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April Observations and Discussion


Gastonwxman

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This is a repost of what Don Southerland posted a few hours ago on the general weather forum. He seems to think there will still be snow in the mountains so who knows?

The 4/20 0z GFS ensembles maintained their impressive heat signal for parts of the West:

GFSens042020120z96h.gif

With the highly amplified pattern that will be in place at the time of the excessive heat, a secondary story will likely be the strong storm that will bring some much needed drought-easing rains to the East. Heavy wet snow in the higher elevations of the Appalachians, especially the Central and Southern Appalachians also appears likely.

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Folks,

The 6z Goofy has the 0 C 850 line down to Savannah on 4/24, the furthest south yet for a Goofy run. KATL is now projected by MeteoStar to get all the way down to 36 on Tuesday, 4/24, while the 859 is -1 C. Exciting times. Stay tuned to this BB for further updates.

The 12z Goofy maintained the 6z's numbers. The 12z Doc is actually a bit warmer than the 12Z Goofy. So, they've switched places.

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The 12z Goofy maintained the 6z's numbers. The 12z Doc is actually a bit warmer than the 12Z Goofy. So, they've switched places.

The 18Z and 0Z Goofys' 0C 850 line gets down to Darien, GA, on 4/24 and MeteoStar has Savannah down to 40F per the 18Z!

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From my blog

A surface low is forecast to develop in the Gulf of Mexico Saturday night and move northeastward up the U.S. east coast. By early Monday the system is forecast to deepen into a monster mid lattitude cyclone.

Heavy rain will be possible across much of the eastern U.S. For inland areas, snow will be a threat from the mountains of TN/NC northward into western New York

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This sums it up nicely....sigh :gun_bandana::gun_bandana::gun_bandana:

CAE:

THE FORECAST AREA UNFORTUNATELY LOOKS TO BE IN BETWEEN FORCING

RELATED TO THE COLD FRONT AND FORCING ASSOCIATED WITH THE UPPER

LOW OVER THE GULF AND THEREFORE WILL LIKELY MISS OUT ON THE HIGHER

AMOUNTS OF PRECIPITATION. THE BEST MOISTURE FLUX OFF THE ATLANTIC

IS FOCUSED DURING THE 06Z-18Z TIME FRAME ON SUNDAY AND GENERALLY

FOCUSED EAST OF THE FORECAST AREA ALONG THE COASTAL PLAIN. THERE

IS ALSO THE POTENTIAL FOR CONVECTION OVER FLORIDA AND OFF THE

GEORGIA COAST ASSOCIATED WITH THE COASTAL LOW THAT MAY PREVENT

MOISTURE FROM ADVECTING AS FAR INLAND FURTHER REDUCING THE CHANCES

OF HIGHER PRECIPITATION AMOUNTS.

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No specific topic for this Monster? It's going to be something. First, kudos to ECMWF for capturing this pretty far out (Day 10) and then models kind of waffled on the exact placement. We still don't know exactly but its getting there. The 700mb will close off near DC to western Maryland by early Monday morning. 850 and 5h similar, so its pretty stacked and slightly wobbles northwest. The new NAM remains consistent with last couple of runs and 6z GFS trended slightly west. In a nutshell, good rains for much of Florida (badly needed) and an explosion of rain developing in coastal GA, central and eastern halves of the Carolinas Sunday. By Sunday night, the rain will lurch northwest toward northwest NC and southern half of Virginia thanks to how the incoming 5h vort captures and phases with the main system that is getting absorbed. There's going to be a tight cutoff probably, but so far RUC and NAM have a secondary moisture shield on the northwest flank developing under extreme divergence and stalled lee trough in western SC/N. GA, then there may be a gap toward I-77 then a sudden increase in rain. It may all come together in one massive shield, or may kind of remain separate, but eventually the main shield associated with strong lift and the best 850 jet will surge northwest and north from eastern NC to Richmond and DC area, where the models have an uprecedented April Pwat anomaly of 4 to maybe 5 Standard Deviations. The dynamics are looking good, very good for any time of the year, and especially April.

For the cold advection and winds, its still early to say how much snow falls in West Va, western VA and northwest NC/ne TN. I'd say extreme eastern sliver of Ohio, down the Apps (all of West VA) and maybe even part of the lower elevations of western Virginia could see flakes. For NC and TN, it depends on how much moisture can wrap around the main low , or where the cutoff sets up. Any further west than NAM it would be a major snowstorm. Any further northeast (like GFS) then not much other than flurries to an inch, again another tight cutoff. Regardless, West Virginia to western PA and westrn NY are going to get a Big April Heavy Wet Snowstorm. Over a foot in several places, with high winds and blizzard conditions. It's probably not going to be an April 1987 repeat, but not a run of the mill situation either. East of the Apps, normal downslope drying, but high winds and mixing. The GFS last night had 30 mph surface winds pretty widespread, and I could see up to 40 or 50 with some gusts easily topping 40 MPH on a pretty widespread basis in westrn NC, SC and north GA on Monday, with instability showers and storms possible for northern and central NC as usually upper lows in that location pinwheel spokes of low based cumulus and sleet/hail/graupel. Should be good for taking rainbow pics east of the Apps Monday and possibly Tuesday.

post-38-0-18349000-1335023448.jpg

post-38-0-00928800-1335023474.gif

post-38-0-73023800-1335023490.gif

Impressive storm in many aspects if it lives up to its full potential:

*high rainfall rates and totals in eastern NC, central eastern VA to DC and up to Pa southern New England

*strong winds Apps down to Ga well into the piedmont Monday

*Soaking rains Drought plagued Florida

*Strong 3 to 4 contour cutoff, down to 534dm heights central Apps.

