lapse Rates:

Environmental Lapse Rate (ELR) is the actual rate at which temperature decreases with altitude. This is shown by the temperature profile.

Dry Adiabatic Lapse Rate (DALR) and Moist Adiabatic Lapse Rate (MALR) can be inferred by following the dry and moist adiabat lines, respectively.

10. Dew Point Curve:

The dew point curve, which represents the temperature at which the air becomes saturated, is plotted alongside the temperature profile but typically lies to the left of it.

The gap between the temperature and dew point curves indicates humidity; a smaller gap means higher humidity, while a larger gap means drier air.

Interpretation of Stability:

Stable Atmosphere: If the temperature profile decreases slowly with height or increases (inversion), a rising air parcel will cool faster than the surrounding environment, causing it to sink back down. This inhibits convection.

Unstable Atmosphere: If the environmental temperature decreases more rapidly than the dry or moist adiabatic lapse rate, a rising air parcel will remain warmer than the surrounding air, causing it to continue rising, which is conducive to storm development.

Conditionally Unstable Atmosphere: The atmosphere is stable for dry parcels but unstable for saturated parcels. If a parcel rises and becomes saturated, it could trigger convection.

Common Applications:

Cloud Formation: Where the parcel's temperature path crosses the dew point, clouds are likely to form at that level (this is known as the Lifting Condensation Level (LCL)).

CAPE and CIN:

CAPE (Convective Available Potential Energy) represents the area between the parcel's ascent curve and the environmental temperature curve where the parcel is warmer than the environment, indicating instability.

CIN (Convective Inhibition) is the opposite, representing stable areas where rising air is cooler than the surrounding environment.

Wind Shear: By observing the change in wind barbs with altitude, you can assess vertical wind shear, which is crucial in severe weather development.

By understanding these components, you can analyze a skew-T chart to assess atmospheric stability, identify potential weather hazards, and interpret vertical wind patterns.

[Solution Man]

Just now, wxlvr said:

here you go nw baltimore!  you can learn with me!  

•1y ago

 

 

A skew-T log-P diagram (commonly referred to as a skew-T chart) is a thermodynamic diagram used in meteorology to plot vertical profiles of temperature, dew point, and wind data in the atmosphere. It is a crucial tool for analyzing atmospheric stability and predicting weather phenomena like thunderstorms, cloud formation, and severe weather events.

Key Components of a Skew-T Chart:

1. Pressure Levels (y-axis, logarithmic scale):

The vertical axis represents pressure in millibars (mb), decreasing upward (standard surface pressure is around 1000 mb, and it decreases to about 100 mb at the tropopause).

These pressure levels correspond to different altitudes, with higher pressure representing lower altitudes.

2. Temperature (skewed x-axis):

The horizontal axis is skewed at a roughly 45° angle to the right, representing temperature in degrees Celsius. Lines running diagonally from the lower left to the upper right are isotherms (constant temperature lines).

Temperatures generally range from around -80°C to +40°C, depending on the altitude and the time of year.

3. Dry Adiabats (diagonal lines curving upward to the right):

These lines represent the rate at which dry air cools as it rises. Dry air cools at approximately 10°C per kilometer as it rises in the atmosphere.

If a parcel of air ascends with no condensation occurring, it will follow these lines.

4. Moist Adiabats (curved lines curving upward to the left):

These lines show the cooling rate of saturated air (air with 100% humidity), which cools more slowly due to the release of latent heat when water vapor condenses.

These lines start at similar angles to the dry adiabats but curve more sharply to the left with increasing altitude.

5. Mixing Ratio Lines (sloped lines nearly parallel to the isotherms, but slightly curved):

These lines show the mixing ratio, or the amount of water vapor in grams per kilogram of dry air. They are important for determining relative humidity.

They typically slope from the bottom left to the top right and can help identify the dew point at different altitudes.

6. Isobars (horizontal lines):

These are lines of constant pressure, running horizontally across the chart.

They help in reading the corresponding pressure levels for any given altitude.

7. Wind Barbs:

Plotted on the side of the chart (often to the right), wind barbs show wind speed and direction at various altitudes.

Each barb represents a different wind speed, with longer flags indicating higher wind speeds.

8. Parcel Path (convective parcel ascent):

A key application of the skew-T is following the path of a rising air parcel. You can assess whether it is stable or unstable by comparing the air temperature profile to the parcel’s temperature.

If the parcel's temperature remains warmer than the surrounding air, it is unstable and will continue to rise, indicating potential convective activity (like thunderstorms).

9. Lapse Rates:

Environmental Lapse Rate (ELR) is the actual rate at which temperature decreases with altitude. This is shown by the temperature profile.

Dry Adiabatic Lapse Rate (DALR) and Moist Adiabatic Lapse Rate (MALR) can be inferred by following the dry and moist adiabat lines, respectively.

10. Dew Point Curve:

The dew point curve, which represents the temperature at which the air becomes saturated, is plotted alongside the temperature profile but typically lies to the left of it.

The gap between the temperature and dew point curves indicates humidity; a smaller gap means higher humidity, while a larger gap means drier air.

Interpretation of Stability:

Stable Atmosphere: If the temperature profile decreases slowly with height or increases (inversion), a rising air parcel will cool faster than the surrounding environment, causing it to sink back down. This inhibits convection.

Unstable Atmosphere: If the environmental temperature decreases more rapidly than the dry or moist adiabatic lapse rate, a rising air parcel will remain warmer than the surrounding air, causing it to continue rising, which is conducive to storm development.

Conditionally Unstable Atmosphere: The atmosphere is stable for dry parcels but unstable for saturated parcels. If a parcel rises and becomes saturated, it could trigger convection.

Common Applications:

Cloud Formation: Where the parcel's temperature path crosses the dew point, clouds are likely to form at that level (this is known as the Lifting Condensation Level (LCL)).

CAPE and CIN:

CAPE (Convective Available Potential Energy) represents the area between the parcel's ascent curve and the environmental temperature curve where the parcel is warmer than the environment, indicating instability.

CIN (Convective Inhibition) is the opposite, representing stable areas where rising air is cooler than the surrounding environment.

Wind Shear: By observing the change in wind barbs with altitude, you can assess vertical wind shear, which is crucial in severe weather development.

By understanding these components, you can analyze a skew-T chart to assess atmospheric stability, identify potential weather hazards, and interpret vertical wind patterns.

Banter

[midatlanticweather]

17.1 with DP of 2. WC of 6

Brrrrr

 

[BTRWx's Thanks Giving]

4 minutes ago, wxlvr said:

Question for the group....Is there a tutorial on how to read these soundings?  I want to understand what they are telling, but I can't get there.

Red line is temperature. Green line is dew point. The solid black line that rises to the top right indicates the freezing level from the ground upward. Precipitation falls when the temperature and dew point line are touching at the bottom of the chart (the ground). Snow falls when the temperature and dew point lines stay to the left of the solid black freezing line. When you see the temperature line make a triangular shape bulge to the right of the freezing line, this indicates melting in that layer. If the raindrop continues to fall and the temperature line moves back to the left of the freezing line, the raindrop will refreeze. If the warm layer is high enough above the ground, the precipitation will be sleet,  but if the triangular bulge happens near the ground, then rain will re-freeze as freezing rain. 

[nj2va]

It’s been a long time since the whole area has been under a WSW