705
FXUS61 KGYX 280028 CCA
AFDGYX

Area Forecast Discussion...CORRECTED
National Weather Service Gray ME
828 PM EDT Mon Jul 27 2026

.WHAT HAS CHANGED...
Updated for 00Z Aviation section. Previous forecast is in good
shape and simply lined up near term forecast with evening
observations. Showers continue to percolate along/north of the
mountains but should wane as we lose solar insolation.

&&

.KEY MESSAGES...
1. Showers and thunderstorms develop across New Hampshire
Tuesday. Some of these may contain lingering heavy downpours
through early evening.

2. Slow moving low pressure crosses the area Wednesday through
Friday with locally heavy rainfall possible. The threat for
Flash Flooding is low.

3. August starts dry, but shower and thunderstorm chances
return early next week.

&&

.DISCUSSION...
KEY MESSAGE 1 DESCRIPTION...

Showers with some thunder will tend to decrease in coverage
across the mountains of Maine and northern New Hampshire this
evening. These have been somewhat slow moving, with low
environmental shear preventing these from sustaining an
updraft. Other than some low stratus or fog development along
the coast and into the interior this evening, tonight should
remain fairly quiet.

Tuesday begins mostly dry as low pressure begins to close off
arriving from the Great Lakes. The same low shear environment
will exist, but additional forcing and moisture will be arriving
across the western portion of the forecast area (New Hampshire
primarily). Hires guidance, including the HREF and REFS, has
continued to show the potential for isolated heavy rainfall
amounts greater than an inch across central and southern NH.
These are likely individual storms that can sustain themselves,
but are moving slow in limited flow magnitude. In a precip
efficient environment (PWAT greater than 1.25 inch, warm cloud
depth approaching 12kft, and mean RH greater than 90 percent)
the WPC`s Marginal risk of excessive rainfall fits well for
isolated instances of flash flooding.

The caveat is this occuring over a portion of the forecast area
that has been very dry and has flash flood guidance values of 2
to 3.5 inch per one hour. If anything, the main concern may be
tracking areas that see decent rainfall Tuesday, ahead of the
more widespread rainfall into the remainder of the week.

Showers/thunder Tuesday should retreat west with the loss of
daytime heating, but can`t rule out a few more showers rotating
in as the primary circulation pivots just to the west in NY.

KEY MESSAGE 2 DESCRIPTION...
Global models are slowly coming into agreement on the evolution
of this weeks system, and one of those aspects is the surface
low track. All camps now depict the center of the surface low,
and for the most part the upper low, passing south of our area
midweek. How exactly this impacts rainfall amounts seems to
remain a point of contention, but one thing that can be said
with confidence is that this will eliminate much of the
influence from the low level jet. The spread in strength of the
moisture transport has decreased with the ECMWF Ensemble, GEFS,
and NAMNest all depicting PWAT values in the ballpark of 1.50 to
1.75 inches south of the mountains during the day Wednesday,
with values 1.25 to 1.50 inches to the north. BUFKIT soundings
also suggest warm cloud depths 10-12kft, so even without
favorable jet dynamics rainfall is going to be efficient. That
being said the difference in PWAT values is still causing some
large spread in the modeled QPF. The Euro ensemble remains on
the high end of the aforementioned range and maintains it`s
moderate to high confidence (50-70% probabilities) of a
widespread 1-2 inch rainfall. Meanwhile, the GEFS is more in the
middle of the PWAT range and maintains its low confidence
(10-30% probabilities) in rainfall exceeding an inch. This
spread remains a forecast challenge, but I think at this point
it is fair to say that Wednesday into Thursday is going to
feature a more stratiform steady rain, and less in the way of
convective features. Regardless, as mentioned earlier rain will
be moderate to heavy at times and may pose an isolated urban and
complex terrain flooding threat. Elsewhere, recent dry
conditions have left soils with high infiltration capacity and
ample subsurface storage, which should absorb the bulk of
initial rainfall. The exception would be locations that see
heavy rainfall on Tuesday and are saturated going into the
stratiform rain event. Bottom line: Confidence is increasing,
albeit slowly, in a decent rain event Wednesday into Thurday,
but confidence in amounts remains low and will hopefully be
assisted by the CAMs as this event begins to shift into their
window. Some showers linger through the day Friday, before
tapering off in the evening.

KEY MESSAGE 3 DESCRIPTION...
Global models are in surprisingly good agreement on the 500 mb
pattern going into next week. Low pressure exits to the east on
Saturday and a ridge builds making for a mostly dry day with
temperatures in the low to mid-80s. Shower and thunderstorm
chances return Sunday as a trough begins to approach, as usual
its broad brush at this time range, but it likely won`t be a
washout. Monday may be a different story as all the models have
an upper low somewhere in the vicinity, but of course it is to
early to say for sure. Bottom line: We may only get a brief
break in the wetter weather as the pattern looks to largely
remain unsettled.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...

Short Term /00Z Monday through Tuesday/...

Summary: Increasing moisture will bring some potential for low
clouds and fog towards daybreak Tuesday with shower and thunderstorm
chances increasing Tuesday afternoon and evening for NH for NH
terminals.

Restrictions: VFR all sites attm.  Increasing moisture will bring
the potential for MVFR CIGS to MHT/CON/PSM and possibly AUG with IFR
in fog and CIGs for LEB/HIE and RKD.  Conditions should improve to
VFR at least for a time by mid/late morning Tuesday and into the
afternoon before restrictions are again possible Tuesday afternoon
and evening due to SHRA/TSRA primarily for NH terminals.

Winds: Southeasterly winds diminish to 5kts or less overnight before
strengthening again to 10-15kts for the day Tuesday...diminishing
to less than 10kts Tuesday night.

LLWS: No LLWS is expected through the TAF period and through
Tuesday night.

Thunder: There remains a few showers in the vicinity of HIE this
evening with an isolated thunderstorm possible in the area before
quiet conditions tonight and through Tuesday morning.  Isolated to
scattered slow moving /movement generally from south to north/
thunderstorms are possible Tuesday afternoon and evening,
particularly for NH terminals.

Outlook:

Wednesday - Thursday: Slow moving low pressure will bring multiple
rounds of rainfall to the region with a prolonged period of IFR/MVFR
restrictions. Winds at or below 10kts.

Friday - Saturday:  Expect conditions to slowly improve on Friday as
low pressure moves away from the region though scattered showers and
a thunderstorm are possible.  VFR conditions should dominate
Saturday outside of an isolated afternoon shower/storm. Winds at
or below 10kts.

&&

.MARINE...
Sub-SCA conditions continue early this week as low pressure
closes off entering the Northeast. Some fog or marine stratus
development is likely tonight, and may continue into Tuesday.

Low pressure then moves through the region Wednesday and
Thursday, which may bring wind gusts near 25kts and seas to
around 5ft. Conditions should ease back below SCA criteria
Friday as low pressure exits.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.

&&

$$

DISCUSSION...Baron/Cornwell/Jamison
AVIATION...Arnott