Runman292

I know it's way too far to determine this with any sense of absolute certainty, but if the instability is sufficient, could we see something similar to April 27th?

Day 4 Outlook from the SPC: ...SEVERE WEATHER OUTBREAK POSSIBLE ON D4/SAT... ...DISCUSSION... ...Day 4/Sat - Central Gulf Coast States to the Ohio Valley... A strong large-scale upper trough is forecast to quickly move across the Plains to the MS Valley on Saturday. An intense jet streak will move across the Deep South into the OH Valley as this occurs. At the surface, a low secondary to the 980 mb low over the Upper Midwest is forecast to develop during the late morning/early afternoon across the mid-South. This will aid in further northward transport of rich Gulf moisture into portions of the Lower MS Valley and TN Valleys. Atop this moisture-primed boundary layer, cold 500 mb temperatures are forecast. This may support fairly steep lapse rates, which would foster moderate instability across portions of MS/AL amid supercell wind profiles. However, some uncertainty remains tied to the evolution of convection in the Day 3/Fri period into the morning hours of Saturday. Some forecast guidance suggests a relatively pristine warm sector will be maintained, or if only isolated convection develops overnight/early Saturday, recovery could occur. If this scenario unfolds, a concerning severe weather setup supporting all-hazard severe could unfold across portions of LA/MS/AL through the day and into evening, and eventually spreading east into GA overnight. Trends will be monitored closely over the coming days and further adjustments to the 30 percent/Enhanced risk area may be needed in future outlooks. With northward extent, instability will become more limited. Nevertheless, sufficient moisture amid intense deep-layer flow will support swaths of strong/damaging winds into the Ohio Valley and portions of the central Appalachians Saturday and Saturday night. Higher outlook probabilities may be needed in subsequent outlooks if confidence increases.

As someone who is a novice to severe weather models, which ones do I need to look at?

Excerpt from the MRX AFD in regards to severe weather on Saturday. Severe Weather: The SPC has already included most of the region within a 15% risk area for severe thunderstorms on Saturday afternoon through the overnight hours with a 30% risk area delineated to our south and west. There are several factors influencing the severe weather risk.We will be warm sectored across the region, but the surface low will be far to our north into Ontario. As a vort maxima rotates through the upper-level trough axis, a secondary surface low feature is expected to develop across the Mid-South and move northeast into the Central or Southern Appalachians. This will enhance low-level and effective bulk shear in the vicinity of this surface low feature, and this is visualized in model sounding data showing long hodographs with strong curvature near the surface low feature. The wind fields are expected to be very strong across the region, but the limiting factor to higher severe weather probabilities at this time is questions about instability. Depending on the exact upper-level trough amplification and track of the secondary surface low, instability could vary significantly. If the surface low takes a slightly westward track, we will be in a favorable thermodynamic for supercell convection on Saturday afternoon that grows into a QLCS with wind damage and tornado potential Saturday night. If this surface low features tracks more eastward, we will likely see more of a flash flooding risk with the primary severe hazards remaining to our south and east. NWP guidance (GFS,ECMWF, ensembles) continue to indicate near 1000 J/Kg of MLCAPE and EBShear above 50 kt which would support an all-hazards severe weather event. ECMWF EFI is also near 0.9 with a SOT of 1 across the region which presents at least a weak to moderate signal for significant CAPE/Shear combination. Wind damage would be the primary risk, but tornadoes, flash flooding, and large hail would also be risks to monitor - especially with any supercells. This severe weather forecast will be important to monitor over the next several days.

Interesting to see local TV mets in East TN talk about severe potential 1 week in advance. That is definitely something they don't usually do.

After February 14th, David Aldrich will no longer be doing Captain Accurate Weather in East Tennessee. He's going to Southeast VA to be the meteorologist for WTKR.

I'm at the Dollar general in the West side of Oak Ridge and I can confirm. A good dusting on the grass

A moving truck tried to go up my hill and got stuck on the hill. It took him 30 minutes of going backwards and forwards to realize that he wasn't going to get up the hill. He finally backed down the hill and went back into the turnpike.

The freezing rain has turned back into snow in Oak Ridge.

I thought I would see snow when I went out, but it's the dreaded freezing rain right now. I'm hoping it will turn back to snow soon. I thought we would have been north enough to see all snow.

It has changed from snow to freezing rain in Oak Ridge. The roads are snow and ice covered.

