textproduct: Binghamton

WHAT HAS CHANGED

Chances of precipitation were expanded tonight into Monday morning. Isolated to scattered snow showers may lingering into Monday afternoon as a shortwave drops south through the area and combines with steep low level lapse rates, instability (MUCAPE 100 J/kg) and lingering moisture in the surface to 750mb (0-2km) layer of the atmosphere. Conditions then dry out quickly by early Monday evening with clear skies after sunset as high pressure settles overhead and temperatures plunge into the upper 10s and 20s overnight.

KEY MESSAGES

1) Cold air mass in place through Tuesday morning with well below average temperatures and chances of snow showers tonight.

2) A gradual warm up is expected from mid week into the start of next weekend.

DISCUSSION

KEY MESSAGE 1...

With the cold front passage this morning, temperatures cooled a a couple degrees colder than forecast so snow was a bit more widespread with several inches of accumulation at higher terrain. The sun is starting to come out from west to east as the thick cloud cover moves east with the front. The sun will likely melt all the snow that accumulated today and warm areas that see sun before 3 pm into the low 40s. With the upper level trough axis still moving in, 500 mb heights are still falling with cold air advection in aloft. The combination of solar heating warming the surface and the cooling aloft will lead to unstable conditions this afternoon and evening. Scattered rain and snow showers will develop for much of the region with the stronger showers containing graupel and potentially some lightning if the updrafts can get deep enough before losing day time heating.

Tonight, lake effect snow develops as 850 mb temperatures fall to near -10C. Boundary layer shear is not favorable for organized banding but scattered snow showers will develop for most of CNY and the Finger Lakes into the Twin Tiers of NY/PA. Accumulation of snow will likely be limited to higher terrain and elevated surfaces and likely be less than an inch.

The cold airmass remains in place tomorrow, with high temperatures struggling to climb into the 40s. Forecast soundings show drier air advecting in aloft, but there should be enough lingering moisture in the 0-2km layer (up to 750mb) to allow for more isolated to scattered pop up showers as a shortwave rotates south through the forecast area. There remains uncertainty in the exact timing of this shortwave and subsequent showers. There is also uncertainty in how far and how fast it may move south into NE PA. Precip type will be mainly snow showers with very cold air aloft around -10C. The showers will eventually dissipate as the dry air aloft mixes down into the boundary layer, with conditions drying out and clearing by late afternoon or early evening.

The dry air, clear skies, and a surface high building in is going to lead to a very cold night Monday into Tuesday. Just for fun, the probability of lows being 25 degrees or colder on or after April 20th in any given year is around 2% for all climate sites so very anomalous for this late in the year if we do fall into the low 20s. KEY MESSAGE 2...

After a cold morning on Tuesday, the upper level trough is on its way east with rising 500 mb heights and 850 mb temperatures warming back above freezing by the afternoon. The rest of the week into the weekend is looking mostly dry outside of a frontal passage overnight Tuesday as a weak 500 mb shortwave moves through. There is no cold air advection behind this front so a gradual warm up is expected into next weekend, with highs back into the 60s and 70s and lows back above freezing. There is hints that we could be going back into a wetter pattern next weekend as ensemble 500 mb height anomaly means show a trough trying to set up in the western US and SW flow developing over the east.

AVIATION /00Z MONDAY THROUGH FRIDAY/

Mainly VFR conditions are expected overnight, there will however be a chance for scattered snow showers at times for our CNY terminals. Lake effect snow showers will have the potential to impact SYR and RME between 00-06z, with some occasion, brief MVFR restrictions as these showers move through. The showers then drop south and could impact ITH, ELM and BGM with some tempo MVFR restrictions between about 04-08z early Monday morning. VFR conditions then return for the early to mid morning hours Monday morning (09-14z). After 14z scattered snow showers are forecast to move through the area from north to south, potentially bringing another round of tempo MVFR restrictions to RME and SYR (14-18z) and ITH and BGM (16-23z). Confidence is only low to moderate in these snow showers materializing.

Northwest flow with light winds overnight. NW winds increase between 10-20kts heading into late Monday morning and afternoon, with a few gusts close to 25kts also possible.

Outlook:

Monday night and Tuesday...VFR conditons expected.

Tuesday night into Wednesday morning...Front approaches the region with restrictions possible.

Wednesday afternoon and Thursday...VFR conditions possible inbetween systems.

Friday...Chance for a few showers, mainly VFR. Isolated restrictions possible at times.

BGM WATCHES/WARNINGS/ADVISORIES

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