textproduct: Binghamton

WHAT HAS CHANGED

Only minor changes were made to PoPs, QPF and temperatures through the middle of the week with this forecast update. The system at the end of the week is trending warmer and wetter with all rain now expected for our forecast area. A Marginal Risk for Excessive rain and severe thunderstorms is now indicated for the northwestern portion of the area Tuesday into Wednesday.

KEY MESSAGES

1) Staying mainly dry and seasonably mild through Monday afternoon.

2) Unsettled weather returns Monday night into next weekend as a series of low pressure and frontal systems affect the region. Uncertainty in the timing and placement of frontal boundaries will impact temperature gradients and where the steady to heavy rain falls. Thunderstorms and locally heavy rain will also need monitoring from Tuesday through Friday, as will the responses on smaller river systems.

DISCUSSION

KEY MESSAGE 1...

It stays dry, partly cloudy and mild this evening into tonight with lows only dipping down into the mid-30s to low 40s areawide. Monday will see some morning sunshine followed by increasing afternoon clouds. As a weak mid level wave moves overhead there could be a few scattered showers or sprinkles in the afternoon as well. Otherwise, it will be warm and a little breezy with southwest winds 8-15 mph and a few gusts up around 20 mph. High temperatures reach the upper 50s to low 60s, which is around 10 degrees above average for late March.

KEY MESSAGE 2...

An active weather pattern will set up across the US for much of the weak as a trough develops over the western US and the Bermuda high slides eastward, allowing the Gulf to open and moisture to flow into the central US. As pieces of this western trough eject east- northeast our area looks to be impacted with multiple rounds of rain.

First a period of light to moderate rain showers is likely to move through the area Monday night along a developing warm front. Expect between about a tenth to quarter inch of rain from this feature.

Confidence continues to increase for showers and storms Tuesday and Wednesday as a low pressure center passes to the north. Most of our area is expected to be well into the warm sector south of a front on Tuesday. Model soundings show abundant moisture, (PWATs in the 1.0- 1.5 range) with modest amounts of MLCAPE available (up to 500 J/kg) as some midday to afternoon clearing is possible. SPC does have the western half of our area under a Marginal Risk; this will be highly dependent on seeing any clearing and daytime heating. The latest trends in the guidance are warmer for Tuesday, with highs in the upper 60s to mid 70s. WPC Excessive Rainfall Outlook for Day 3 (Tues- Weds) suggests a Marginal risk of heavy rain generally along and north of the NY Southern Tier, where rainfall rates could exceed the very low flash flood guidance (anything more than 1-2 inches in a 6 hour period could start to cause issues).

These signals are indicated along the warm/stationary front and track of the main surface low...but we'll also have to be cognizant of any pre-frontal convection over the rest of CNY and NE PA. Ensemble mean guidance continues to suggest the frontal passage will occur Wednesday morning or midday but how far south the front moves before stalling is still unclear, and it could still be over NE PA Wednesday afternoon. Temperatures are trending much warmer Wednesday afternoon across NE PA, where it is forecast to reach 70-75 degrees.

The front barely makes it into southern PA or the northern Mid- Atlantic Wednesday evening before it lifts back north as a new warm front on Thursday. This will bring another round of rain and showers to the area through Thursday night...with yet more rain potential on Friday as the center of the low and eventual cold front press through the area. The latest guidance continues to show the cold front washing out a stalling as it approaches the Mid-Atlantic states due to that strong Bermuda High off the coast. This will open the door for a third system to bring more rain over the coming weekend. It does looks like behind this weekend system a stronger front will finally clear out the higher PWATs and moisture for a while. Also bringing a short period of cooler temperatures as well.

There are a lot of variables associated with each of these systems, however the simple fact that each system may stack more and more water across our increasingly sensitive watersheds lends careful watching. Hydrologic ensembles continue to show medium chances for minor flooding at some of the headwater points, with even a low probability (5-10%) to reach moderate stage flooding if everything comes together. Something to keep a close eye on in the coming days.

AVIATION /19Z SUNDAY THROUGH FRIDAY/

VFR conditions are expected at all terminals through the entire TAF period (at least through 18Z Monday). Weak LLWS will be possible at all terminals late tonight/early Monday morning, before dissipating at around 12Z Monday.

Outlook:

Monday morning through Monday early afternoon...Mainly VFR.

Monday late afternoon through Thursday...a chance of rain showers and associated occasional restrictions possible. Thunder possible each afternoon starting Tuesday afternoon.

Friday...Scattered rain showers and associated occasional restrictions possible.

BGM WATCHES/WARNINGS/ADVISORIES

PA...None. NY...None.