textproduct: Caribou

WHAT HAS CHANGED

- Added fog and drizzle this morning across much of the Central Highlands to Downeast coast.

- Increased precipitation totals today in response to PWATs climbing to 2.5-3.5 sigma.

- Increased snow totals in locations above 1000ft elevation tonight into early Monday AM.

- Increased rain/snow shower coverage for Monday.

KEY MESSAGES

1) Widespread soaking rain today will briefly end as snow tonight across mainly northern regions with light accumulations. Black ice possible for Monday AM commute as temperatures fall below freezing.

2) Unseasonably cool temperatures expected mid to late week with no big storm systems expected.

DISCUSSION

KEY MESSAGE 1...Widespread soaking rain today will briefly end as snow tonight across mainly northern regions with light accumulations. Black ice possible for Monday AM commute as temperatures fall below freezing.

KEY MESSAGE 1 DESCRIPTION... Setup...A strong parent low tracking well north of the region today will drag an occluded front into Maine later today. Ahead of the front in response to a digging 500mb trof will be a 90-110kt jet streak leading to an enhanced area of upper level divergence which increases surface convergence along and ahead of the front. PWATs ahead of the front today climb to +2.5 and +3.5 sigma which is 1-1.3 inches. A warm front will lift into the Gulf of Maine and a surface low develops along a triple point which will aid in the surface lift across Maine. Expecting widespread rainfall to result from the surface lift and very high PWATs compared to climo.

Rainfall and Rivers...Intially this morning expecting drizzle and fog across the Central Highlands, Bangor Region to Downeast coast with the light flow off the Gulf of Maine and moist boundary layer. This morning widespread rain pushes from western Maine and expands in coverage. Expect the bands of rain moving SSW to NNE across the area. Expecting widespread accumulations of 0.5-0.75 inch across the CWA today as a result. Area rivers and streams will continue to rise. Across the North Woods and along Route 11 there remains snowpack melting with up to 4 inches of SWE. As a result of melting snowpack and recent rains the St. John River at Fort Kent gage is currently into Action Stage above 18ft with latest flow of 85700cfs. Latest HEFS, NAEFS and GEFS for the FTKM1 gage peak the flow around 90000cfs well below flood stage. However, at 18ft stage we do see water getting into basements of some houses and structures upstream of the St. John River along the Fish River due to backwater rises. Additionally, agricultural fields between Fort Kent and Upper Frenchville along Route 1 and fields along Route 161 between St. John Plantation and Fort Kent become inundated. Lastly, due to a frost remaining in most areas across Northern Maine expect much of the water to runoff into rivers/streams/creeks. This may result in high water along area roadways, culverts potentially impacting the integrity of the roads. Otherwise, no other areas across the CWA do we expect flooding concerns as streamflows continue to rise. In most areas from the Central Highlands to Downeast Maine this is welcoming rain for the ongoing groundwater drought.

Thunder...Hi-res CAMs along with ECMWF/GFS continue to show an area of 100-150j/kg of MUCAPE developing this afternoon ahead of the weak sfc low developing. Cannot rule out some elevated embedded thunderstorms along the Downeast Coast and out over the Coastal Waters. Snowfall...Later this afternoon into the evening with steady precipitation ongoing expect FROPA to take place. Temperatures will quickly cool aloft with much colder air working in thanks to the 500mb trof. Temperatures will gradually cool down the column and turn precipitation from rain to snow at first across the North Woods then eastward for the rest of Northern and North-Central Maine. Rain and snow will mix and eventually change to snow including into the Caribou to Houlton regions. The best chance of accumulations will be at elevations >750ft but cannot rule out a dusting on grassy cold surfaces in the Route 1 corridor north of Houlton. Above 1000ft which is large portions of the North Woods cannot rule out 1-3 inches with generally a dusting up to 1 inch elsewhere.

Temperatures and Black Ice...Late tonight into tomorrow morning temperatures fall back into the mid to upper 20s for the Central Highlands, I-95 corridor north of Bangor and all of Northern Maine. Untreated wet surfaces may briefly become slick with black ice for the Monday AM commute. Cannot rule out black ice on portions of The Airline (Route 9) between Bangor and Wesley before sunrise on Monday. Quickly as the sun comes up expect any ice to melt with the warm/strong April sun angle.

KEY MESSAGE 2... Unseasonably cool temperatures expected mid to late week with no big storm system expected.

KEY MESSAGE 2 DESCRIPTION... An upper level trough of unseasonably cool air will dominate through mid week. Afternoon high temperatures will be a few degrees below normal for this time of year. Although a few showers are possible at times mid week, no big storm systems are expected to affect the region. Minimum afternoon relative humidity values are expected to be the lowest on Tuesday, generally ranging from 25 to 30 percent. Fortunately, winds are expected to be on the light side to help mitigate any fire weather concerns.

AVIATION /07Z SUNDAY THROUGH THURSDAY/

Through 12z This AM...MVFR north becoming IFR, IFR south becoming LIFR. IFR/LIFR due to BR/-DZ. SE winds 10-15kt with gusts to 25kt north and gusts up to 15kt south. LLWS likely north terms.

Today...IFR/LIFR. Rain. Rain mixing with snow late north. South winds 10 to 15 knots, becoming west/northwest.

Sunday night...MVFR/IFR. Rain changing to snow north. Rain Downeast. Northwest winds 10 to 15 knots. LLWS likely at southern terms.

Monday...Mainly VFR, with a low chance for periods of MVFR or lower in any snow showers at northern terminals. NW winds G15-20KT possible Monday afternoon.

Monday night through Tuesday night...Mainly VFR.

Wednesday through Thursday...MVFR possible in sct showers.

MARINE

Rain and fog will reduce vsby less than 1nm at times today into tonight, vsby improves tomorrow AM. A Small Craft Advisory is in effect from 7PM this evening till 6AM Monday for NW winds 10-20kt gusting up to 30kt and seas 3-5ft. Winds amd seas are expected to remain below headline criteria through mid to late week.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory from 7 PM this evening to 6 AM EDT Monday for ANZ050-051.