textproduct: Gray - Portland

WHAT HAS CHANGED

The frost/freeze headlines have ended as temps warm this morning.

KEY MESSAGES

1. Cold, continental high pressure will allow for chilly temperatures this morning and again tonight for some areas.

2. A rainy Sunday with below average temperatures.

3. Warming up again for next week with only isolated rain chances currently.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

A cool, dry air mass continues to settle towards the forecast area early this morning. High pressure remains in control for tonight, and conditions are slightly warmer aloft but largely unchanged from current. I suspect that the NBM temps are too warm and we should make another run at freezing in the northern valleys. I will continue to blend in some 10th percentile NBM temps and MOS guidance to bring those readings down.

KEY MESSAGE 2 DESCRIPTION...

High pressure will eventually lose the fight, and a rather broad surface low will lift northeast into New England by Sunday. Thus, we will see increasing chances of rain through the day before a gradual decrease in coverage from west to east on Monday. The best synoptic forcing should move through Sunday night into Monday morning which is when we will likely see the heaviest rain. Even then, amounts are expected to be fairly light. The latest NBM currently suggests medium to high probabilities (40 to 80 percent) for a quarter inch of rain or more across the southern half of New Hampshire and the foothills/interior of Maine. However, when we increase that threshold to a half inch, the QPF probabilities decrease into the low to medium (20 to 50 percent) range. Thus, confidence is fairly high that we will see widespread totals in the quarter to half inch range, but confidence for higher amounts are pretty low at this time.

Temperatures may struggle to stay in the 50s on Sunday given onshore flow off the chilly waters. Combined with wet conditions and increasing winds, it will feel quite raw. Will see a bit of a SE- oriented low-level jet lift northeast across the region, with 925 mb winds around 40 kts offshore. Not strong enough to be concerned about high winds on land, but this may allow for some ocean- enhancement and upslope precipitation enhancement given the orientation.

KEY MESSAGE 3 DESCRIPTION...

Showers may linger Monday but do not look widespread. Next week will feature a return to average-above average temperatures. As is common at this range, there are rather mixed signals for precipitation, but right now would favor widely scattered showers as opposed to any widespread soaking rain events.

The large-scale pattern becomes quite complex as guidance suggests an omega block developing next week. This would pump up a strong ridge to our northwest over central Canada, with troughing near or offshore the Northeast U.S. We may have some northern stream energy give shower chances with this configuration, but details remain fuzzy.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

Through Friday...VFR prevails tonight through Friday night. Light and variable winds tonight are likely to turn onshore for coastal terminals with sea breezes during Friday afternoon.

Outlook...

Saturday and Saturday night: VFR conditions expected to prevail though some MVFR CIGs may begin to creep in late Sat night.

Sunday and Monday: Periods of MVFR or lower begin Sun afternoon as CIGs lower and areas of rain move thru the region.

Tuesday: Gradual improvement to VFR expected.

Tuesday Night: VFR conditions expected.

Wednesday: VFR conditions expected, but local MVFR or lower possible in showers along a crossing cold front.

MARINE

High pressure will largely be in control of the region thru weekend. Winds and seas are expected to remain below SCA thresholds. The weak pressure gradient should allow for afternoon sea breezes to develop and turn winds onshore. Winds and seas may approach SCA thresholds Mon as a longer fetch onshore wind develops ahead of an encroaching warm front. Winds then become offshore by midweek as high pressure builds in from the west.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...None.