textproduct: Caribou

WHAT HAS CHANGED

* 7PM Update: Increased wave heights based on wind direction tonight into Wednesday. Extended SCA on intracoastal waters into Wednesday afternoon based on these higher seas.

* Confidence is increasing in light snow in northern and central Maine tonight into Wednesday, alongside fog development, impacting Wednesday morning commute.

* Confidence increasing in light snow NW areas/Snow-Rain mix to Rain E Aroostook/N Penobscot Wednesday night and Thursday.

* Confidence increasing in potential for flash freeze for Eastern/Central/Downeast Maine Thursday night.

* The system for Saturday night and Sunday has trended a little colder, making snow more expansive. Now a mix of rain and snow is potentially being limited to only coastal Downeast Maine.

KEY MESSAGES

1) Light snow North, light rain south, along with fog development overnight, that could impact the Wednesday morning commute.

2) Snow possible Wednesday night and Thursday northwestern areas, a rain/snow mix changing to rain over northeastern Maine and rain elsewhere. This could impact the morning and evening commutes on Thursday.

3) Arctic air will filter into the area Thursday night into Friday bringing abruptly colder conditions and possibly icy roads.

4) Snow is possible Saturday night and Sunday over Mainly Eastern Maine, except for a rain/snow mix being possible coastal Downeast. This could impact travel on Sunday.

DISCUSSION

KEY MESSAGE 1... Light snow North, light rain south, along with fog development overnight, that could impact the Wednesday morning commute.

KEY MESSAGE 1 DESCRIPTION... Low pressure over to the west begins to move northeast, bringing a warm front across the region tonight, advecting some warm air into the area for tomorrow. Lift provided by the front helps to drops some snow overnight over the region, predominantly in the north and central regions. Downeast and coast should be warm enough for all precipitation to be rain. Generally looking at about an inch or two in terms of accumulations in the north. Cold snowpack and advection of warm air will help cause fog to develop around the region tonight. Snow expected to be comparatively wet. Snow moves out of the region by Wednesday morning.

KEY MESSAGE 2... Snow possible Wednesday night and Thursday northwestern areas, a rain/snow mix changing to rain over northeastern Maine and rain elsewhere. This could impact the morning and evening commutes on Thursday.

KEY MESSAGE 2 DESCRIPTION...

Vertically stacked low pressure system to the west approaches Wednesday night, bringing a period of rain Downeast, as a rain/snow mixed precipitation transition line forms from roughly Greenville to Presque Isle. North of this line, will be snow. Warm air advection ahead of approaching frontal system, results in patchy fog development throughout the region, especially as surface remains cold due to steady snow pack. Anticipating roughly half an inch to an inch across the northwest and far north Wednesday night into Thursday morning.

A full latitude trough approaches from the west Thursday, then begins to build into Maine Thursday evening, as a surface low tracks across Maine, then into the Maritimes Thursday evening. This will allow for mild air to build in to the south of the low, causing mainly rain across Downeast Maine, the Bangor/Penobscot Region and S Piscatiquis County, with snow changing to Rain across N Penobscot/SE Aroostook and snow mixing with or changing to rain over NE Aroostook Thursday morning. The precipitation should end as a period of snow showers over the North before ending Thursday evening. 1-3" of snow is possible over N Aroostook/Piscatiquis/Somerset with less than an inch possible across the remainder of the North. There is still some uncertainty on the exact track and strength of this system, so the exact dividing point between all snow/all rain and a snow/rain mix and snowfall amounts likely will change. A moderate snowfall over mainly the AS CHANGED... Confidence is increasing North Woods cannot be ruled out at this time. Highs on Thursday should range from the lower 30s to upper 30s across the North and from Around 40 to the lower 40s elsewhere, this is 10-15 degrees above normal. West winds could gusts 20-30 mph Thursday afternoon. Temperatures fall off Thursday afternoon, most notably over NW areas where they fall into the mid teens to around 20 by evening.

KEY MESSAGE 3... Arctic air will filter into the area Thursday night into Friday bringing abruptly colder conditions and possibly icy roads.

