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Area Forecast Discussion (AFD)

Issued by Caribou, ME (CAR)

                            
000
FXUS61 KCAR 231620
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
1220 PM EDT Tue Apr 23 2019

.SYNOPSIS...
Low pressure will track across Gulf of Maine today and move 
across Nova Scotia tonight. Another low from the Great Lakes
region will approach late tonight and move east across the 
region Wednesday. Weak high pressure will cross the region on 
Thursday.
&&

.NEAR TERM /THROUGH TONIGHT/...
1145 AM Update: Increased pops and QPF for rainfall near upper
low center in Hancock County and southern Penobscot County.
Also increased afternoon pops towards eastern border as energy
rotates into the state from New Brunswick. Overall QPF amounts
not too much different. The cloudiness will persist through
tomorrow as the inversion won't break until later tomorrow on
the backside of tomorrow's low pressure system.

Orgnl Disc: Latest radar ref trends shows a band of rn from 
remnant sfc and upper low pres ovr the Gulf of ME movg toward NS
prov, with the band slowly movg N from Downeast into Cntrl ptns
of the FA. Models show the max pivot point as far N as NE ME by
mid morn before the band moves E into NB by midday, leaving 
isold to sct shwrs and patchy dz. for the aftn hrs. The combo of
clds, rn/shwrs/dz and NE winds will result in much lower fcst 
aftn hi temps.

After a brief break in precip this eve, models cont to show 
another sfc low from S Cntrl Can/upper great lks apchg the Rgn 
late tngt, with more in the way of rnfl entering our FA from
the west late tngt. There may be enough llvl cold air for a
rain/sleet mix by daybreak Wed ovr far Nrn ptns of the Rgn. In
any event, models have been trending slightly less with QPF 
with this system ovr the last 24 hrs.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Low pres apchg from the Great Lakes will bring a round of
measurable precip to the region as a secondary low develops
along the Maine coast. Precipitation will be in the form of rain
on Wednesday for the most part, but a mix of snow and sleet is
expected during the morning hours across the n and w as colder
resides in the low lying areas. As the low moves to the ne,
colder air looks like it gets pulled back into the region later
Wednesday afternoon w/the threat for the rain possibly mixing
w/some snow across the far n and w. As the low exits through the
Maritimes Wednesday night, there a chance for a changeover to a
brief period of the snow on the backside of the system as the
colder air continues to drain into the region. Temps Wednesday 
night are expected to be in the lower 30s across the northern 
1/2 of the CWA leading to the potential for a changeover to 
snow.The 00z ECMWF/GFS and Canadian Global hint as this 
scenario. Attm, decided to show the transition, but kept it to 
the far n(Crown) and to the w. Confidence is not high in regards
to accumulation. Therefore, only carried trace amounts attm. If
this trend continues, then the daycrew may need to include some
minor accumulation. QPF for this event looks to be on the order
of 0.20-0.35". Not expecting this precipitation to raise rivers
levels significantly than where they are attm. More on this in 
the hydrology section below. 

Precip looks like it ends late Wednesday night w/nne winds
picking up a bit w/mostly cloudy skies across the north staying 
mostly and Downeast seeing partial clearing. High pres is
forecast to ridge across the region during the day on Thursday
right into Thursday night. Winds becoming light will allow to a
possible llvl inversion which will help to keep moisture
trapped. Therefore, more clouds expected on Thursday right into
Thursday night. Temps will be averaging below normal.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
High pressure will exit to the east later Thursday night into
Friday. An upper low w/an intensifying surface low will start
lifting across the region on Friday right into Saturday. This
system is forecast to bring rain during the day on Friday
continuing right into Saturday. There does appear to be a cold
pocket aloft in conjunction w/the upper low. This cold pocket 
of air could possibly allow rain to mix with snow across the far
north and mountains Friday night. The Canadian Global is by far
the most aggressive w/this cold pocket. The ECMWF and GFS are 
not as aggressive and are much warmer in the llvls. Attm, stayed
w/rain across the region w/just a small area of snow/rain mix 
back in the far nw areas near the border. 

The rain is forecast to taper off to showers Saturday evening,
but confidence is low in regards to how quickly this transition
will occur. Uncertainty exists for the potential for another
storm system to affect the region later w/rain or shower.
Temperatures are projected be slightly below normal right into
the weekend.

&&

.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
NEAR TERM: IFR conditions in rn ovr Downeast sites should
improve to MVFR by midday and cont into aftn in isold to sct
shwrs and patchy dz. Nrn TAF sites will be low VFR or MVFR in rn
this morn and MVFR in sct shwrs/dz this aftn. All sites should
be MVFR mainly with clgs and patchy dz this eve and ovrngt then
lower to IFR very late tngt in steady rn.

SHORT TERM: MVFR to LIFR conditions are expected through 
Wednesday across all terminals. VFR/MVFR conditions expected
Wednesday night for KBGR-KBHB/KHUL-KFVE respectively. MVFR
conditions look like they could hold on across the northern
terminals into Thursday w/an inversion setting up. VFR for
KBGR-KBHB. Improvement to VFR later Thursday into Thursday 
evening. MVFR conditions could begin to develop later Thursday 
night for all terminals w/IFR and possibly LIFR Friday.

&&

.MARINE...
NEAR TERM: Will cont with SCA conditions for our outer waters
thru early aftn, with winds and wvs subsiding late this aftn
into tngt. Kept close with WW3/NWPS blended guidance for fcst wv
hts thru the near term.

SHORT TERM: Conditions look like they will below SCA levels
Wednesday and holding as it looks attm right into Thursday.
Winds could gust into the lower 20s Wednesday night as n winds
kick in on the backside of the departing lo. Seas will be
dropping back w/the offshore wind. The next chance for SCA
conditions look to be possible Friday into Saturday w/the apch
of a low pres system from the s. Winds could reach sustained 25
kts w/gusts close to 30 kt. Seas by Friday night could reach 6-7
ft as the latest wave guidance indicates.

&&

.HYDROLOGY...
River Flood Warning for MATM1 and points north, remain in place
until further notice. All the rivers are ice free w/the
exception of Big Black and back at teh headwaters of the St.
John. The continued snowmelt will lead to further increases on 
the St. John and Fish River. Ice looks like it is being flushed
out of the Big Black River per the latest trend of the
hydrograph showing a drop in the stage. 

Areal Flood Advisories continue in effect for Eastern Aroostook
County with some road closures, with non-gauged area 
rivers/streams around bankfull; and for below the Grand Lake 
Matagamon Dam on the E branch of the Penobscot River down to 
Grindstone, where very high levels on Lake Matagamon is just 
below full capacity for the dam. There have been reports of 
road closures along route 11 in/near Grindstone.

Will continue to keep a close eye on the Fish River Chain of Lakes 
through the next week or two, as water levels are beginning to rise 
and this area typically peaks late. Concerned about potential for 
flooding possibly similar to last spring in this area.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...Small Craft Advisory until 2 PM EDT this afternoon for ANZ050-
     051.

&&

$$

Near Term...VJN
Short Term...Hewitt
Long Term...Hewitt/Norcross
Aviation...VJN/Hewitt
Marine...VJN/Hewitt
Hydrology...