textproduct: Gray - Portland

WHAT HAS CHANGED

New aviation section for the 12Z TAFs.

Otherwise, no major changes needed but did tweak PoPs over the next few hours to better align with observations.

KEY MESSAGES

1. Rain continues through this morning with drying trend this afternoon. Other than the Pemigewasset River at Woodstock reaching minor flood stage and possibly the Saco at Conway and the Pemigewasset at Plymouth, rainfall rates have been low enough that the risk for additional flood products being needed is low.

2. The first weekend of the spring with widespread warmth and fair weather is expected this weekend. Water temperatures remain cold with inland lakes around 50F and ocean temperatures in the 40s so cold water safety messaging will likely be needed.

3. Expect above to well above normal temperatures on Sunday and through much of the work week. The warmest days will be Tuesday and Wednesday which may also bring some scattered afternoon/evening thunderstorms.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

An axis of light to moderate rainfall extends SSE to WNW across SW Maine through central NH early this morning with southern NH seeing little in the way of steady rain. This axis will continue to pivot to a west to east orientation and slowly sink south and weaken through mid morning. Peak rainfall amounts so far of 2-3 inches have occurred in the western White Mountains towards the Lakes Region of NH with this occuring over a 12+ hour period. Peak rainfall rates have generally stayed below 0.5 inches per hour with most areas under the axis of rain seeing rates of 0.1 to 0.25 inches per hour. Rainfall rates are expected to weaken into this morning so while some areas in the Whites may see upwards of 4 inches the risk for areal flood advisories/warnings appears low. This rainfall will bring the Pemi River at Woodstock to minor flood stage through early this morning where a River Flood Warning remains in effect.

The areas likely to additional rainfall of 1-2 inches will be from the eastern White Mountains through the foothills of western Maine and in and around Cumberland County. Rainfall amounts here so far have generally been around 1-2 inches so these areas will likely be able to handle the additional rainfall.

As an upper low slides south and east of New England today rain will taper off from NW to SE with mostly dry weather possible to the coast by late afternoon. Highs will generally be in the upper 50s to low 60s with more sun across the north.

KEY MESSAGE 2 DESCRIPTION...

Ridging aloft builds in for Saturday with surface high pressure centered south of New England. Mostly fair skies and southwest winds limiting much of a sea breeze will bring highs area wide into the 70s. A short wave crossing Quebec will bring increasing clouds across the north late in the day and may spark a few showers Saturday night. Ridging builds back into the area Sunday for another warm and mostly sunny day with highs in the upper 70s to low 80s.

KEY MESSAGE 3 DESCRIPTION...

On Sunday, we will gradually transition from zonal flow aloft during the day, to northwest flow in the evening as a ridge amplifies and approaches from the west. This pattern will keep temperatures on the increase with highs on Sunday forecast to range from the 60s and lower 70s north, to the upper 70s and low to mid 80s south. Temperatures will be similar on Monday but maybe a touch cooler east and a little warmer in the mountains.

Tuesday will likely remain dry through most of the day but we could see some more substantial height falls later in the afternoon/evening as we transition back into southwest flow aloft. A warm front will also lift north across the region. All of these factors could potentially lead to the warmest day of the year thus far with afternoon highs forecast to range from the upper 70s and lower 80s north, to the mid 80s across the Midcoast and most of western Maine, to the upper 80s and lower 90s over southern New Hampshire. Return flow should also lead to widespread dewpoints in the mid to upper 50s. With the very warm temperatures and increasing moisture, we should at least see a few hundred J/kg of CAPE in the afternoon with some 30 to 35 knot deep layer shear. As of right now, most of the precipitation on Tuesday afternoon/evening will mainly be in the mountains with a better chance for more widespread storms on Wednesday afternoon/evening as a cold front approaches. Instability may also be a bit stronger on Wednesday ahead of the front. We will have to keep an eye out for strong storms each afternoon/evening. As noted in the previous discussion, a small marine layer may limit strong thunderstorm activity near the coast.

Temperatures cool down a bit on Thursday, but will likely still be above normal for most locations across New Hampshire and western Maine.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

Through 12Z Saturday...A mix of restrictions ranging from LIFR to MVFR will continue this morning...owing to rain, fog, and low ceilings. However, most of the precipitation is expected across the western ME terminals. For this afternoon and evening, TAFs show trends toward improvement to MVFR and eventually VFR as ceilings lift and precipitation tapers off. However, confidence is low on timing of improvements. For tonight into early Saturday, mainly VFR but will have to watch for fog development due to recent rains and light winds.

Outlook:

Saturday/Saturday night: VFR conditions expected.

Sunday/Sunday night: VFR conditions expected.

Monday/Monday night: VFR conditions expected.

Tuesday/Tuesday night: IFR to MVFR restrictions possible in scattered afternoon/evening showers and thunderstorms.

MARINE

Northeast winds relax through the morning as low pressure pulls east of the Gulf of Maine. Seas from this system will build through today to 5-7 feet keeping SCA conditions in place through tonight. Winds shift southwest tonight into Saturday.

Southwest winds pick up to SCA levels from the southwest Saturday night, with 4-6ft seas expected. Winds and seas will gradually relax through the day on Sunday from west to east, with winds shifting to out of the west and then northwest by the evening. Winds become light and variable overnight into Monday with seas of 2-3ft expected early next week.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Small Craft Advisory until 8 AM EDT Saturday for ANZ150-152- 154.