KEY MESSAGE 3 DESCRIPTION... The axis of a full latitude trough crosses the area late Thursday night, then exits to the east Friday, as northern stream shortwave ridging builds in. This will allow for Canadian high pressure to build in immediately behind a strong cold front Thursday night and Friday. The greatest fall off in temperatures should occur Thursday evening in most locations with temperatures from the mid single digits to mid teens across the North and mid teens to mid 20s elsewhere by around midnight and wind chills to the single digits below zero to the single digits above zero across the North and mid single digits to mid teens elsewhere. This rapid fall of temperatures could cause a flash freeze of any untreated surfaces Thursday evening, making the evening commute dangerous. Lows Thursday night bottom out from around 5 below to around 10 above which is near to a few degrees below normal. Temperatures only rise to the mid teens to around 20 across the North on Friday and lower 20s to around 30 elsewhere.

In addition to the potential flash freeze, there could be some strong snow showers possible with the passage of the front Thursday evening.

KEY MESSAGE 4... Snow is possible Saturday night and Sunday mainly over Eastern Maine, except for a rain/snow mix being possible coastal Downeast. This could impact travel on Sunday.

KEY MESSAGE 4 DESCRIPTION... A northern stream shortwave lifts northeast from the Great Lakes Saturday night, followed by a northern stream trough moving into eastern Quebec on Sunday. This will support a broad area of low pressure crossing Saturday night and Sunday. This could bring periods of snow Saturday night and Sunday over mainly Eastern Maine, with a mix at this time appearing to be limited to coastal Downeast Maine. At this time, there is still quite a bit of uncertainty on the exact track, strength and timing of this system, so the impacts, beyond the potential impact to travel on Sunday, and an estimate of snowfall are not reasonably predictable at this time.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

Tonight through Wednesday: VFR/MVFR due to low cloud ceilings from approaching frontal system to the west. Light SE to S winds this evening. Light snow possible in the north overnight, with gusts back up to the 15-20 kts range by daybreak on Wednesday. Ceilings will drop down to MVFR/IFR heights after midnight for northern terminals, and approach low end VFR/high end MVFR for BGR and Downeast terminals overnight. Potential for fog development on Wednesday, reducing visibility that could begin to dip towards MVFR. Marginal chance of LLWS between around midnight and sunrise overnight tonight, depending on how strong of a surface inversion develops and how high surface winds and gusts become overnight.

Wednesday night...IFR, possibly lowering to LIFR. Winds light and variable.

Thursday: IFR or lower probable, probably becoming VFR at southern terminals in the afternoon. Sw-WS winds G15-20KT possible in the afternoon.

Thursday night: IFR or lower possible at northern terminals in the evening, becoming VFR throughout. WSW-W wounds G15-25KT probable.

Friday: VFR. WSW-SW winds G15-20KT possible.

Friday night-Saturday: MVFR possible in snow showers. SW winds G15-30KT possible Friday evening and again Saturday morning.

Saturday night-Sunday: MVFR or lower possible in snow, except rain/snow mix possible KBHB. S-SW winds G15-25KT possible.

MARINE

Small Craft Advisory conditions over the coastal waters starting tonight, adding in the intra-coastals later tonight. SW winds will increase tonight into Wednesday. Seas gradually rise to 6 to 10 ft over the coastal waters Wednesday. There is a chance of rain and fog tonight into Wednesday which could limit visibility.

SCA conditions are possible on the coastal ocean waters Thursday morning, with gales then possible on the coastal ocean waters from Thursday afternoon through Thursday night, with SCA conditions probable on the intra-coastal waters. Will highlight this gale threat in the HWO. SCA conditions likely on all waters Friday and Friday night. The SCA conditions could then continue on the coastal ocean waters through the weekend, mainly for seas. Sub-SCA conditions are currently forecast on the intra-coastal waters for the weekend.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory until 1 AM EST Thursday for ANZ050-051. Small Craft Advisory from midnight tonight to 2 PM EST Wednesday for ANZ052.