textproduct: Binghamton

WHAT HAS CHANGED

Minor adjustments to timing of the incoming showers and thunderstorms on Sunday were made. Timing adjustments to linger showers and storms longer on Monday were also made. PoPs are increasing for the middle of the week as well, especially Wednesday and Thursday with deep moisture and plenty of instability likely to be in place.

KEY MESSAGES

1) High pressure will keep conditions mainly dry today with a mix of filtered sun and clouds.

2) The weather pattern turns unsettled Sunday and into Monday with locally heavy rainfall possible as a slow moving frontal boundary moves through the region.

3) A warm and humid pattern will persist Tuesday through Friday next week, with chances for a showers or thunderstorms each day.

DISCUSSION

KEY MESSAGE 1...

Some early morning valley fog is expected again today, as temperatures dip down into the mid-50s to mid 60s at daybreak. High level cirrus clouds will continue to overspread the area from west to east through the day, with GFS soundings showing the saturated cloud layer mainly between 20k to 35k feet agl, so a potentially rather thick layer. There also looks to be some scattered mid level cumulus clouds developing this afternoon closer to the 5-7K feet agl level. All in all, expect a mix of clouds and some filtered sunshine today. There looks to be enough sunshine and southerly warm air advection to boost high temperatures into the low and mid-80s. Dew points hold in the low to mid 60s, so it will feel slightly humid out there this afternoon. The 00z 3km NAM (which has been over done with low level moisture lately) is showing a few pop up showers or t'storms over the Catskills and eastern Susquehanna region later this afternoon, but most other CAMs are not showing this. Decided to hold PoPs below mentionable levels (10% or lower) today; so overall expecting a dry day areawide.

Tonight will be mainly cloudy, and still generally dry. Can't rule out a few isolated to scattered showers though as the next system gradually approaches from the west. With more clouds around, the patchy fog will be more limited, likely only over the Catskill valleys.

KEY MESSAGE 2...

A more established southerly flow of moisture will take hold over the area on Sunday. A warm front pushes through in the early morning, with a chance for a few showers along and behind this frontal boundary. Otherwise, it is looking mostly cloudy and humid on Sunday. The best instability looks to generally remain south and west of our forecast area, closer to the mid and upper level low/trough for most of the day. Late in the day, shower and thunderstorm chances to begin to increase as PWATs jump up to 1.75 inches over our Finger Lakes and Central NY regions. MLCAPE is expected to remain 500 J/kg or less over our CWA and deep layer shear is trending lower (under 25 kts for Central NY, up to 40 kts in NE PA). So at this time, not seeing a widespread severe thunderstorm threat, but some of the showers and storms could certainly produce heavy rainfall. As the trough and associated area of low pressure gradually shifts north and east toward our area, chances for rain and embedded thunderstorms increases Sunday night. PWATs rise between 1.8 to 2.0 inches overnight as well, and warm cloud layer depth increases to nearly 12k feet. This would increase rainfall efficiency due to the warm rain processes. It's too early to pin down exact rainfall amounts in this convective type of pattern, near the mid/upper level low.

Ensemble guidance is trending slower with the main frontal passage, as a piece of the upper level trough and low continue to spin over the Appalachians into Monday. There is uncertainty on just when a west-northwest wind shift will occur (with a frontal passage) that would start to decrease the moisture and instability levels. It appears much of Central NY and especially NE PA will remain under and moist and unstable atmosphere on Monday. The latest model guidance is showing PWATs between 1.75 to 2.0 inches lingering through at least the first half of Monday, before gradually decreasing from NW to SE later in the day. With this slower trend, kept likely PoPs for showers and thunderstorms (with a mention of heavy rain) over most of the forecast area into Monday afternoon. The likely PoPs fade to high chance back toward Syracuse, Penn Yan and Hornell where drier air may try to work in later Monday. Temperatures Sunday and Monday will be in the mid-70s to low 80s for highs, with overnight lows in the 60s. Surface dew points will be 65- 70 Sunday, rising into the upper 60s to mid-70s on Monday...this will make it feel very muggy and humid. With this type of air mass in place there remains a marginal to slight risk for excessive rainfall and isolated flash flooding Sunday afternoon through Monday for most of the area.

KEY MESSAGE 3...

It now appears the remnant upper level low may stall over the Tennessee Valley Tuesday, before lifting back north and east toward our area mid week. Depending on the exact position of this feature and timing, our forecast area may see a brief drier reprieve on Tuesday. This will depend on how far south the front makes it late Monday into Monday night. By Tuesday night and Wednesday it looks like moisture and instability levels will be increasing once again. This will keep showers likely and a chance for thunderstorms in the forecast Wednesday and Thursday, tapering to scattered showers and storms for the end of the upcoming week. Despite the showers and possible thunderstorms around, it will still be partly sunny, warm and humid much of the week. Highs will be in the 80s, lows in the 60s and afternoon dew points in the mid-60s to mid-70s each day.

AVIATION /10Z SATURDAY THROUGH WEDNESDAY/

Once lingering fog clears out of ELM, all terminals will be VFR this TAF period. Isolated, pop up showers will be possible around AVP this afternoon but confidence is too low to mention showers. Rain showers will also be possible early Sunday morning though there is some uncertainty on timing. Winds will be out of the south to southeast. Sustained speeds will be 5 to 10 kts with gusts up to 15 kts possible at BGM and ITH tonight.

Outlook:

Sunday through Monday...Rain and restrictions likely, with a chance for thunderstorms, as a moist frontal system passes through the region.

Tuesday...Mainly VFR; low chance for showers and restrictions.

Wednesday...Chances for scattered showers and isolated thunder; associated restrictions.

BGM WATCHES/WARNINGS/ADVISORIES

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