Possible Severe Weather Outbreak Update Two

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FXUS61 KCAR 280143

AFDCAR

Area Forecast Discussion

National Weather Service Caribou ME

943 PM EDT Thu Jul 27 2023

.SYNOPSIS...

Low pressure will continue to move east of the region overnight.

A cold front will cross the region Friday night, then exit

across the Gulf of Maine Saturday while low pressure moves along

the front. High pressure will build toward the region Sunday.

Another cold front could cross the region Monday into Tuesday.

&&

.NEAR TERM /THROUGH FRIDAY/...

Update...

Rain that affected portions of the Upper Penobscot Valley and

Downeast Maine earlier this evening has exited into New

Brunswick province. Partial clearing is expected overnight.

Patchy fog is also expected, especially across areas that

experienced rainfall earlier this evening. Lows overnight will

generally range from the low to mid 60s.

previous discussion

By Friday, brief high pressure will move in, pushing in a warm,

moist airmass. Guidance shows a slight decrease in dewpoints

from the previous runs. This with the breezy W-SW winds, heat

indices touch 90F for a short period of time before decreasing

through the evening, thus staying out of criteria for an

advisory for the day.

By the afternoon, a strong cold front approaches from the west.

Some high-res models show the development of the low across the

Crown of Maine, while others push the center of the low to the

north. As the front progresses, a pre-frontal boundary will move

into the northwest, then quickly move SE throughout the

afternoon and into the evening. Models are gaining consistency

with the 12Z run, giving more confidence to strong thunderstorms

within this boundary. Though the CAPE values are maxed out

around 1500 J/kg, the 0-1km and 0-3km shear is above 40kts,

higher K index, and moderate mid and low level lapse rates.

Gusty winds in the upper levels gives higher confidence in

enhanced wording in the areas of thunderstorm risk. It is noted

that these shear values could produce stronger updrafts to

create large hail, but the high freezing layer with a large warm

cloud layer will cause larger stones to melt.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...

A cold front will cross the region Friday night, approaching the

Downeast coast late. Expect a line of showers/thunderstorms across

northern Maine early Friday night in advance of the cold front. Some

of the storms could still be strong early Friday night with

gusty winds. The line will then weaken while crossing central

and Downeast portions of the region. The front will begin to

exit across the Gulf of Maine Saturday. However, an area of low

pressure moving along the front will slow the frontal movement.

The low will bring rain to central/Downeast portions of the

forecast area Saturday. Rain chances will diminish across

northern areas, with likely only partly sunny/mostly cloudy

skies expected across northern Aroostook county. The low will

exit across the Maritimes Saturday night, drawing the cold front

south of the Gulf of Maine. Rain will end Downeast early

Saturday night. Otherwise, expect decreasing clouds across the

region Saturday night. Surface high pressure builds Sunday,

while aloft a possible disturbance crosses the region. Generally

expect partly sunny skies Sunday, though could have the slight

chance of an afternoon shower with the upper disturbance.

Slightly below normal level temperatures are expected

Saturday/Sunday.......

Hazardous Weather Outlook...UPDATED

National Weather Service Caribou ME

733 PM EDT Thu Jul 27 2023

MEZ001>006-010-282345-

Northwest Aroostook-Northeast Aroostook-Northern Somerset-

Northern Piscataquis-Northern Penobscot-Southeast Aroostook-

Central Piscataquis-

733 PM EDT Thu Jul 27 2023

This Hazardous Weather Outlook is for Central Highlands Maine, Far

Eastern Maine, Far Northern Maine and North Woods Maine.

.DAY ONE...Tonight.

Hazardous weather is not expected at this time.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

A cold front could produce strong thunderstorms Friday afternoon

into Friday evening. The main threat would be gusty winds with any

storms.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather

conditions according to Standard Operating Procedures.

$$