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January Pattern and Storm Discussion


Cold Rain

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EPS stands for Ensemble Prediction System, right? Isn't that the same thing?

EPS is the same as ensemble mean. So yes. Idk what the control run is considering the mean is made up of 51 members including the op.

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EPS is the same as ensemble mean. So yes. Idk what the control run is considering the mean is made up of 51 members including the op.

The control run is normally run with the exact same initial conditions as the operational run, but the control run is computed against a lower resolution. So, this sounds like the Euro Control run, which would be one of the 51 ensemble members (with the Euro Operational run also being 1 of the 51 ensemble members)...but I don't know for sure.

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The control run is normally run with the exact same initial conditions as the operational run, but the control run is computed with a lower resolution. So, this sounds like the Euro Control run, which would be one of the 51 ensemble members...but I don't know for sure.

Correct, it's the control run, one of the members of the EPS.

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Well on the surface 12z is warmer than the 00z run of the GFS. Last night it had the 850 line running roughly across I-40 this one at @126 has it just above the border in VA and just slightly dips into the far NW corner of TN. It does look like the low is a tad bit stronger on this run though as it treks along the gulf coast.

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I've seen a few mets mention places could see their coldest readings since 2010-2011, with this cold surge. Mainly east coast cities.

Well if you like cold you'll be licking your chops at this run. It kind of moderates after 192 due to truncation. Even still though at least for NC until 240 it keeps it cold.

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From above, the overall wave pattern setup during the Jan 3-5 storm looks impressive. If the southern energy were modeled a bit more cohesively and not overplay the SE ridge shearing it apart, this would show a heck of a storm here. There are so many little shortwaves flying through the field it's difficult to model, but just as difficult to really develop a good storm.

SSt72.gif

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11AM HPC Discussion...

BY DAY 4 THE SYSTEM IN THE SOUTHWEST IS OUR FOCUS. THE 00Z GFS

BECAME FAST AND FLAT...AND WE DROP IT BY DAY 4. THE 00Z ECMWF WAS

BETTER UNTIL DAY 6...WHEN ITS PERFORMANCE IS MORE QUESTIONABLE

UPSTREAM IN THE PACIFIC. THE MODELS ARE STRUGGLING WITH SPLIT FLOW

IN THE EASTERN PACIFIC. TELECONNECTIONS BASED ON A PERSISTENT

NEGATIVE ANOMALY OVER NORTHERN QUEBEC WOULD FAVOR A MORE

SUPPRESSED SOUTHERN STORM TRACK THAN IS SEEN IN THE CURRENT

OPERATIONAL MODELS...WHICH ARE TENDING TO PRODUCE

PROGRESSIVE...STRONGER SYSTEMS IN A CONSOLIDATED FLOW STREAM

APPROACHING CALIFORNIA BY DAY 6/7. THUS...WE TURNED TO THE

ENSEMBLE MEANS...WHICH SHOW THIS SUPPRESSED LOOK...AND WE

PREFERRED THE ECMWF ENSEMBLE AND NAEFS...AS THE GEFS SHOWED SOME

OF THE PROGRESSIVE BIAS OF THE GFS.

...IMPACTS...

THE BLOCKY RIDGE/TROUGH COMBINATION OVER THE WEST, COMBINED WITH

THE SUPPRESSED POLAR JET OVER THE EAST SHOULD PRECLUDE WIDESPREAD,

HEAVY PRECIPITATION FOR ALL BUT THE GULF COAST STATES, WHERE WAVES

ALONG THE PRIMARY STORM TRACK SHOULD BE ABLE TO TAP GULF MOISTURE

AS THEY RIPPLE EASTWARD. HOW FAR NORTH THE PRECIPITATION GETS WITH

THESE WAVES IS DEPENDENT UPON WHERE THE CONFLUENCE RESIDES BETWEEN

THE SPLIT STREAMS. THE TELECONNECTIONS ARE DOING A GOOD JOB

DEPICTING THE EXPECTED TEMPERATURE REGIME...WITH BELOW NORMAL

TEMPS IN THE ARCTIC AIR THAT SLIPS THROUGH THE GREAT LAKES. THE

SAME TELECONNECTIONS WOULD SUGGEST LESSER PRECIPITATION CHANCE

INLAND OF THE GULF COAST. THIS IS REFLECTED IN POPS ACROSS THE

TENNESSEE VALLEY, SOUTHERN APPALACHIANS, CAROLINAS, AND MID

ATLANTIC STATES WHICH AT FIRST GLANCE APPEAR HIGH FOR REGIONS

ESSENTIALLY DOMINATED BY CONTINENTAL POLAR AIR.

