Wednesday, November 15, 2023

Mid-November Subtropical Storm

























000
FXUS61 KCAR 160133
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
833 PM EST Wed Nov 15 2023

.SYNOPSIS...
A weak cold front crosses the area overnight. High pressure
will build across the region Thursday. A warm front approaches
from the southwest Thursday night, then lifts to the northeast
on Friday. A cold front crosses the area Friday night and
Saturday morning as an area of low pressure tracks well offshore
through Saturday. This low then tracks into the Canadian
Maritimes Saturday night, followed by a trough of low pressure
crossing the area on Sunday. High pressure then builds in from
the west Sunday night and Monday.

&&

.NEAR TERM /THROUGH THURSDAY/...
830 PM Update: Based on latest radar ref trends, we did increase
snow shwr cvrg a little to sct across far Nrn areas for the
remainder of the Eve. From the standpoint of QPF/snfl, it
matters little with any accumulation of snfl related to far Nrn
higher trrn lctns. With cld cvr and llvl warm advcn ahead of
the cold front going into the Ovrngt hrs, temps should be steady
to slowly rising during this tm frame with no chgs to fcst
ovrngt lows attm.

Prev Disc: In a fast zonal flow, surface and upper level
ridging move eastward offshore this evening. Warm advection and
a subsidence inversion is causing stratocumulus clouds in
northern Aroostook County that will finally dissolve by this
evening. A weakening northern stream shortwave with minimal
moisture crosses the area later tonight with a weak surface cold
front. There is very little lift with this feature...maybe just
enough to graze the Saint John Valley with a few snow showers
late evening. QPF of a hundredth of an inch or so is as much as
we can reasonably anticipate. Further south, no QPF is forecast.

Cloud cover and warm advection will limit low temperatures to
the lower 30s tonight. There is nominal cold air advection
behind the cold front as measured at 850 and 925mb, but sunshine
and deeper mixing are expected to generate warmer temperatures
on Thursday. Mid 40s are expected towards Presque Isle while
readings near 50F are forecast for Bangor, Brewer and eastward
towards Ellsworth and Machias. While always vary of persistent
thin stratocu fields, strong surface/upper ridging and PWs
dropping below a quarter inch helped influence the decision to
go with sunny skies on Thursday.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
Northern stream ridging crosses the area Thursday night then
exits to the east on Friday. A combination of subsidence under
the ridge, followed by negative vorticity advection in SW flow
on its backside will keep things dry Thursday night and Friday
morning and quite likely through most if not all of Friday
afternoon. Thursday night and Friday morning should see minimal
cloud cover, then there should be increasing mainly high and
mid clouds Friday afternoon from SW to NE. Some isolated to
possibly scattered showers are possibly across mainly far NW
zones late Friday afternoon ahead of the next system.

Lows Thursday night should be near normal and highs on Friday
10-15 degrees above normal.

A full latitude trough develops over the eastern US Friday
night. The models differ over its exact timing and orientation,
the placement and strength of shortwaves embedded in its flow,
and the extent to which it interacts with a southern stream
system located off the east coast of Florida. What they do agree
on is precipitation should start a little later than previously
forecast, with a steady rain developing, except possibly mixed
with snow over the higher elevations over far NW Aroostook. It
could be quite breezy Friday night, with gusts of 25-35 mph
possible. Lows Friday night should be around 15 degrees above
normal.

The models then split into roughly two camps for Saturday, with
high resolution models and the CMC-Global and some ensemble
members with a more progressive, positively tilted trough,
allowing for the associated surface cold front exits offshore
by Saturday evening, with the coastal low being farther to the
east as a result. This would bring precipitation to the end over
most areas Saturday morning. The other camp has the GFS, ECMWF
and a majority of the ensemble members, with a slower more
neutral tilted trough. As a result the surface cold front makes
slower progress through the state and the coastal low comes
closer towards SW Nova Scotia. This allows for overrunning flow
to set up on the cold side of the front, and rain through
afternoon, mixing with or changing to snow across the north.
Both camps solutions are plausible, so for now went with a
blended approach - lingering precipitation, especially across
the north through the afternoon, but with only chance vice
likely pops. Highs on Saturday will be in the morning across
most areas, except for across Downeast Maine where an afternoon
high is possible. Temperatures on Saturday should be around 10
degrees above normal.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
All models agree that the axis of the full latitude trough
pushes through Saturday night. Models do agree that
precipitation will end sooner than previously forecast,
including the GFS/ECMWF camp, so taper off precip after
midnight. If the GFS/ECMWF camp is right there is the potential
for a flash freeze Saturday evening along with a period of
accumulating snow across the north before the precipitation
tapers. If the CMC- Global camp is correct, Saturday night
should be dry, with NW winds likely drying most road surfaces
before a flash freeze can occur. Given this spread in solutions,
do not have the confidence to mention anything in the HWO at
this time.

A northern stream trough axis crosses the area on Sunday, with
some flurries possible (though not quite confident enough to
reflect this in the forecast).

