textproduct: Caribou

WHAT HAS CHANGED

- Have extended the Small Craft Advisory through 6 AM.

KEY MESSAGES

1) Moderate rain is likely across the north Friday afternoon into Friday evening with up to a half inch possible in some areas.

2) Another widespread rainfall is likely later Sunday night into Monday. Much warmer temperatures will increase potential for ice breakup on northern rivers next week.

DISCUSSION

KEY MESSAGE 1...Moderate rain is likely across the north Friday afternoon into Friday evening with up to a half inch possible in some areas.

KEY MESSAGE 1 DESCRIPTION... Low pressure will push into the area Friday afternoon as increased moisture continues to advect north over the region behind high pressure to our southeast. Dynamic lift ahead of an approaching trough will combine with strong frontal converge to produce bands of rain over the area, mainly north, Friday afternoon into Friday evening. Some moderately heavy downpours are possible. Both the NAM and the HRRR are advertising as much as three quarters of an inch over some northern spots. These solutions may be on the higher end of the forecast models. However, given the strong convergence and available moisture, up to a half inch of rain seems likely over some locations with more widespread amounts closer to a third of an inch. A bit less rain will fall Downeast where a tenth to a quarter of an inch is expected. Rainfall across the north, combined with the melting of what remains of the snow and sleet pack, may result in some ponding of low lying areas and rises of small streams late Friday or Friday night. Rain should move away to the east after midnight Friday night, possibly ending as a brief period of snow or snow showers. A surge of moderately cooler air will follow on gusty northwesterly winds.

KEY MESSAGE 2...Another widespread rainfall is likely later Sunday night into Monday. Much warmer temperatures will increase potential for ice breakup on northern rivers next week.

KEY MESSAGE 2 DESCRIPTION... Low pressure passing across the Hudson Bay Sunday night will bring a warm front through the area, along with a surge of precipitable water values around 1 inch, leading to a period of light to moderate rainfall later Sunday night into Monday. Probabilities for greater than 1 inch of rainfall are very low to none, with most ensemble and deterministic guidance favoring around a half inch of QPF over a majority of the forecast area.

A prolonged period of above freezing temperatures is anticipated behind the warm front through the middle of the week, with above freezing temperatures Monday morning through at least the middle of the week. While rainfall amounts alone are unlikely to initiate river ice breakup, the prolonged above freezing temperatures, even at night, combined with daytime highs in the 50s will be enough for increasing breakup potential over rivers such as the Allagash, Aroostook, and Saint John where ice remains. Fortunately ice on these rivers has rotted in place from the sides, top, and bottom over the last couple weeks, which combined with low river levels should mitigate potential impacts from ice jams. Nonetheless, those with interests along the Allagash, Saint John, and Aroostook Rivers should closely monitor potential for ice jams next week, particularly any spots that are most vulnerable each spring.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

Tonight...VFR. Some SW LLWS at 2K ft around 45kt. S winds 10 to 15 kt gusting to 20 kt.

Friday...VFR, dropping to MVFR over the north around midday, then IFR over the north and MVFR across the south late in the day. SSW winds 5 to 10 kt. Gusts to 20kt possible at Downeast terminals.

Friday night...IFR, improving to MVFR over the north and VFR over the south late at night. Light winds shifting NW around 5 to 10 kt.

Saturday: MVFR ceilings across northern terminals, becoming low VFR late. VFR elsewhere. NW winds 10 to 20 kts with gusts up to 30 kts.

Saturday night to Sunday: VFR. NW winds 5 to 15 kts.

Sunday night to Monday: VFR early, becoming MVFR/IFR with RA, possibly starting as a brief period of SN at northern terminals. S winds 5 to 10 kts with gusts to 20 kts.

MARINE

Winds will diminish Friday, then possibly reach SCA over the offshore waters again Friday evening. Seas will run 3 to 4 ft through Friday then increase to near 5 ft late Friday night.

A few gusts towards Small Craft Advisory thresholds are possible Saturday into Saturday evening. Winds and seas below advisory thresholds are expected later Saturday night through Sunday. Gale force winds are possible Sunday night into Monday, along with low visibility in rain.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory until 6 AM EDT early this morning for ANZ050-051.