Late August Summer Storm

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FXUS61 KCAR 260117

AFDCAR

Area Forecast Discussion

National Weather Service Caribou ME

917 PM EDT Thu Aug 25 2022

.SYNOPSIS...

A wave of low pressure develops along a stalled out front

over upstate New York tonight, then tracks across southern

Maine from Friday into Friday evening. High pressure builds in

through Saturday night, then slowly slides offshore through

Monday night. A frontal system approaches on Tuesday

.NEAR TERM /THROUGH FRIDAY/...

9:15 PM Update...Latest shortwave satellite imagery shows lots

of low cloudiness across southern sections so increased cloud

cover Downeast through late evening. Temperatures have dropped

to around 60 north under a mostly clear sky but are still in the

low 70s across southern Penobscot and Downeast so raised temps

south through mid evening. Lowered temps a bit over the north.

Models cont to be in reasonable good agreement with the

sequence of events with the next upcoming wx event, with

exact placement of heavier rnfl QPF still in question spcly

Fri aftn.

For Tngt, models indicate that a stationary front will remain

near the Downeast coast with dmnshg Eve shwrs and oceanic St

and fog likely making a come back ovr Downeast areas ovrngt,

spcly late tngt. In the meantime, high and mid cldnss will begin

to spread ovr Nrn/Cntrl ptns of the FA late this eve thru the

ovrngt ahead of a zonal s/wv and weak sfc low pres from Cntrl

Can with isold to sct shwrs advcg into these ptns of the Rgn

very late tngt.

Fri will see more organized rnfl spreading ovr spcly Nrn/Cntrl

ptns of the FA by midday as the upper s/wv trof apchs the St

Lawrence vly of QB. The consensus weak sfc low pres appears to

track across Cntrl ptns of the FA Fri Aftn into Eve into S Cntrl

NB Prov. This implies that there will be a lmtd warm frontal

passage nwrd of the stationary front to perhaps as far N as

Greenville to just S of Houlton by Midday to Erly Aftn. N of the

front at that tm rnfl will be msly stratiform with low top MBEs

and a slgt chc of tstms. S of the front ovr Cntrl and Downeast

ptns of the FA Fri Aftn into Erly Eve, there will be a better

chc of higher cnvctn, but given the lmtd ability of getting much

sfc htg and sig llvl lapse rates for strong winds appears lmtd

attm for these areas, but tstms ovr this ptn of the FA may have

heavier rnfl rates.

If cnvctn SW of our FA into SW ptns of the FA is stronger Fri

aftn, that may somewhat reduce the amt of moisture transport

for heavier rnfl for the N hlf of the FA N of the warm front.

For now, we went with about 65 percent toward WPC`s aftn fcst

update of 6 hrly QPF in the Fri 12-18z and 18-24z tm frames with

some up and down QPFs noted for these tm pds in past major fcst

updates. Lastly, we updated the HWO to highlight this event

tomorrow mentioning the possibility of lcly hvy rnfl that may

cause lcl minor flooding, although the probability of any flood

statements needed for Fri Aftn/Eve is thought to be 50 percent

or less attm, with most lctns xpctd to receive event total

rnfl of 0.50 to 1.00 inches, with lcly higher totals possible.

&&

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

A northern stream trough crosses Maine Friday night. There could

be some lingering strong showers, and possibly a rumble of

thunder ahead of it mainly Downeast early Friday evening.

Otherwise, it will be slow for the low levels to dry out, so

could see patches to areas of fog develop. Lows Friday night

should be a few degrees below normal - mainly from around 50 to

the upper 50s.

A northern stream shortwave passes on Saturday, by then low

levels should have dried enough that it should be dry, with

decreasing cloud cover in its wake as well. Highs on Saturday

should be around 5 degrees below normal - mainly from around 70

to the mid 70s.

The region will be under a mean zonal flow Saturday night and

Sunday - with some weak shortwave ridges and troughs embedded in

that flow. Noting the lack of any significant forcing it should

be dry and with not much in the way of cloud cover. Lows

Saturday night should be around 5-10 degrees below normal and

highs on Sunday near normal.....

Hazardous Weather Outlook

National Weather Service Caribou ME

410 PM EDT Thu Aug 25 2022

MEZ001>006-010-011-015>017-029>032-262200-

Northwest Aroostook-Northeast Aroostook-Northern Somerset-

Northern Piscataquis-Northern Penobscot-Southeast Aroostook-

Central Piscataquis-Central Penobscot-Southern Penobscot-

Interior Hancock-Central Washington-Coastal Hancock-

Coastal Washington-Southern Piscataquis-Northern Washington-

410 PM EDT Thu Aug 25 2022

This Hazardous Weather Outlook is for Central Highlands Maine,

Coastal DownEast Maine, Far Eastern Maine, Far Northern Maine,

Interior DownEast Maine, North Woods Maine and Penobscot Valley

Maine.

.DAY ONE...Tonight.

Hazardous weather is not expected at this time.

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

Rain will develop from west to east Friday, becoming locally

heavy at times Friday afternoon, before tapering off Friday evening.

Localized minor flooding of poor drainage areas is possible.

There is also a chance for thunderstorms Friday afternoon and

evening, in addition to locally heavy rainfall. The best chance

for stronger storms with gusty winds will be south of a Dover-

Foxcroft to Danforth line.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather

conditions according to Standard Operating Procedures.

$$

10:20 PM ADT Thursday 25 August 2022

Special weather statement in effect for:

Fredericton and Southern York County

Significant rainfall is possible Friday night.

Total rainfall: 25 to 45 mm. Locally higher amounts possible.

Locations: central and parts of northern New Brunswick.

Time span: Friday afternoon continuing overnight.

Remarks: Rain is expected to begin Friday afternoon and may become heavy, at times, over some areas. Embedded thunderstorms bringing locally gusty winds are likely. The rain will taper off from west to east by Saturday morning.

There remains significant uncertainty with both the timing and strength of this rainfall. As the system approaches from the St Lawrence River valley rainfall warnings or thunderstorm watches may be required.

Dry ground has a reduced ability to absorb heavy downpours. Heavy rain can cause flash floods and water pooling on roads. Localized flooding in low-lying areas is also possible. Rainfall warnings are issued by meteorologists when at least 50 mm of rain is forecast to fall in a 24 hour period. Severe Thunderstorm warnings are issued when a local area is receiving 25mm/h from a thunderstorm.

Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to NBstorm@ec.gc.ca or tweet reports using #NBStorm.