textproduct: Caribou

WHAT HAS CHANGED

- 8:31PM UPDATE...Have upgraded the Gale Watch to a Gale Warning for the Waters 25-60nm offshore. SW winds around 25kt and gusts up to 35kt and seas 8-11ft expected 4PM Tuesday till 3AM Wednesday.

KEY MESSAGES

1) Isolated to scattered afternoon thunderstorms Tuesday, mainly across northern areas, could be accompanied by isolated stronger wind gusts.

2) A widespread rainfall is expected late Tuesday night through Wednesday night, which will continue to improve the long term drought.

DISCUSSION

KEY MESSAGE 1... Isolated to scattered afternoon thunderstorms Tuesday, mainly across northern areas, could be accompanied by isolated stronger wind gusts.

KEY MESSAGE 1 DESCRIPTION... Short wave trough exits into the Canadian Maritime Provinces late this afternoon. Any lingering showers with this feature will quickly dissipate by sunset. Ridging builds back in tonight giving way to mainly clear skies.

Upper level pressure across central Canada slowly moves east Tuesday and Tuesday night. A broad southwest flow can be expected across the area ahead of a slow moving frontal boundary approaching from the west. This will allow temperatures to climb to well above normal levels, with highs in the lower 70s expected across much of the area, except for Downeast areas where the cooler ocean waters will keep temperatures from getting quite as high.

Expect showers with isolated/scattered thunderstorms to develop from west to east Tuesday afternoon, mainly from the Katahdin region north and west. Dew points are only expected to only be in the upper 40s to around 50 degrees, but cold temperatures aloft will promote steeping lapse rates and some destabilization during the afternoon (with capes generally 500J/kg or less). Rather strong southwest flow and deeper mixing may result in some isolated stronger wind gusts in any storms that develop in the afternoon. Note that the Storm Prediction Center has outlined a marginal risk for severe storms across portions of northern and western Maine.

KEY MESSAGE 2... A widespread rainfall is expected late Tuesday night through Wednesday night, which will continue to improve the long term drought.

KEY MESSAGE 2 DESCRIPTION... An upper level trough over the southern Hudson Bay will direct a band of Gulf moisture towards the Saint Lawrence Valley and into Maine late Tuesday into Tuesday night. Convergence and moisture pooling ahead of a cold front is expected. As the cold front moves south into the area late Tuesday night and Wednesday, south winds increase, enhancing isentropic lift as the warmer, moist air moves over the low level frontal surface. At the same time, the left exit region of a strong subtropical jet streak will approach the area Wednesday evening, while the right entrance region of a weak polar jet streak to the north remains over the area. This will cause the precipitation shield to expand and intensity to increase, with moderate rainfall rates possible. Wednesday afternoon and Wednesday night. The heaviest QPF appears focused over the northern and central portion of the forecast area where the most persistent rain band will develop. Areas farther to the south will have less QPF as they remain within the drier warm sector longer before the strengthening surface low reflection of the subtropical jet moves over these areas Wednesday night, leading to a transient burst of light to moderate rain. Elevated instability and strong dynamics may lead to a thunderstorm over the coastal waters and coastal areas Wednesday night. A general 1 to 2 inches of rainfall is expected across northern and central areas, with around or just below an inch for Bangor and Downeast Maine. This rainfall will add to the short term rainfall surplus, helping to mitigate the long term drought. No significant flooding issues are expected, but some ponding of water is possible, particularly where heavier rainfall rates occur. Rain will taper off early Thursday with some lingering showers possible and partial clearing.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

00z TAF UPDATE...

Tonight...VFR. W to SW wind 5 to 10 kt. LLWS expected to develop in the early Tuesday AM hours.

Tuesday...VFR, except MVFR possible in afternoon showers and isolated/scattered thunderstorms at the Aroostook terminals. Added PROB30 for the northern terms for the -TSRA potential. S to SW wind 10 to 20 kt with gusts 30 kt. Low level wind shear expected.

Tuesday night...MVFR, IFR possible KBGR/KBHB. S to SW wind 10 to 15 kt.

Wednesday...Predominantly MVFR with areas of VFR and IFR. -RA. S winds 5 to 15 kts, strongest south where gusts up to 25 kts are possible. LLWS possible, mainly south.

Wednesday night: IFR or lower with -RA/RA. S winds 5 to 15 kts. LLWS possible, mainly south.

Thursday to Thursday night: MVFR with -SHRA, becoming VFR. NW winds 5 to 15 kts, becoming light in the evening.

Friday: VFR, with a chance of MVFR at northern terminals. Showers, mainly north. Slight (10 percent) chance of a thunderstorm. Any storms may contain small hail and briefly gustier winds. NW winds 5 to 10 kts with gusts to 20 kts.

Friday night: VFR. WSW winds 5 to 10 kts.

Saturday: VFR with a chance of -SHRA. SW winds 5 to 10 kts with gusts to 20 kts.

MARINE

UPDATE...Gale Watch has been upgraded to a Gale Warning from 4PM Tuesday till 3AM Wednesday for ANZ080-081.

Previous Discussion... A Small Craft Advisory is in effect through Tuesday night for the the coastal waters from Stonington to Eastport out to 25 NM. A Gale Watch is in effect Tuesday afternoon through Tuesday night for the open water 25 NM to 60 NM offshore.

Small Craft Advisory winds and seas are expected to continue over the outer waters through Wednesday night. Seas fall below advisory levels on Thursday. SCA conditions are possible again Friday into Saturday. Conditions are expected to decrease below gales over the offshore waters from 25 to 60nm Wednesday and remain below gales, although there is a chance (30 percent) of a brief gale Wednesday night as winds aloft increase for a few to several hours. Rain Wednesday night and patchy fog is expected to reduce visibility at times. An isolated thunderstorm is also possible.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ050-051. Gale Warning from 4 PM Tuesday to 3 AM EDT Wednesday for ANZ080-081.