textproduct: Caribou

WHAT HAS CHANGED

- Increasing confidence for decoupling Tuesday night, which could result in frost in the north.

- Confidence continuing to increase in a soaking rain Wednesday night and in gusty winds Wednesday night and Thursday.

KEY MESSAGES

1) Chilly overnight Tuesday night. Chance for frost in the north.

2) Soaking rain is expected areawide Wednesday night, with gusty winds Wednesday night and Thursday. Can't rule out isolated power outages during the day Thursday from the wind.

DISCUSSION

KEY MESSAGE 1...Chilly overnight Tuesday night. Chance for frost in the north.

KEY MESSAGE 1 DESCRIPTION... Cool airmass moves over northern Maine Tuesday night. There is a chance for atmospheric decoupling early in the night, as skies clear out. This will help temperatures to drop into the 30s. Potential for northern areas in Aroostook to drop into the low- to-mid 30s, which will lead to some frost development. Frost chances are going to be highly dependent on the timing of some high level clouds moving in late Tuesday night into early Wednesday morning. If the clouds move in earlier in the night, temperatures will stabilize faster. If clouds move in slower, then there is more time for the temperatures to drop with clear skies. Currently, the set up looks more favorable for decoupling, and thus colder temperatures.

The next chance of frost comes Friday night.

KEY MESSAGE 2...Soaking rain is expected areawide Wednesday night, with gusty winds Wednesday night and Thursday. Can't rule out isolated power outages during the day Thursday from the wind.

KEY MESSAGE 2 DESCRIPTION... Fairly strong system expected Wednesday night/Thursday. Surface low pressure will be passing well to our north, with a potent warm front Wednesday night followed by a cold front Thursday. A few impressive things about this system include an unusually strong upper level westerly jet stream, high precipitable water, and unusually strong 850mb winds. These three parameters are running above the 95th percentile for this time of year.

Rain: Rain looks to begin early Wednesday evening and taper off around sunrise Thursday. The rain will be occasionally moderate, and can't rule out an embedded thunderstorm with some instability aloft. We are looking at over 0.25 inch rain for most areas, with a 50-75 percent chance of exceeding 0.50 inch. Chances are only 20 percent or less of exceeding 1 inch though. This won't be enough rain for flooding concerns, but will help with the dry conditions/drought. Could be a few showers persisting during the day Thursday mainly in the north, but the vast majority of the rain comes Wednesday night.

Wind: As mentioned before, we are looking at potent winds aloft, most likely coming in the middle of the night Wednesday night from the south, and again during the day Thursday from the west. The winds aloft will be the strongest Wednesday night with up to about 55 kt at 850mb, but it is very unlikely that these winds will reach the ground due to stable low levels that are decoupled from the atmosphere aloft. More realistically, we are looking at gusts as high as about 30 mph from the south Wednesday night. During the day Thursday, though the winds aloft aren't quite as strong, the winds have a much better shot at mixing down to the ground thanks to cold advection aloft with steeper lapse rates, plus the fact that it's daytime. Gusts to about 35 mph from the west appear likely Thursday, and with wet soils after Wednesday night's rain plus leaves on the trees, there could be very isolated tree damage/isolated power outages. It remains breezy Thursday night/Friday, though not quite as much as Thursday.

AVIATION /06Z TUESDAY THROUGH SATURDAY/

Today...VFR at northern terminals. Isolated showers possible central and Downeast areas early morning, moving from north to south. Afterwards, VFR. NW winds 10-15kts with gusts up to 20-25 kts.

Tuesday night-Wednesday...VFR overnight into the morning, becoming MVFR/IFR late Wednesday evening as rain moves in from the west. Light winds Tuesday night, becoming S winds 5-15 kts on Wednesday, with gusts 20-25 kts possible.

Wednesday Night...MVFR/IFR with rain. S wind around 15 kts with gusts to 25 kts, and likely LLWS with much strong winds aloft.

Thursday...Mainly VFR, with a chance of MVFR north in the morning. Windy with W winds 15-20 kts with gusts to 30 kts.

Thursday Night and Friday...VFR with W winds 10-20 kts, gusting 25-30 kts during the day Friday.

Friday Night and Saturday...VFR with light winds.

MARINE

Conditions below Small Craft Advisory levels today through Wednesday. Seas generally 2-4 ft. Isolated showers possible early this morning. W winds this morning, shifting NW this afternoon. Winds shift NE Tuesday night, and become S on Wednesday.

S/SW winds peak late Wednesday night, with about a 40 percent chance of gales within 25 NM of the coast, and a 60 percent chance of gales beyond 25 NM. Winds ease back below 25 kt by late Thursday. Seas peak in the range of 5-9 ft late Wednesday night into Thursday morning and then gradually subside. Winds gradually shift to the NW for Friday and become variable and light Saturday.

CAR WATCHES/WARNINGS/ADVISORIES

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