textproduct: Caribou

WHAT HAS CHANGED

-Updated aviation section to reflect 12z TAFs

-Issued a winter weather advisory for all of northern and Downeast Maine from 6 AM Saturday until 1 PM Saturday

-Increasing confidence in mid-week storm, with at least a mix of snow and rain precip types.

KEY MESSAGES

1) A wintry mix is expected Saturday morning and could result in some minor travel difficulties on untreated surfaces.

2) Temperatures rise well above normal through the middle of next week, likely leading to significant snow melt and river/lake ice rot.

3) Another storm may cross the region on Wednesday, with a possibility for rain, snow, and even a chance for wintry mix.

DISCUSSION

KEY MESSAGE 1... A wintry mix is expected Saturday morning and could result in some minor travel difficulties on untreated surfaces.

KEY MESSAGE 1 DESCRIPTION... Moisture will continue to gradually increase tonight in advance of an approaching warm front. Warm advection aloft will result in a wintry mix of sleet and freezing rain developing toward daybreak Saturday morning. Guidance has trended slower with the precipitation onset, so it looks like the steadier precipitation will hold off until around sunrise Saturday morning, although it could begin a bit earlier across the western zones.

A Winter Weather Advisory has been issued beginning early Saturday morning through early Saturday afternoon for all of northern and Downeast Maine, except the coast. By afternoon, temperatures at the surface should have warmed enough that precipitation changes to all rain.

Freezing rain accumulations are expected to range up to one-tenth of an inch across the north and around a trace across interior Downeast areas. Little if any sleet accumulation is expected. Some minor travel difficulties are possible on untreated road surfaces early Saturday morning.

KEY MESSAGE 2... Temperatures rise well above normal through the middle of next week, likely leading to significant snow melt and river/lake ice rot.

KEY MESSAGE 2 DESCRIPTION... A mild air mass remains in place over the forecast area through the first half of the upcoming work week, with a split stream flow as the polar jet remains north of our area and the subtropical jet sits south of the region. This synoptic setup will keep disturbances away for the most part, and allow for the mild air mass to continue to sit over northern New England and for temperatures to gradually rise into the middle of the week. This rise in temperature could lead to high temperatures lifting into the low to mid 50s throughout the CWA, and lows each night falling into the upper 20s to mid 30s.

These temperatures will significantly erode the existing snow pack, with as much as a half an inch to an inch of SWE loss. Currently, SWEs across the forecast area sit around 1 to 4 inches. Some areas could see a complete loss of snow pack with this pattern, particularly closer to the Downeast coast and around the Bangor area. But even areas with a greater snow pack in the higher terrain of the north could see significant reduction in snow depth. These warm temperatures will likely lead to river and lake ice beginning to rot as well.

KEY MESSAGE 3... Another storm may cross the region on Wednesday, with a possibility for rain, snow, and even a chance for wintry mix.

KEY MESSAGE 3 DESCRIPTION... The polar jet will dip southwards on Wednesday and help usher in the next shortwave out of the Central Plains and Ohio River Valley, carrying the low up into our CWA from the SW. Current guidance suggests the low will arrive as an open wave, but the exact position of the trough axis aloft as this system moves into the area remains uncertain, leading to continued uncertainty in the exact track of the low. The storm track will have a large influence on precipitation type through the middle of the week. If the trough axis remains further north and the center of the low follows the St. Lawrence River, the CWA could entirely enter the warm sector of the low, with more rain in the forecast. But if the pattern remains progressive, the low could track across the Downeast region, with a colder outcome across the forecast area and more snow in the forecast. Should the warm front lift through the area, especially if the trough is in just the right place near the northern edge of our CWA, there could be a period of wintry mix once more with this setup. That said, at this time range, this threat is still very uncertain, and for now the forecast remains for a mix of rain and snow. This system will continue to be closely monitored over the next several days.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

VFR/MFVR ceilings are expected through this evening. Expect a wintry mix of sleet and freezing rain to begin to overspread the terminals, mainly 09z to 12z Saturday. MVFR/IFR is expected Saturday afternoon in rain, patchy fog, and low ceilings. E to NE wind 5 to 10 kt today, then light SE tonight. S wind 5 to 10 kt Saturday.

Sat night - Sun...Gradual improvement to VFR. SW winds shift W 5 to 10 kts with gusts to 20 kts, tapering off through the day on Sunday.

Sun night - Mon...VFR across all terminals. SW winds 5 to 15 kts with gusts to 25 kts.

Mon night - Tue...VFR across all terminals with SKC spreading throughout the region. SW winds shift W 5 to 10 kts with gusts to 20 kts.

MARINE

A small craft advisory remains in effect for the outerwaters through this evening. Winds/seas will then increase toward small craft levels by Saturday afternoon.

Southwest gales are possible Saturday night into early Sunday across the coastal waters as a cold front crosses the waters. Winds will begin to taper off through the day on Sunday, however seas will likely remain around 5 ft through the rest of the weekend and into the early part of next week. Winds could increase once more on Monday, with gusts returning to around 25 to 30 kts through the first half of the week. Air temperatures will be mild enough for no threat for freezing spray during this time.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Winter Weather Advisory from 6 AM to 1 PM EST Saturday for MEZ001>006-010-011-015>017-031-032. MARINE...Small Craft Advisory until 7 PM EST this evening for ANZ050- 051.