Second call for Thu N - Fri snow/ice

Water equivalent: No changes in my thoughts. Expecting .3" to .6" of water, mainly in a three hour period early Friday morning. NWS: .38" to .44".

Timing: Notable differences on the NAM and GFS. GFS still brings up to .25" water in by 7am, while the NAM has only trace amounts, and has main focus of precip after 7am. Interestingly, the NWS is fairly quick bringing precip in, having >/=80% POPs in by midnight, and .22" to .28" of water by 6am - in line with GFS, and ends likely precip by 9am. My current thinking is a blend of the NAM and GFS but a little lean on the GFS since the NAM has been underperforming lately. Precip starting by 2am, focus time between 5am and 8am, likely precip done by 10am.

Ptype and ratios: First, changes in the timing of the storm will affect ptype signficantly. Right now, the NWS has this as a primarily nocturnal storm during the time of minimum daytime heating, and has an all snow event now. Surface temperatures are not expected to rise above freezing before 11am, so should be all wintry mix until then, and after 11am, precip will be wrapping up anyway (per both models). The projected track of the mid level low has shifted a little east, which would open up the possibility of less mid level warming, however the models have been slightly underestimating the strength of the low, which could end up taking a route slightly west of the current forecast. What is definite: all snow through 6am. After 6am, depending on the strength of WAA in the mid levels, could see mixing with sleet, and a period of freezing rain, but not as long as was previously expected. As for snow to water ratios, a period of great dendritic growth will assist in keeping snow levels above 10:1, however once WAA kicks in, while precip rates will increase, ratios may drop to around 10:1. Overall expecting around 11:1 ratios.

Second call:
Snow accumulation: 2" - 3.5"
Ice accretion: T - .1"

--- Snowday Outlook ---
Support of the NAMs timing from the NWS would yield a very high likelihood of a delay, with very low cancellation percentages. GFS timing would give a much lower chance of a delay, and a slightly higher cancellation percentage. The fact that precip wraps up early will have a significant effect, however with surface temperatures below freezing through 11am, roads will not clear off easily. I'll raise delay percentages, while dropping cancellation percentages slightly.