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From above, the overall wave pattern setup during the Jan 3-5 storm looks impressive. If the southern energy were modeled a bit more cohesively and not overplay the SE ridge shearing it apart, this would show a heck of a storm here. There are so many little shortwaves flying through the field it's difficult to model, but just as difficult to really develop a good storm.

SSt72.gif

We won't have to worry about cutters with that look, question is would the supress to much and not allow amplification...

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11AM HPC Discussion...

BY DAY 4 THE SYSTEM IN THE SOUTHWEST IS OUR FOCUS. THE 00Z GFS

BECAME FAST AND FLAT...AND WE DROP IT BY DAY 4. THE 00Z ECMWF WAS

BETTER UNTIL DAY 6...WHEN ITS PERFORMANCE IS MORE QUESTIONABLE

UPSTREAM IN THE PACIFIC. THE MODELS ARE STRUGGLING WITH SPLIT FLOW

IN THE EASTERN PACIFIC. TELECONNECTIONS BASED ON A PERSISTENT

NEGATIVE ANOMALY OVER NORTHERN QUEBEC WOULD FAVOR A MORE

SUPPRESSED SOUTHERN STORM TRACK THAN IS SEEN IN THE CURRENT

OPERATIONAL MODELS...WHICH ARE TENDING TO PRODUCE

PROGRESSIVE...STRONGER SYSTEMS IN A CONSOLIDATED FLOW STREAM

APPROACHING CALIFORNIA BY DAY 6/7. THUS...WE TURNED TO THE

ENSEMBLE MEANS...WHICH SHOW THIS SUPPRESSED LOOK...AND WE

PREFERRED THE ECMWF ENSEMBLE AND NAEFS...AS THE GEFS SHOWED SOME

OF THE PROGRESSIVE BIAS OF THE GFS.

...IMPACTS...

THE BLOCKY RIDGE/TROUGH COMBINATION OVER THE WEST, COMBINED WITH

THE SUPPRESSED POLAR JET OVER THE EAST SHOULD PRECLUDE WIDESPREAD,

HEAVY PRECIPITATION FOR ALL BUT THE GULF COAST STATES, WHERE WAVES

ALONG THE PRIMARY STORM TRACK SHOULD BE ABLE TO TAP GULF MOISTURE

AS THEY RIPPLE EASTWARD. HOW FAR NORTH THE PRECIPITATION GETS WITH

THESE WAVES IS DEPENDENT UPON WHERE THE CONFLUENCE RESIDES BETWEEN

THE SPLIT STREAMS. THE TELECONNECTIONS ARE DOING A GOOD JOB

DEPICTING THE EXPECTED TEMPERATURE REGIME...WITH BELOW NORMAL

TEMPS IN THE ARCTIC AIR THAT SLIPS THROUGH THE GREAT LAKES. THE

SAME TELECONNECTIONS WOULD SUGGEST LESSER PRECIPITATION CHANCE

INLAND OF THE GULF COAST. THIS IS REFLECTED IN POPS ACROSS THE

TENNESSEE VALLEY, SOUTHERN APPALACHIANS, CAROLINAS, AND MID

ATLANTIC STATES WHICH AT FIRST GLANCE APPEAR HIGH FOR REGIONS

ESSENTIALLY DOMINATED BY CONTINENTAL POLAR AIR.

The last sentence doesn't sound real positive or am I misreading that? Sounds like they are saying precip will be hard to come by?

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It does, but it also sounds like they are going with the cold pressing a little farther south - the cold air is the much bigger concern to me.

Agreed. The way it reads implies that those regions would be predominantly influenced by polar air (dry). Please correct me if I am wrong.

Timing seems too early for there to be a correlation between the pressing polar air and forecasted strat warming though, right?

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Not bad for the 12z GEFS...

The 6z GEFS was similar but it only looked that way because the individual members were all over the place with timing (some were much slower than the others) and track (some were app runners). I don't believe even one member had snow outside of the mountains. We'll see what the 12z looks like in a bit. Looks to be a strung out mess if my suspicions are correct. We have definitely had a pattern change to a more active and wetter one. Now we need the cold air to get with it!

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The 6z GEFS was similar but it only looked that way because the individual members were all over the place with timing (some were much slower than the others) and track (some were app runners). I don't believe even one member had snow outside of the mountains. We'll see what the 12z looks like in a bit. Looks to be a strung out mess if my suspicions are correct. We have definitely had a pattern change to a more active and wetter one. Now we need the cold air to get with it!

Really? I glanced at them at 192 and thought I saw 4 out of 12 members. I bet 12z has a few, I hope...

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