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Everything posted by BlueRidgeFolklore
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They should have waited until the 18z NAM ran...... .SHORT TERM /SATURDAY THROUGH MONDAY/... As of 250 PM Thu: Still high confidence on the occurrence of a winter storm developing late Saturday into early Sunday across the region. Trends in the models unfortunately do not lend much additional confidence to precip types or transitions. Cold-air damming still is a key component of the event. The models suggest the CAD will be a bit stronger at the onset of precip, which looks most likely Saturday afternoon as a stationary front sets up between the incoming continental sfc high and the developing coastal low. The general track of the low is still expected to be across the Coastal Plain to our south, so the timing of the event has changed little. One appreciable difference with this fcst package is lower overall QPF. Unfortunately for the sake of forecasting p-type distribution/transitions, models continue to show midlevel temps flirting with 0C for much of the event. Temps are expected to remain above freezing for most of the area Saturday afternoon, though the trend has been colder in latest guidance. A deep but relatively cool warm layer aloft implies a mix of precip types is possible late Saturday; increasing precip should strengthen the wedge through diabatic cooling and profiles will support all snow over an increasing portion of WNC through Sunday morning. Sfc temps Sunday are especially tricky given guidance split across the freezing mark. Have biased the fcst in favor of a GFS-based blend that did well in last month`s wintry wedge event. Still, where temps are above freezing sleet is expected to be the main p-type. The NAM is substantially warmer with temps aloft than any of the global models we have at our disposal. For now the NAM profiles are being discounted and not used in the fcst process, not only due to the consensus in the other guidance, but to help maintain better forecast continuity--i.e. not to shift too much of the accumulation from the snow to ice category. But this is a trend that we will have to monitor in subsequent fcst shifts. We continue to expect 8-12" of snow over the climatologically coldest part of the CWA during CAD, i.e., the east-facing Blue Ridge Escarpment and area extending east along I-40. "Snow" totals have declined by a few inches over the northern GA/SC zones and in the more western NC mtns, as more of the QPF is now expected to fall as sleet. Ice accums remain at least advisory criteria along the fringe of the sleet area. Confidence is already high enough to warrant a Winter Storm Watch for all of our NC zones; one is being hoisted with this package. This is at least 12 hours earlier than we would normally issue a watch. We thus have decided to leave out all the GA/SC zones for now and perhaps try to better define the p-type transition zone. The expected sleet/ice amounts in these zones will be more sensitive to forecast QPF and therefore a downward trend could keep some areas out of warning crtieria altogether, thus not warranting a watch there. Stay tuned. WAA continues, albeit more weakly, as the sfc low pushes out to sea Sunday night. At that time we will begin a slow transition from the CAD/Miller-A forcing to that supplied by a shortwave/deformation zone transitioning over the area. PoPs decline very slowly thru Monday as a result. With the WAA, whereas we might normally expect a transition to all snow across the area, we will continue to see mixed p-types toward the south and east, wherever sfc temps remain near or below freezing. Moisture becomes more shallow during this time, too, putting the possibility of additional snow/sleet in question as ice nuclei become scarce. Impacts from the combination of what is expected to be a very wet snow, combined with icing in some areas, are not looking any less significant than what the previous shift expected, even though total amounts may have come down with this package. Very windy conditions are expected Saturday night and most of Sunday, which makes falling trees/powerlines likely.
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December 8-10, 2018 Winter Storm
BlueRidgeFolklore replied to Orangeburgwx's topic in Southeastern States
They're showing more for Salisbury than atop Mt. Mitchell. I'm sorry, but there is no on this earth that I am going to buy into that map right now. -
December 8-10, 2018 Winter Storm
BlueRidgeFolklore replied to Orangeburgwx's topic in Southeastern States
The main point is that there is ZERO guidance that even suggests it at this point.