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    Charlotte, NC (SW Lake Norman)

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  1. Image on left is the GFS Ensemble Mean (500mb Height Anomalies) which is the average of all GFS Ensemble Members (total of 21 members on these images). In the image on the right (Spaghetti Chart), each of the 21 ensemble members is represented by a single line. Looking at the red lines (21 total red lines), this is the forecasted 576 dm height line for each ensemble member, with the white line being the forecasted 576 dm height line from the operational model run of the GFS (green lines are each ensemble member for the forecasted 552 dm height line / white line is the GFS operational model run for the forecasted 552 dm height line). Two ways these can be used with forecasting: 1) How does the GFS Operational run compare with the ensemble members? In the black box that I added in the image off the Mid-Atlantic coast, you can see here that the GFS Operational model run (white line) is a southern outlier compared to the other ensemble members which aren't as deep (aren't as far south) with the trough that digs thru PA and off the Mid-Atlantic coast...and 2) How much uncertainty exists among the ensemble members? In the black circles that I added in the image along / off the west coast, you can see that the ensemble members along the California coast (black circle) show more uncertainty with more diverging solutions compared to the location midway between Hawaii and Alaska (black circle) where the ensemble members are more tightly packed. The term "Spaghetti" is used because as you go out in time with the model run, the ensemble member lines jumble all together as model uncertainty increases greatly. The psu ewall site from which these images are taken could use a facelift and modernization, but it has some excellent maps (4 panel / ensemble charts like these) and was ahead of its time when it first came out with its model images
  2. GSP NWS back at it again in their latest discussion As of 1150 AM: Sometimes in these situations, we must wait for the leopard to reveal his spots. That might be happening as of midday as satellite imagery/sfc obs are showing the wedge boundary/warm front moving northward. Meanwhile, radars show a narrow band of showers extending from the western tip of SC down to the east side of metro ATL. The lower Piedmont and Lakelands have broken out ahead of this line, and the little bit of insolation in that region should help the air mass recover across the Upstate and toward metro Charlotte. On this trend, it is reasonable to expect the boundary to make it north of I-85 in the early afternoon. We still wait for the SPC mesoanalysis to respond, but the 12Z model runs have no qualms in bringing a plume of 1500 J/kg of sfc-based CAPE into the Charlotte metro area in the late afternoon. Will this be enough to energize the line of convection as it moves in from the west? Some of the CAMs think so. Bottom line...at this point...in spite of the downgrade in risk this morning...think it best to not give up on this one just yet. The latest guidance theoretically has more than enough buoyancy and shear to support a few severe thunderstorms east of the mtns, with the overall best chance still to our east.
  3. Grass and trees don’t mix. Fescue is best in partial shade, but it doesn’t like growing close to the tree trunks providing the shade (that goes for most any grass really)
  4. Fall is by far the best time to plant Fescue for two main reasons. One, you want the roots to establish as deeply as possible thru winter and spring in year one before the heat hits, which is Fescue’s biggest enemy. Secondly, you need to put out crabgrass pre-emergent each spring and that pre-emergent will also prevent the grass seed from germinating. As Avdave mentioned, ideally you would have irrigation for Fescue. But if you don’t, you just have to let if go brown/dormant over summer. No big deal, it will come back in the fall for the most part, but you just want to keep the weeds out of it thru summer. This part of the country isn’t the best for growing grass. Too hot for cool season grasses. Too cold for warm season grasses. I guess if you have to seed in the spring you could seed the Fescue (get the Turf Type Tall Fescue and cut it high for better root growth) and don’t put out the pre-emergent but you’ll likely get a lot of ugly crabgrass in the summer. Other option is to put out summer zoysia or bermuda in May, but there’s no turning back to Fescue once you do that, you are all in
  5. Is it shady in your yard? Bermuda hates shade and loves sun
  6. It's all part of forecasting. Not just interpreting the models, but trying to predict ahead of time where they will end up at go time. Not easy
  7. One thing to think about with respect to sleet vs freezing rain when looking at soundings...the general rule is that once the warm layer exceeds +3C, the snowflake dropping down will completely melt (instead of partial melting of the snowflake when the warm layer is between +1C and +3C). Once full melting of the snowflake occurs, the raindrop can't refreeze back into sleet because it no longer has ice nuclei to refreeze onto. As long as the snowflake only partially melts, it can refreeze back into sleet because it still has ice nuclei contained in it. See the bolded text below from: https://www.mentalfloss.com/article/91745/7-wintery-facts-about-ice-freezing-rain-and-sleet Freezing rain forms when there’s an inversion layer present during a winter storm. An inversion layer occurs when a layer of warm air gets sandwiched between two colder air masses. Snowflakes fall through the warm layer and completely melt before reentering the subfreezing air near the surface. This newly formed raindrop can’t freeze back into ice because it doesn’t have a nucleus around which to freeze, so the raindrop becomes supercooled, meaning it remains in liquid state even as its temperature drops below freezing. Once the supercooled raindrop reaches the ground, the water instantly freezes into ice.
  8. Latest Model Surface Temperatures at 6AM Thursday at Hickory (HKY) / Greensboro (GSO) / Raleigh-Durham (RDU) Model: HKY / GSO / RDU Euro: 33 / 30 / 33 GFS: 32 / 29 / 31 GFS Para: 33 / 29 / 31 CMC: 30 / 28 / 30 ICON: 31 / 29 / 31 HRRR: 32 / 30 / 32 3km NAM: 32 / 30 32 2.5km Canadian RDPS: 30 / 27 / 32
  9. Meh, this isn't a setup for snow...pre-storm setup aloft isn't there to support the needed cold temperatures
  10. 12z IBM GRAF 4KM - https://twitter.com/MJVentrice/status/1362080627659575300
  11. Look above. The combination of the 850mb low on the MS/AL border and the 850mb high off the SE coast are funneling in warm air aloft. The winds shown here in the 850mb low level jet across east Bama to NW SC (higher than 50 knots) are higher than we normally see in a winter storm. Also, the pre-storm air mass is only marginally cold aloft....so, the strong winds aloft are bringing in the warm air, but it also means that the precip moving in with this jet will likely be moderate to heavy in nature for a few hours.
  12. You can go to postimages.org > Choose Images (to select your image or animated gif) > use Direct Link option
  13. Kathy coming in strong with post #1. Boom Euro sounding at Greensboro for 1AM Tues has 32 deg at the sfc with a +10C warm nose...probably as big a warm nose as you'll ever see with sfc at freezing or below
  14. Can’t recall so much angst over freezing rain in years past. Toughen up people
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