textproduct: Caribou

WHAT HAS CHANGED

- Updated the aviation section to reflect the 12z TAFs

- Increased confidence in occluded front and inverted trough placement for Tuesday night into Wednesday

- Increased snow amounts slightly for Downeast for the mid-week snow storm

KEY MESSAGES

1) Light to moderate snow likely early Wednesday morning, with the best chance for snow Downeast. Snow could impact the Wednesday morning commute.

2) Another round of snow possible Saturday across the north, accompanied by warming temperatures lifting to at or above freezing through the forecast area.

DISCUSSION

KEY MESSAGE 1... Light to moderate snow likely early Wednesday morning, with the best chance for snow Downeast. Snow could impact the Wednesday morning commute.

KEY MESSAGE 1 DESCRIPTION... An occluded low pressure system will move into the area Tuesday night, with a trough of low pressure setting up from northwest to southeast across the forecast area through the day on Wednesday. This broad area of forcing will lead to the next widespread chance for snowfall in the forecast area. Highest snow totals will likely be confined to the Downeast region where moisture is more available along this region of forcing. There is increased confidence that the initial occluded low/occluded front will bring snow to our area, particularly Downeast, and so have brought in definite PoPs to the Bangor and Downeast areas with likely elsewhere. The northern half of the forecast area, and particularly up into the St John Valley, is least likely to see much in the way of accumulating snow.

As the vorticity max aloft begins to exit the area late on Wednesday, a surface inverted trough will likely linger behind the departing low and extend up through the state into Wednesday night. There is increased confidence in the existence of this inverted trough, though the exact placement does still vary slightly from run to run and model to model. Across the board, there seems to be converging solutions placing the norlun trough in southern Maine, just west of our forecast area. That said, there are still many solutions that place the trough on the CWA border or even centered over the Bangor area. A slight shift within this 100 mile swath could be the difference maker for what area sees 4 to 6 inches of snow versus only a couple of inches total.

KEY MESSAGE 2... Another round of snow possible Saturday across the north, accompanied by warming temperatures lifting to at or above freezing through the forecast area.

KEY MESSAGE 2 DESCRIPTION... A very strong 500 mb vorticity max originating over Newfoundland through the middle of the week may retrograde through the end of the week and dive back south over the forecast area this weekend. This pattern could lead to enough instability for snow showers, particularly across the northern half of the forecast area. For the time being, it appears the limiting factor for this system will be moisture availability, and current global guidance suggests light QPF with this event, leading to light snow totals. This low pressure system will have arctic connections instead of tapping into the Gulf Stream, so this will not help support stratiform moderate to heavy snowfall. That said, steep low level lapse rates could combine with a tighter pressure gradient aloft to generate convective snow showers that may limit visibility or impact travel during the day on Saturday. A warming trend is in store for behind this low, with temperatures lifting above normal, and potentially above freezing, across the entire forecast area.

AVIATION /12Z MONDAY THROUGH FRIDAY/

Mainly VFR through Tuesday. Temporary MVFR ceilings this morning at the Aroostook county terminals. NW wind today 10 to 20 kt with gusts to 30 kt at times this afternoon. NW wind 5 to 10 kt tonight through Tuesday. LLWS at KBGR/KBHB through this afternoon.

Tuesday night - Wednesday: VFR early, tending towards MVFR/IFR cigs from south to north in snow. Winds light and variable overnight, becoming N at 5 to 10 kts Wednesday afternoon.

Wednesday night - Thursday night: Northern terminals will quickly improve to VFR, while BGR/BHB may linger in MVFR/IFR in lingering snow through Wednesday night before improving to VFR/MVFR during the day on Thursday. NW winds 5 to 10 kts with a few gusts to 20 kts possible.

Friday - Friday night: VFR across all terminals. NW winds 5 to 10 kts.

MARINE

The gale warning for the outer waters has been extended through 10 AM EST for frequent gusts of 35 kt. Winds will then decrease to SCA levels this afternoon through Tuesday. The SCA for the intra coastal zones remains in effect through 5 PM EST.

Wind gusts will increase towards 25 kts on the coastal waters Wednesday night as a low pressure system deepens south of the waters. These wind gusts could persist through the end of the week. Seas will generally remain at or below 4 ft through the rest of the week. Light freezing spray is possible early Thursday morning on the intracoastal waters and then again Friday morning across all waters.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Gale Warning until 10 AM EST this morning for ANZ050-051. Freezing Spray Advisory until 10 AM EST this morning for ANZ050>052. Small Craft Advisory until 5 PM EST this afternoon for ANZ052.