Jump to content
  • Member Statistics

    Total Members
    Most Online
    Newest Member

2022 Spring/Summer Mountains Thread

Maggie Ace

Recommended Posts

Flooding concerns increasing this afternoon for the Mountains 


Mesoscale Precipitation Discussion 0692

NWS Weather Prediction Center College Park MD

1255 PM EDT Sat Aug 06 2022


Areas affected...Southern and Central Appalachians


Concerning...Heavy rainfall...Flash flooding possible


Valid 061700Z - 062300Z


Summary...Slow moving showers and thunderstorms will continue to

develop across the Appalachians this aftn and evening. These

storms will be slow moving and contain rain rates of 1-2"/hr.

Flash flooding is possible.


Discussion...The GOES-E IR imagery this aftn in conjunction with

the regional radar mosaic indicates an expansion of showers and

thunderstorms from the southern terminus of the Appalachians

northward through the Panhandle of WV. These storms are developing

in an environment of extremely favorable thermodynamics

characterized by PWs of 1.7-2 inches, and collocated SBCAPE of

2000-3000 J/kg. A shortwave noted on WV imagery moving eastward

out of Kentucky is working in tandem with a weak mid-level trough

overhead to enhance ascent, while return flow around high pressure

centered over the Carolinas is converging into the terrain while

advecting higher moisture northward. Although convection is just

starting to intensify, radar estimated rain rates are already

1-1.5"/hr on local radars.


The presence of the trough aloft to steepen lapse rates combined

with weak height falls/PVA, upslope ascent, and robust instability

will fuel rapid development and expansion of convection through

the aftn. The high-res guidance is in good agreement that

convection will become widespread, generally across the higher

terrain, but maintain pulse-behavior as 0-6km shear remains 20 kts

or less. The elongated trough aloft and high pressure centered

near the Carolinas will keep overall flow weak, and storm motions

are progged to be just 5-10 kts from the SW across the area. At

the same time, as low-level flow veers more to the south, Corfidi

vectors are progged to become more opposed to the mean flow

suggesting an enhanced backbuilding or training threat, with

additional slow motion possible where terrain influences impact

storm initiation. These slow moving/training storms will likely

have rain rates of 1-2"/hr, which could produce 1-3" of rainfall,

with pockets of even higher amounts possible as reflected by the

HREF neighborhood probabilities.


24-hr rainfall according to MRMS has been 1-2" with pockets of

more than 3", adding to rainfall that has been as high as 200% of

normal the past 14 days. This has compromised FFG to as low as

1-1.5"/3hrs in the terrain, which the HREF indicates has a 40-60%

chance of being exceeded. Scattered instances of flash flooding

are possible through loss of heating, with the greatest risk

occurring where slow moving/training storms fall atop these

saturated soils in the more sensitive terrain.








Link to comment
Share on other sites

  • jburns unpinned this topic

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Create New...