Monday, April 24, 2017

Periods of Rain On The Way

It's been a little bit since my last blog post but now that the mid-spring break is over full-time coverage will resume.  A coastal low will slowly lift north Tuesday bringing periods of rain, wind, and minor coastal flooding through Wednesday AM.  Behind the low temperatures will soar into the low to mid 70's, peaking near 80 on Sunday.

General Overview
On satellite, we see a large storm just off the South Atlantic Coast.  It has a tropical connection that stretches into the Caribbean Sea.
NCEP/NOAA/NWS GOES_East Water Vapor Satellite Loop
There is a lot of rain falling in the Carolina's this afternoon.  Flash and River Flood watches and warnings have been posted throughout this region.
NWS Southeast Regional Radar Loop 
This will slowly track to the north thanks to high pressure protecting the northeast.  Here is the surface chart for 8 PM tonight.
WPC Surface Fronts/Precipitation Monday 8 PM
This high will work with a building ridge in the Northwest Atlantic to keep this low around longer than it is welcome.  Most ocean storms quickly race to the Atlantic Canada and into the Graveyard of the North Atlantic.  Just like humans, weather systems also have to deal with traffic.  This NW Atlantic "block" literally slows down the entire jet stream, which conceptually can be thought of as the "highway" for storm systems.
12z EURO 500 mb height anomaly Tuesday 2 PM (image Weatherbell)
The storm will lose forcing as it travels up the coast (and moves from mature to decay phase) but there will be plenty of drought denting rain for the region.

Short Term Forecast
Some light rain showers will break out in the pre-dawn hours.  Here is the simulated radar from 9 AM Tuesday until 9 AM Wednesday at 3-hour intervals.
12z NAM hires simulated radar 24 hr beginning Tuesday 9 AM ending Wednesday 9 AM (image Weatherbell)
  The steadiest rain will fall after 3 PM tomorrow.  Temperatures will only max in the mid to upper 40's for some of the region.  Others will get into the low 50's but with the wind out of the east, it will feel raw.
NWS Max Temps Tuesday (image Weatherbell)
That east wind will also allow for some water rises along the east and south facing beaches.  Overall, coastal flooding will be minor.  However, the tides are already astronomically high so the introduction of an ocean storm will create a few headaches.  Winds will gust 30-40 MPH for much of New England on Tuesday afternoon and evening.  Winds will approach 45-55 MPH in SE MA Wednesday as the low tracks slowly North.
WPC Surface Fronts/Precipitation Wednesday 8 AM

Temperatures won't fall much tomorrow night but the rain will linger into Wednesday AM.  Total rain will be over 1" for most east of the Connecticut River.
WPC/NWS Forecast Precipitation through Wednesday 1 PM
Although it has been dry the past week or so there is a low chance of flash flooding tomorrow, according to the Weather Prediction Center (WPC).
WPC Excessive Rainfall Outlook 8 AM Tuesday to 8 AM Wednesday
Temperatures will be near 60 on Wednesday before getting back into the 70's on Thursday, Friday, and Saturday.

-Zack Green

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