Potentially Historic June Heatwave On The Way Update One

389

FXUS61 KCAR 061531

AFDCAR

Area Forecast Discussion

National Weather Service Caribou ME

1131 AM EDT Sun Jun 6 2021

.SYNOPSIS...

A front will stall across interior Downeast Maine today. High

pressure will build south of the area Monday. Another cold front

will cross the area Tuesday. High pressure will build in from

the northwest Wednesday into Thursday......

......SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...

A real toasty of a day expected for Monday w/record temps possible.

The latest NAM/GFS and ECMWF show a trof at the sfc and aloft,

moving across the region during the early part of the day.

Interestingly enough, the GFS wants to bring some light showers

across western and northern areas Monday morning w/the trof. The

latest run of the HRRR does hint as some weak reflectivity

across the north and even across the Penobscot region during the

morning, but this is the earlier runs were dry. The NAMNEST did

show spotty reflectivity, but looking very weak. The

operational 00Z NAM and ECMWF are dry. Therefore, decided to

keep it dry w/the westerly flow aloft and very weak forcing. S

winds will become SW and increase to 10-15 mph w/some higher

gusts. This will bring some hot temperatures to the region by

the afternoon on the leading edge of high pres to the sw. 925MB

temps are progged to reach 25-26C leading to temps in the blyr

to reach into the low/mid 90s, especially inland areas. The SW

wind will bring cooler air in from the Gulf of Maine to cool

coastal sites some. Heat indices to get close to Heat Advisory

criteria w/a few inland sites forecast to reach 94-95F for a

couple of hrs. Dewpoints climbing to 60-65F will make it for a

humid day as well. The daycrew can assess this further today to

see if a headline will be needed. A warm night expected Monday

night and continued humid w/overnight temps in the 60s to around

70.

For Tuesday, a pre-frontal trof moving is expected to move into

the region during the day w/showers and the threat for some

tstms firing up by the afternoon. There is good CAPE forecast to

set up across the region, especially across the Downeast region

w/1000+ joules and modest lapse rates to support tstms. There

is shear forecast to be around 25 kt. The lacking feature is the

depth of available moisture for organized cells. Attm, per

collaboration w/GYX, decided to go w/isold tstms. It will be

another hot day w/temps forecast to be in the upper 80s to lower

90s. The sfc cold front is forecast to slide out of Quebec and

move across the region Tuesday night w/some scattered showers

and perhaps a tstm in the evening. Some cooling behind the front

w/overnight temps dropping back into the 50s. Refreshing from

the last few nights of humid wx.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...

The cold front is forecast to stall across the Downeast region

on Wednesday w/the threat for more showers and tstms. There is

some warming in the llvls w/some available sunshine during the

afternoon which will aid in destabilizing the atmosphere and

allowing for possible convection. The main activity will be

across the central and downeast areas. Much colder air set to

arrive into the region Wednesday night w/the GFS touting 925mb

temps to drop down to 3 to 4C across the northern and western

areas by early Thursday morning. This is quite a change from the

last few days. Nw winds are forecast to stay up around 10 mph,

which will help negate any frost potential. High pres is

expected to slide across the region on Thursday w/a much cooler

day as daytime temps in the upper 60s to lower 70s across the

north and west. Central and downeast areas are expected to see

mid 70s. Thursday night could be a chilly night as high pres

slides across the areas and winds drop off. Clear skies and a

good shot for radiational cooling could very well lead to temps

in the valleys to drop into the 30s w/frost a possibility. This

will all depend on the orientation of the high as the latest GFS

does show light SSE winds setting up late Thursday night, which

could offset any frost. We will have to see how this plays out

as we move through the week. Friday looks to be a rather dry day

w/a weak disturbance moving through the region and possibly

kicking off a few light rain showers, but nothing significant.

Shower chances could increase by Saturday as another disturbance

moves through the region in the upper NW flow........