Deep layered ridging builds in Sunday night through Monday
night, then slides to the east Tuesday. It should be dry from
Sunday night into Tuesday as a result, and possibly all day
Tuesday depending on how quickly the ridge axis actually slides
to the east. For now, have slight chance pops over far W and S
portions of the region for late day showers.

Another full latitude trough approaches Tuesday night and
Wednesday. This warrants increasing pops to chance for a period
of overrunning precipitation. This should be mainly snow across
the North Tuesday night, mixing with or changing to rain on
Wednesday with mainly rain elsewhere.

Temperatures should be near normal Saturday night, then below
normal Sunday-Monday night. Temperatures should be above normal
Tuesday-Wednesday.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
NEAR TERM: MVFR cigs remain north of HUL this afternoon. These
clouds will move out later this afternoon, but MVFR cigs return
again tonight as a warm front lifts north this
evening...followed by a cold front late tonight. A brief snow
shower late this evening could produce IFR vis at FVE, but not
concerned about reductions in vis elsewhere. There is also a
small chance of IFR cigs at HUL tonight with the warm front, but
confidence is insufficient to include in TAF.

For BGR and BHB, the predominant condition tonight will be VFR.
There is a small risk of MVFR cigs this evening as clouds in
the Gulf of Maine lift northward for a brief period.

For Thursday, went with VFR at all sites except FVE where MVFR
remains. It is possible that thin stratocumulus could still
generate MVFR cigs for HUL/PQI/CAR too, but opted to bet on
scattered skies or at least cigs above 3000 ft.

SHORT TERM:
Thursday night-Friday...VFR, with exception of MVFR possible
over far NW Maine late Friday. LLWS possible.

Friday night-Saturday...IFR or lower developing Friday night.
Conditions could improve to VFR from NW to SE on Saturday. LLWS
possible Friday night. N-NW winds G15-25KT possible Saturday.

Saturday night...A chance of MVFR or lower in the evening, with
rain changing to snow, otherwise VFR. NW winds G15-25KT
possible.

Sunday-Monday...VFR. NW winds G15-20KT possible Monday.

&&

.MARINE...
NEAR TERM: 830 PM Update...Southwest winds will pick up this
evening with gusts over 25 kt based on expected mixing. As a
result, the current Small Craft Advisory til 5am EST has been
extended in areal coverage to include the inner bay/harbor
waters. The winds will cont into the late night hours then
diminish by daybreak, becoming west to northwesterly at 10 to 20
kt.

SHORT TERM: Sub-SCA conditions are expected on all waters
Thursday night and Friday morning. SCA conditions develop on
all waters Friday afternoon. Gales are possible on the coastal
ocean waters Friday night-Saturday night, this threat will be
highlighted in the HWO. Conditions should be just below SCA levels
on the intra-coastal waters during this time frame, with a very
low chance of gale gusts (to low to reflect in the HWO). SCA
conditions are forecast on all waters on Sunday, with these
possibly lingering into Monday on the coastal ocean waters.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...Small Craft Advisory until 5 AM EST Thursday for ANZ050>052.

&&

$$

Near Term...VJN
Short Term...Maloit
Long Term...Maloit
Aviation...VJN/Maloit
Marine...VJN/Maloit


ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
700 PM EST Wed Nov 15 2023

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Southwestern Caribbean Sea (AL98):
A broad area of low pressure over the southwestern Caribbean Sea is 
producing a large area of disorganized showers and thunderstorms.
Environmental conditions appear marginally conducive for 
development of this system over the next couple of days, and a 
tropical depression could form by this weekend as the system  
moves northeastward across the western and central part of the 
Caribbean Sea.  An Air Force Reserve reconnaissance aircraft is 
scheduled to investigate the system tomorrow. 

1. Regardless of development, this system is expected to produce heavy 
rains that could result in flash flooding and mudslides over 
portions of the Caribbean coast of Central America and the Greater 
Antilles through this weekend. Interests in Jamaica, Cuba, Haiti, 
the Dominican Republic, the southeastern Bahamas, and the Turks and 
Caicos Islands should continue to monitor the progress of this 
system. 
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 7 days...medium...50 percent.

2. Offshore Southeast Coast of United States:
A non-tropical area of low pressure appears to be forming near 
southern Florida along a frontal boundary.  This system is forecast 
to move quickly northeastward across the Bahamas and offshore of the 
east coast of the U.S. through the weekend.  Although development 
into a tropical cyclone appears unlikely, this system is expected to 
produce gusty winds and heavy rains across portions of southern 
Florida, the Florida Keys, and the Bahamas during the next couple of 
days.  For more information on this system, including gale warnings, 
see High Seas Forecasts issued by the National Weather Service.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 7 days...low...10 percent.

High Seas Forecasts issued by the National Weather Service
can be found under AWIPS header NFDHSFAT1, WMO header FZNT01 
KWBC, and online at ocean.weather.gov/shtml/NFDHSFAT1.php

Forecaster Cangialosi

0 Comments:

Post a Comment

<< Home