Midday Zones Update: Heavy Rainfall and Severe T-Storm Threat This Afternoon

Happy Thursday! Low pressure currently over the Ohio Valley is attempting to push warm front north form Mid-Atlantic region. But instead a triple-point low will form over Mid-Atlantic region, along the warm front.  A strong low-level jet, mid-level vorticity, low-level moisture convergence with firehose of Atlantic and subtropical moisture will lead another rounding of heavy rain with embedded thunderstorms. Especially south and west of NYC.

Rainfall totals between 1″ to 2″ are likely for parts of the region. Locally heaver rainfall totals are possible with heavy downpours or thunderstorms training in some areas. This could result in some localized flash flooding, especially in poor drainage and low-lying areas. Due heavy rainfall over past couple of weeks, some rivers and stream flooding may also occur.

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HRRR showing heavy bands of rain coming through this afternoon

There is some concern for some high winds with a 50-70kt southerly low-level jet moving through the region. But stout 850mb-925mb inversion should keep stronger winds aloft from mixing down to surface. But a tight pressure gradient will cause sustained winds between 20 to 30mph with  gusts between 40-50mph, especially near the coast. The National Weather Service has issued a wind advisory for New Jersey coast, for these winds. Onshore winds will also possibly cause some minor coastal flooding at high tides this evening. Heavy rainfall could also exacerbate this flooding.

Also there is low chance that some thunderstorm may become strong or severe, mainly over Central and Southern NJ and Southeast PA. The warm front will be moving northward through those regions faster this afternoon. So the airmass may destabilize further this afternoon in those areas. Strong wind fields will support deep-layered shear and large scale forcing will contribute to thunderstorms possible with isolated damaging wind gusts. Low-level winds backing along the warm front and low LCL heights may support an isolated weak tornado. If fact, the Storm Prediction Center has just issued severe thunderstorm watch for parts of Central and Southern NJ  and Southeast PA until 5pm this afternoon.

Storm Prediciton Center with a marginal risk for many coastal areas this afternoon. Slight risk further south over the Mid-Atlantic coast

Storm Prediction Center with a marginal risk for many coastal areas this afternoon. Slight risk further south over the Mid-Atlantic coast

More unsettled weather is likely into  Friday, as the large closed upper-level low still swings through region. Then as the upper-level low weakens and lifts into the Canadian Martimes,  high pressure will build in the region. Clouds will clear on Saturday with highs in lower to middle 50s. Then more sunshine on Sunday will lead to highs in the lower to middle 60s.

A large trough over Western US, will cause stronger ridge build over the Eastern US early next week. This will lead warmer than normal temperatures, with southwest flow. Highs could possible mid-upper 70s to near 80 in spots. Another frontal system and upper-level for later next week. More showers could arrive by Wednesday evening, Then some cooler weather could arrive again late next week.