textproduct: Caribou

WHAT HAS CHANGED

- Lowered dew points for Monday late morning until sunset.

- Capped pops for Tuesday at likely, and upped QPF.

- Lowered pops for Wednesday.

KEY MESSAGES

1) Mild, mainly dry and breezy conditions into Monday may lead to some fire weather concerns.

2) Warm to very warm Tuesday and Wednesday, with strong to possibly severe thunderstorms possible Tuesday afternoon/early evening as well.

3) Soaking rainfall possible Saturday night and Sunday.

DISCUSSION

KEY MESSAGE 1...Mild, mainly dry and breezy conditions into Monday may lead to some fire weather concerns.

KEY MESSAGE 1 DESCRIPTION... A brief period of frost may develop tonight across the North Woods into portions of Eastern Aroostook County. On Monday, dry conditions will remain prevalent, with very dry mid levels Monday morning and steep lapse rates to begin the day. A lifting warm front will begin to increase cloud cover from south to north through the day. So though conditions remain similar to the previous day with dry weather and rapidly dropping dewpoints, the decrease in dewpoints and humidity will stall through the afternoon as more moisture returns to the atmospheric profile. Even still, relative humidity will easily fall into the 24-30 percent range through the first half of the day, though with a relaxed pressure gradient aloft, winds will be relatively light through the day as well. In the afternoon as winds shift SW and began increasing 5-15mph with gusts up to 20mph late day especially in the Bangor Region and Downeast. Will need to monitor fire weather concerns given the recent dry conditions, green up is underway and accelerating but still fine fuels available.

KEY MESSAGE 2... Warm to very warm Tuesday and Wednesday, with strong to possibly severe thunderstorms possible Tuesday afternoon/early evening as well.

KEY MESSAGE 2 DESCRIPTION... Deep layered ridging crests over the area Tuesday, with its axis exiting to the east on Tuesday night. This puts the region in SW flow aloft for Wednesday, with a northern stream shortwave trough approaching from southern Canada.

The high resolution models are latching onto a meso-convective vortex forming from convection over the Central Plains today, tracking ene into the Great Lakes by Monday evening, then tracking across far southern Ontario and Quebec Monday night into Tuesday morning, before crossing Maine late Tuesday morning through Tuesday afternoon. This shortwave energy working its way over the top off the ridge should spawn numerous showers and isolated to scattered thunderstorms across Northern and Central Maine from late Tuesday morning into early Tuesday evening, with more scattered convection further south into the Bangor Region and interior Downeast Maine. With 750-1750 J/kg of CAPE, 25-35KT of bulk shear, along with Downdraft CAPE in areas of 700-1100 J/kg, have the potential for strong to possibly locally severe thunderstorms from late Tuesday morning into early early Tuesday evening. The main threat is from strong gusty winds, along with a chance for some large hail. In addition with 0-3km storm- relative helicity values ranging from 100-300 m2/s2 and peak Energy Helicity Index values of 1-1.5, an isolated EF0/EF1 tornado cannot be completely ruled out. The best chance for any severe storms will be from the Central Highlands on east- southeast into Southern Aroostook and interior Downeast Maine.

Locally heavy rainfall is possible as well on Tuesday, with models still showing the potential for 1-1.5" of rain in a 3 hour period. The best chance for this is across the same area with the best severe threat. Areas experiencing locally heavy rainfall will see the ponding of water on roadways with resultant hydroplaning of vehicles who do not reduce speed.

Highs on Tuesday should be warm to very warm, some 10-20 degrees above normal, with the largest departures across the Bangor Region and interior Downeast Maine. With dewpoints int he afternoon from around 60 to the mid 60s, the heat index should reach the mid 80s across Central and Southern Penobscot, Southern Piscataquis counties and interior Downeast Maine,with lessor values elsewhere.

The models are backing away from the convective threat on Wednesday, as subsidence under the exiting deep layered ridge could severe as a cap. The high resolution models suggesting the cold front cold pass by dry, while the global models still want to kickoff some showers and thunderstorms ahead of it. NBM pops were at most chance, with only a slight chance of thunder.

It should be noted that the ingredients for strong to locally severe storms are still fairly similar to those seen on Tuesday, so if any storms do form, they could be strong to locally severe as well, with the main threat being strong gusty winds and small hail. The main difference is that 0-3km helicity values peak out at 200 m2/s2, with EHI peaking out around 1, so there is less of a potential for weak tornadoes, however the chance is not 0.

Highs on Wednesday should be lower than on Tuesday across the NW 1/3 of the CWA where the cold front goes through by around midday, but warmer than Tuesday across Central/Southern Penobscot, southern Piscataquis and Downeast Maine. However, it appears dewpoints should be a little lower, so heat indices should be around the same as on Tuesday.

KEY MESSAGE 3... Soaking rainfall possible Saturday night and Sunday.

KEY MESSAGE 3 DESCRIPTION... The axis of a northern stream trough crosses the area late Saturday night and Sunday morning as a coastal low passes to the south. This could bring a widespread soaking rainfall to the region from Saturday night into Sunday.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

Rest of Today...SCT-BKN VFR. W-NW winds 10-15kt gusting 20-35kt. LLWS at BGR has been noted via PIREPs which expected to end this evening.

Tonight...SCT-BKN VFR becoming SKC or high cigs. W-NW winds 5-15kt becoming light and variable late.

Monday...VFR. Light and variable winds becoming S-SSW in the afternoon 5-10kt.

Monday night...VFR. Brief MVFR possible with -SHRA at FVE, CAR and PQI. Cannot rule out VCTS at FVE and CAR. S winds 5-10kt.

Tuesday/Tuesday evening: MVFR or lower possible in any stronger thunderstorm, with the best chance in the afternoon/early evening at KCAR/KPQI/KHUL/KBGR. WSW winds G15-20KT possible Tuesday afternoon. LLWS possible Tuesday evening.

Late Tuesday night-Wednesday morning: VFR. LLWS possible late Tuesday night. SW winds G15-20KT possible.

Wednesday afternoon: MVFR or lower possible in any stronger thunderstorm, with the best chance at southern terminals. W-NW winds G15-25KT possible.

Wednesday night-Friday: VFR. NW winds G15-20KT possible, with the exception of Thursday night.

MARINE

Small Craft Advisory has been extended till 8PM this evening for seas 4-6ft. Winds/seas below SCA tonight into Monday evening. Gusts Monday night may reach 25kt on the waters 25-60nm offshore. Seas 2-4ft on Monday into Monday night. Sea surface water temperatures range 42-46F across the waters from the Downeast coast out 60nm including Penobscot and Passamaquoddy Bays.

SCA conditions are possible on the coastal ocean waters Tuesday, with sub-SCA conditions expected on the intra-coastal waters. SCA conditions are then possible on all coastal waters Tuesday night through Wednesday night. SCA conditions are then forecast on the coastal waters from Thursday through Friday. On the outer waters wind gusts to 30 kt are forecast Tuesday through Wednesday night. Winds should be less than 25 kt and seas 5 ft or less on the outer waters Thursday through Friday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Beach Hazards Statement until 8 PM EDT this evening for MEZ029- 030. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ050- 051.