*More freeze possible outside mountains Tue and Wed AM some areas of Tenn Valley and upper Southeast.

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Just to add to what Robert has said, the 12z NAM has 18" of snow in pittsburgh:

http://68.226.77.253...FC/NAM_kpit.txt

I just read AFD from PIT and they aren't buying any accums in the metro. Just the ridges. When I read Charleston West VA AFD, I could hardly believe it. Not much mention of snow or the winds there. The storm would really have to move far east to have that forecast come anywhere close to correct.

this is the Charleston West VA forecast:

MONDAY...PARTLY SUNNY IN THE MORNING

THEN BECOMING MOSTLY CLOUDY.

A 20 PERCENT CHANCE OF SHOWERS. BREEZY WITH HIGHS AROUND 50.

NORTHWEST WINDS 15 TO 20 MPH WITH GUSTS UP TO 30 MPH.

MONDAY NIGHT

MOSTLY CLOUDY AND BREEZY. LOWS IN THE UPPER 30S.

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Getting way more rain than the NWS forecasted here. Then tonight is when the majority of the rain will come. JAX said .25 to an inch across Southeast Georgia. Already reached past the .25 mark. Just a little southeast of here already almost 2 inches. Loving this rain and wind currently.

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Wow! Its raining so hard outside. Must be about 2-3 inch hour rates. Streets are starting to flood. Thundering and very windy too! Gusts anywhere between 40-50mph.

Edit: Power was out for a little. Lightning about struck the computer and that made it restart. Streets flooded. Weird how the winds shifted direction and came in the other way and gusted to about 60mph. Lightning and thunder currently going crazy. Saw probably about 2-3 inches of rain.

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Man...this has been a boring spring as far as severe weather goes in the Southeast/Southern Appalachian Region. While some have complained about those 80 degree days, I've enjoyed it. And on that note, I'm ready for that transition to summer...also known as, the month of May. Bring on the humidity and storms.

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Folks,

KATL is running about 4 F warmer than the 18Z GFS' MeteoStar output suggested fwiw. It has KATL getting down to 39 F for a low tonight. So, my best guess is that KATL will remain at 40+ F and may stay as high as ~42-3F for the low tonight. We'll see.

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Folks,

KATL is running about 4 F warmer than the 18Z GFS' MeteoStar output suggested fwiw. It has KATL getting down to 39 F for a low tonight. So, my best guess is that KATL will remain at 40+ F and may stay as high as ~42-3F for the low tonight. We'll see.

Got down to 39 here this morning.

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Got down to 39 here this morning.

Impressive! KATL's low turned out to be 43. So, GFS MeteoStar did end up 4 too cold....no surprise. Today, the 6Z GFS based on MeteoStar is going for a high of 58, which is very believable, and a low of 38 tonight.

KSAV got down to 46 this morning, which is only about one warmer than MeteoStar had. Tonight it is projecting 41.

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Impressive! KATL's low turned out to be 43. So, GFS MeteoStar did end up 4 too cold....no surprise. Today, the 6Z GFS based on MeteoStar is going for a high of 58, which is very believable, and a low of 38 tonight.

KSAV got down to 46 this morning, which is only about one warmer than MeteoStar had.

Surrounding areas also reported upper 30 readings too.

I'm wondering if cloud cover had anything to do with it because I noticed rome only got down to 42, normally a sign of post frontal cloud cover because they are often colder than atlanta and do not suffer from the heat island effect. Plus It's rare my location is colder than areas further west (including atlanta...which is either around the same temp or even a little cooler) during these post frontal/windy situations due to downslope warming, even though we clear out much sooner. But true to form, we were clear here all night (perfectly clear here at sunset)

So, as I was writing this post, I went back and looked at the observations and indeed atlanta reported partly cloudy conditions for a good portion of the night, and rome was even cloudy for the evening hours..although they reported clear skies later on....but those few hours probably made the difference.

My location and surrounding areas, usually are colder the second and third nights because of the calm winds and lack of downslope. Also of note is the winds were higher in atlanta, (again normally the case) than here for a good portion of the night. Although we normally are warmer on nights/mornings like these than areas further west, it was one time we were not.

FFC is forecasting a low of around 37 here tomorrow morning, which probably means I'll be several degrees colder. (they are almost always too warm here in such situations..my location and surrounding areas are much more like FFC (which we all know sits in a hole of sorts and is often a good bit colder than areas like atlanta..where they are predicting 34 for tonight)

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I picked up a bit more in the last few hours. .60 since midnight. April total 1.51. NEED MORE!

Still down over 4" for the year, hope that number starts to go down as the year progresses :(

1.32" storm total.

Sweet! :thumbsup:

Well, your time had to eventually make it! I expect people are wandering around in shock at the sight of it :) T

:lol: It seems CAE picked up a bit more with a line that rolled threw around 8:00 last night. Here's something I haven't seen in a very long time :wub:

RECORD EVENT REPORT

NATIONAL WEATHER SERVICE COLUMBIA SC

0209 AM EDT MON APR 23 2012

...RECORD DAILY MAXIMUM RAINFALL SET AT COLUMBIA METRO AIRPORT SC...

A RECORD RAINFALL OF 1.76 INCHES WAS SET AT COLUMBIA METRO AIRPORT

SC YESTERDAY. THIS BREAKS THE OLD RECORD OF 1.69 SET IN 1907.

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