textproduct: Caribou

WHAT HAS CHANGED

-Updated aviation section to reflect 0Z TAFs

previous -Expanded frost advisory further south from Dover-Foxcroft to Topsfield.

-Added key message about unsettled weather next week.

KEY MESSAGES

1) Near to below freezing temperatures are expected over the north again tonight, leading to widespread frost, especially in colder valleys. This may lead to damage to sensitive vegetation.

2) Widespread soaking rain likely from Sunday night into Memorial Day. This could help aid in mitigating on going drought conditions across portions of the region.

3) Continued unsettled weather through the week with multiple systems coming into the area.

DISCUSSION

KEY MESSAGE 1...Near to below freezing temperatures are expected over the north again tonight, leading to widespread frost, especially in colder valleys. This may lead to damage to sensitive vegetation.

KEY MESSAGE 1 DESCRIPTION... Another round of frost and freeze conditions is expected across northern Maine tonight as high pressure crests over the area. The combination of a cold air mass and favorable radiational cooling conditions will likely cause temperatures to fall below most guidance again. Opted to take the low temps reached this morning and blended them with the NBM 10th percentile to bring them up by a degree or two given the airmass has moderated some today. Frost advisory has been issued for areas north of a Dover-Danforth line but the frost/freeze program is not active across portions of northwestern Maine. However many of these areas will see another round of below freezing temperatures by morning.

Models continue to slow down progression of the axis of deep layered ridging to the east this weekend. This should once again allow for decent radiational cooling conditions Saturday night. Given NBM warm bias when there is strong radiational cooling, used a blend of NBM10/NBM for lows Saturday night. This should allow for areas of frost across Northern Aroostook overnight and will continue to be a threat to sensitive vegetation.

KEY MESSAGE 2...Widespread soaking rain likely From Sunday night into Memorial Day. This could help aid in mitigating on going drought conditions across portions of the region.

KEY MESSAGE 2 DESCRIPTION... The exiting of the deep layered ridge axis to the east late Sunday, allows for strong low level warm advection to set up Sunday night and to continue into Memorial Day. At the surface, high pressure slowly exits to the east, with a cold air damming signature over the region, that is reinforced by a surface low tracking across the Gulf of Maine on Memorial Day.

As a result, rain develops from SW to NE Sunday night. Then tapers off from SW to NE Monday afternoon as the coastal low exits to the southeast.

This system should bring widespread wetting rain to the region from Sunday night into Memorial Day, with the potential for up to 2/3 inch of rainfall along the coast. The rainfall coupled with the cold air damming should result in Monday being cooler than Sunday, with highs mainly in the mid to upper 50s.

KEY MESSAGE 3...Continued unsettled weather through the week with multiple systems coming into the area.

KEY MESSAGE 3 DESCRIPTION... A strong upper level ridge over the center of the country will throw multiple shortwaves into our area over the next week. The ridge will reach all the way into northern Canada, while our area will be on the trough side of this pattern. This will bring multiple rounds of rain through the week. Models differ on the exact timing of each of these rounds, which will depend on the strength and position of this pattern.

AVIATION /00Z SATURDAY THROUGH WEDNESDAY/

Tonight through Sat Night...High confidence in VFR through the period. Light N wind through Sat, except becoming S around 10 kt at KBGR/KBHB Sat afternoon. Light S wind Sat night.

Sunday...Mainly VFR. S winds 5-15kts.

Sunday night...IFR or lower conditions likely develop by late Sunday night as rain moves in. Fog possible at southern terminals. LLWS possible. Winds 5-10 from the south shifting to south east, gusting to 20 kt.

Monday...MVFR/IFR conditions due to rain. Winds SE at 5-10 kt gusting to 15 kt, becoming light and variable in the afternoon.

Monday night-Tuesday...VFR, except for a brief period of MVFR possible Tuesday afternoon in any stronger showers at northern terminals Tuesday afternoon. W winds G15KT possible Tuesday afternoon.

Tuesday night-Wednesday...MVFR as rain spreads into southern terminals.

MARINE

Seas and winds remain well below small craft advisory levels. Sea surface temperatures remain in the middle 40s and are conducive to hypothermia to anyone immersed in the waters.

A fairly relaxed pressure gradient over the waters Saturday night and Sunday should limit winds to 10 kt or less and seas to 2 ft or less. SCA conditions are possible over the coastal ocean waters Sunday night into Monday night, with sub-SCA conditions over the intra-coastal waters. On the outer waters Sunday night and Monday, there should be wind gusts up to 25-30KT and seas up to 8 ft. While winds subside Monday night on the outer waters, seas could remain up to 6 ft. A relaxed pressure gradient returns to the waters on Tuesday, with winds 15 kt or less and seas 4 ft or less on the coastal ocean waters and 5 ft or less on the outer waters. Winds and waves remain below SCA conditions Wednesday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Frost Advisory from midnight tonight to 7 AM EDT Saturday for MEZ002-005-006-010-011-031-032. Beach Hazards Statement from Saturday morning through Saturday evening for MEZ029-030. MARINE...None.