Skip Navigation Links weather.gov 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
The Weather Prediction Center

 
 

 

Follow the Weather Prediction Center on Facebook Follow the Weather Prediction Center on Twitter
NCEP Quarterly Newsletter
WPC Home
Analyses and Forecasts
   National High & Low
   WPC Discussions
   Surface Analysis
   Days ½-2½ CONUS
   Days 3-7 CONUS
   Days 4-8 Alaska
   QPF
   PQPF
   Flood Outlook
   Winter Weather
   Storm Summaries
   Heat Index
   Tropical Products
   Daily Weather Map
   GIS Products
Current Watches/
Warnings

Satellite and Radar Imagery
  GOES-East Satellite
  GOES-West Satellite
  National Radar
Product Archive
WPC Verification
   QPF
   Medium Range
   Model Diagnostics
   Event Reviews
   Winter Weather
International Desks
Development and Training
   Development
WPC Overview
   About the WPC
   Staff
   WPC History
   Other Sites
   FAQs
Meteorological Calculators
Contact Us
   About Our Site
 
USA.gov is the U.S. Government's official web portal to all federal, state, and local government web resources and services.
 
WPC Met Watch

 
Mesoscale Precipitation Discussion: #0587
(Issued at 1235 AM EDT Fri Jul 12 2019 )

MPD Selection
 


Graphic for MPD #0587

Mesoscale Precipitation Discussion 0587
NWS Weather Prediction Center College Park MD
1235 AM EDT Fri Jul 12 2019

Areas affected...Southern New England

Concerning...Heavy rainfall...Flash flooding likely

Valid 120435Z - 121030Z

SUMMARY...Showers and thunderstorms are expected to develop and
expand in coverage over the next few hours across southern New
England. Given the anomalous pool of moisture over the region, and
intense rainfall rates, some pockets of flash flooding will be
possible.

DISCUSSION...The latest GOES-16 IR/WV imagery is showing an axis
of improving large scale ascent over the region as upper level
divergence increases in response to the arrival of an upstream
shortwave trough and associated jet streak. Cloud tops have been
tending to cool across southern New England, and the latest radar
imagery is beginning to show some expansion of shower activity
across CT, RI and western MA. GLM from GOES-16 is not showing any
lightning activity as of yet over these areas, but the column over
the region is becoming very moist with upstream 00Z RAOB data out
of KOKX showing a deeply moist adiabatic sounding with a PWAT of
2.12 inches, a wet-bulb freezing level over 14000 feet, and nearly
800 j/kg of CAPE. All of this is reflective of a deep warm and
tropical-moist sounding.

Over the next couple of hours, larger scale ascent should increase
across southern New England as stronger shortwave energy arrives
and interacts with a retreating warm front across the region. In
fact, the latest 00Z hires guidance favors development of a weak
area of low pressure near the western tip of Long Island by 06Z.
This will help to facilitate stronger low-level convergence across
Long Island and adjacent areas to the northeast across southern
New England.

The result should be the development of shower and thunderstorm
activity that will be capable of producing very heavy rainfall
rates given the deeply warm/moist column that is advancing over
the region. Warm rain processes within a column of strengthening
low and mid-level omega fields should promote enhanced rainfall
efficiency with rates that may locally exceed 2 inches/hr.

The 00Z HREF suite of guidance favors locally as much as 2 to 4
inches of rain going through 09Z, with the last couple runs of the
HRRR even wetter with as much as 3 to 6 inches of rain. A
consensus of the guidance supports the heaviest swath aligning
across central CT up, the northern part of RI, and across
south-central/southeast MA (although not including the Cape).

Given the observational soundings and latest satellite/radar
trends, expect locally very heavy rains over the next several
hours to arrive which will include the suburbs and bigger
metropolitan areas along and adjacent a line from Hartford, CT to
Boston, MA. Some areas of flash flooding will be likely overnight
given the expected rainfall rates and storm totals.

Orrison

ATTN...WFO...ALY...BOX...GYX...OKX...

ATTN...RFC...NERFC...

LAT...LON   43177083 42747058 42387049 41977076 41527130
            41387160 41247228 41217281 41277342 41757327
            42467229


Last Updated: 1239 AM EDT Fri Jul 12 2019
 

NOAA/ National Weather Service
National Centers for Environmental Prediction
Weather Prediction Center
5830 University Research Court
College Park, Maryland 20740
Weather Prediction Center Web Team
Disclaimer
Credits
Glossary
Privacy Policy
About Us
Career Opportunities
Page last modified: Wednesday, 13-May-2015 19:29:02 GMT