textproduct: Caribou

WHAT HAS CHANGED

630 pm update...Update for 00z aviation discussion

- Increased rain chances in the north and south tonight-Tuesday night. - Increased rain totals in Northern Maine for Wednesday. - Confidence continues to increase for significant rainfall at some point from Thursday night into Sunday.

KEY MESSAGES

1) Rain from late today through Wednesday morning. Some drought relief is possible across Northern Maine.

2) Potential for significant rain at some point from Thursday night into early next week, but confidence is still fairly low in timing and amounts. However, confidence is increasing in some drought relief during this time frame.

DISCUSSION

KEY MESSAGE 1... Rain from late today through Wednesday morning. Some drought relief is possible across Northern Maine.

KEY MESSAGE 1 DESCRIPTION... A backdoor cold front ahead of the approaching warm front will bring the initial rain showers tonight and into Tuesday. The NE flow begins late tonight as the warm front pushes in moisture. By Tuesday, the NE flow will become more variable once the warm front moves in. Rain amounts range from 0.75 inches to close to 1 inch in the St John Valley, around a half inch in Aroostook and North Woods, and less than a half inch through the Central Highlands. Further south can expect less amounts with more intermittent rain.

On Wednesday: A northern stream shortwave passes to the north over the top of deep layered ridging building over New England. At the surface and low levels, a warm front lifts northeast across Maine. The result should be steady rain mainly across the North Wednesday morning, possibly lingering into the afternoon across far NE Aroostook County. The main forecast challenge for Wednesday is how quickly the warm front lifts to the northeast. The NBM remains on the warm side across the North, noting its qpf and sky cover - so have under cut it for highs here, but across Downeast Maine and the Bangor region, raised highs a bit to reflect a morning passage of the warm front there. Also used RFC QPF to reflect slightly higher QPF across the north.

KEY MESSAGE 2... Potential for significant rain at some point from Thursday night into early next week, but confidence is still fairly low in timing and amounts. However, confidence is increasing in some drought relief during this time frame.

KEY MESSAGE 2 DESCRIPTION... At least three closed lows are going to influence the regions weather from Thursday night into early next week. Unfortunately, closed lows are among the things that models handle least well, so there is above normal uncertainty in the details during this time frame, in particular the exact timing, strength and location of these systems. However, there is sufficient commonality in deterministic and ensemble solutions, that there is increasing confidence in a significant rainfall at some point from Thursday night into early next week.

In general the first closed upper low passes to the north Thursday night and Friday, The second closed low slowly tracks from the Great Lakes to southern Quebec Friday night through Saturday night, then passes near or to the north of the region Sunday and Sunday night. The third closed low then approaches from the west on Monday. What is the most uncertain is how much interaction these three systems have with each other. In general the more interaction, the more rainfall, the less interaction, then lower amounts of rainfall. For now the chance for at least 1" of rain in this time frame ranges from 45% across far NW Maine to around 75% in coastal Washington County. The chance for at least 3" of rain in this time frame ranges from around 10% across N Penobscot/SE Aroostook to around 40% along the Downeast Coast. Based on the increasing probabilities, there is increasing confidence in some drought relief from rainfall late this week/early next week.

At this time, the most significant winds from Thursday night into early next week are expected offshore, with wind gusts over land, outside of higher elevations, likely 35 mph or less.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

Tonight...MVFR cigs at Aroostook terminals developing later this evening. May see a brief period of VFR cigs at CAR and PQI as northeast winds allow low deck to scatter out. W winds 5-10kts becoming light and vrb after midnight.

Tuesday-Tue night: MVFR or lower likely at all terminals Tuesday, becoming mainly IFR Tuesday night. LLWS possible Tuesday night. Light winds.

Wednesday: MVFR or lower likely at northern terminals. MVFR or lower becoming VFR at southern terminals. LLWS possible Wednesday morning. W-WNW winds G15-25KT possible Wednesday afternoon.

Wednesday night-Thursday: VFR.

Thursday night-Saturday: MVFR or lower possible. LLWS possible Friday-Saturday.

MARINE

The WSW winds will decrease tonight, becoming light and variable on Tuesday. Expect SE winds 5-10 kts on all waters Tuesday night. Winds and seas below SCA levels for this period.

From Wednesday through Friday, sustained winds should be 15kt or less and seas 4 ft or less over all waters. SCA conditions are possible over the coastal waters and gales possible over the outer waters Friday night and Saturday, with seas possibly building to 5 ft on the intra coastal waters, 8-10 ft on the coastal ocean waters and 10-16ft on the outer waters Saturday, if the stronger winds are realized. Confidence in the higher values of winds and seas remains fairly low at this time (generally 25-45% for winds and 15-30% for seas).

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...None.