I have just a touch under 2 in my location in Oak Ridge.

Definitely coming down good in Oak Ridge.

I pray that everything will go well. I'm hoping that you get to enjoy the snow.

I'm in Oak Ridge, so I should be in the same boat. I'm rooting for the mix to stay more south into GA.

Looks like MRX is going all in on the western half of the Central valley, northern plateau, and Southwest Virginia getting hammered with snow.

Ladies and Gentlemen, MRX has finally joined the chat: All watches have been upgraded to warnings.

It's pretty cool to stay up all night and talk weather with everyone. I really enjoy learning a lot with these conversations.

WVLT Mets:

Could you post a map?

If you just read the bottom line, you would think that the storm is more of an inconvenience than a hazardous event.

Maybe I've missed it, but it seems like MRX never mentions models like the ICON. Why is that?

It's almost as if they saw the recent runs and were like "Yes, we have an excuse not to issue warnings!"

MRX AFD: Discussion: Bottom line up front: No change will be made to the Winter Storm Watch at this time, due to the lowered confidence in p-types and snow amounts. To issue a Warning beyond 24 hours, confidence must be high that Warning criteria will be met and that impacts will be significant. Model trends and differences: The NAM has thrown a wrench in the forecast with its depiction of a warm nose spreading well northward into our area, due to its strong southerly low level jet. This potential for mixed p-types adds much uncertainty to the forecast snow amounts in southern sections and in the lee of the mountains. The main difference in the NAM is that it develops a secondary surface low in northern AL on Friday afternoon, which tracks NE along the Cumberland Plateau to WV through the evening. This creates a strong pressure gradient across the TN mountains, and a 40-50 kt LLJ. However, it is noteworthy that this is not a typical mountain wave/downslope enhancement pattern, which is usually characterized by a 850 mb jet max to our NW, so perhaps the NAM is overdone with the downslope warming. Also, the NAM is an outlier in its solution, as the GFS and ECMWF do not develop this secondary low and LLJ, and keep warm advection to our south. The HRRR seems to be a compromise solution, and is not as aggressive with the warm nose and LLJ as the NAM. Precipitation types: At onset Friday morning, temperatures profiles will support all snow as top-down moistening evaporatively cools a dry low level layer. HREF p-type probs show a snow/sleet/fzra mix entering southern sections between 1 PM and 4 PM EST. The northward extent of this mix is a big uncertainty, but for this forecast, the HREF probs look reasonable, and keep the mix mainly to the south of I-40. The strength of the downslope wind will affect the p-type in the foothills north of I-40 and the Tri-Cities, and the potential for a brief period of mixed p-types may result in lowered snow amounts there. Snow amounts and confidence: The area of highest confidence in the snow amount forecast is north of I-40 and west of I-81, in the northern Cumberland Plateau area and KY border counties, where the p-type is highly likely to remain all snow. In this area, amounts are expected to be in the 4-6" range. As we go south and east from there, confidence lowers due to the above mention p-type issues. In the southern Valley and SW NC, 1- 3 inches of snow is expected, mainly during Friday morning and early afternoon before the mix takes over, with the potential for up to a tenth of an inch of ice accumulation in the mid/late afternoon and evening. Another factor in the snow amounts will be the loss of moisture in the dendritic growth zone from the dry slot Friday evening, which may shut off accumulating snowfall sooner than previously forecast. The chance of accumulating precip drops rapidly between 7 PM and midnight EST as the dry slot moves overhead. Freezing drizzle may be a concern during this period. Timing: Not much has changed from previous forecasts regarding the timing of snow onset Friday morning. Expect that the morning commute in the Chattanooga area could be impacted by snow, potentially starting as early as 7 AM EST but accumulating mainly in the 9-11 AM time frame as snowfall rates increase. In Knoxville, 10 AM to noon appears to be the likely time frame for snow to start accumulating, with Tri- Cities being in the noon to 2 PM window. Peak precip intensity appears to be during the afternoon, from around 1 PM EST to 7 PM EST. Precip will begin to end near or after 7 PM from SW to NE as the dry slot moves across the area and brings drying in the dendrite growth zone. This end time is faster than previously forecast, but the end time of the Winter Storm Watch will be kept at 7 AM EST Saturday. We transition to a NW flow pattern Friday night, which may result in some additional light snow accumulation in SW VA and the TN mountains into Saturday morning.