textproduct: Binghamton

WHAT HAS CHANGED

Dew points were lowered on Thursday as model soundings show slightly drier conditions at the surface than suggested by NBM guidance.

KEY MESSAGES

1) Dry and pleasant conditions are expected today.

2) The pattern becomes more active beginning Wednesday with potential for strong storms late this week.

DISCUSSION

KEY MESSAGE 1...

A ridge of high pressure will remain in place today and lead to dry and pleasant conditions. Once the fog clears this morning, skies will be sunny as temperatures will climb into the upper 70s to mid 80s. Dew points will only be in the 50s, so humidity will be low. Overnight, temperatures will fall into the 50s and low 60s. With light winds and mostly clear skies, fog is expected to develop once again.

KEY MESSAGE 2...

While the ridge will still be in place come Wednesday, models are showing a wave or two riding this ridge. Dry air in place looks to keep things dry early in the day. With the high pressure just off the coast, the flow around the high will advect moisture northward over the region Wednesday afternoon, supporting showers and thunderstorms as the waves move through. Models differ on the solutions as the GFS has been consistent with conditions staying dry with a wave moving through earlier in the day. Also, there is some question on the amount of instability and whether or not a cap holds. Either way, this forecast will favor the majority of most guidance and keep chances for showers and storms present.

Moisture increases Thursday as a weak disturbance approaches the region and eventually moves through. PWATs will approach 2 inches over the region. In addition, MLCAPE is modeled to be 1000 to 1500 J/kg. Flow in the mid-levels will be fairly weak though strong enough for 0-6 km bulk shear to be 20 to 30 kts. Conditions will be favorable for thunderstorms to develop and a few strong ones cannot be ruled out. DCAPE values are high in model soundings, though weak low-level flow would suggest that there won't be much for winds to mix down. Still, given the high PWAT values and rich moisture, it may be possible to get wet microbursts. Seeing the long, skinny CAPE, small hail may also be possible. Of course, with this moisture- rich system, the main concern would be locally heavy rainfall and isolated flash flooding. The AHPS total precipitation accumulation over the last 7 days is 200 to 400% above normal across parts of the region, especially in the Twin Tiers and Catskills Regions. Despite a couple of dry days, it likely will not be enough for significant improvements to the antecedent conditions leading up to Thursday.

The broad trough over the Central US will drift east as the high pressure slides further out to sea. As this trough moves into the region, it flattens with flow becoming more zonal. Another disturbance will move through to support another round of showers and thunderstorms with conditions very similar to Thursday. With high PWATs, fairly high instability, and modest shear, the same hazards will be in place. Based on GFS soundings, there may be potential for slower moving showers on Friday into Saturday. For both days, WPC has had a Marginal Risk for excessive rainfall and that is likely to continue throughout the week.

Additional rounds of showers and thunderstorms will be possible this weekend, though forcing will be weaker and moisture is bit more limited. Remaining in the zonal flow, a wave moves through on Saturday. With drier air moving in, the heavy rain potential will be limited as PWATs are modeled to be lower. Instability will be present though shear may be weak, so confidence is low for the potential of stronger storms at this time. A weak frontal boundary then sweeps through on Sunday with another round of showers, though there is uncertainty with the timing. Then as we enter early next week, there is no change to the overall pattern, so Monday will continue the streak of consecutive days with chances for showers in the forecast.

Throughout this period, conditions will be warm and humid. Highs will be in the 80s and lows will be in the 60s. For early August, this near average though some days may be slightly above. Heat index values in the 90s will be possible in the valleys at the end of the week. Depending on the timing of showers and the amount of cloud cover during the daytime hours, temperatures may be slightly cooler than forecasted.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

Valley fog will hang around for about an hour or so after sunrise before burning off. ELM and BGM are expected to be impacted until around 13z. Afterwards, VFR conditions expected at all terminals through the 12z TAF period.

Outlook:

Tuesday night...Mainly VFR; possible valley fog at ELM.

Wednesday through Saturday...Scattered showers and isolated thunder; associated restrictions possible.

BGM WATCHES/WARNINGS/ADVISORIES

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