060516 Forecast

Mountain Area Forecast ( June 2-5 )

 ALERT For Locally Heavy Rain With Downpours In Showers & Thunderstorms From Thursday Into This Weekend ( Hit-Miss Coverage At Any Given Time ).  Some Storms May Be Strong To Locally Severe.

The Storm Prediction Center Has Issued A Slight Risk Of Severe Thunderstorms For The Area Between 8 AM Saturday and 8 AM Sunday

The threat for downpours in showers & thunderstorms will continue into Sunday ( and become likely Saturday Night Into Sunday ).  Remain alert for changing conditions during outdoor activities this weekend.

Overnight Into Thursday Morning

Chance of showers & thunderstorms.  Mostly cloudy.  Areas of dense fog.  Light and variable winds on mountain ridges and plateaus below 2700 feet.  Winds SSW-WSW 5-10 mph, with higher gusts, on mountain ridges above 2700 feet.  Warm & humid with temperatures mostly in the 60s.

Thursday Afternoon

Hit-miss showers & thunderstorms.  Locally heavy rainfall.  Winds SSW to WSW at generally less than 10 mph outside of storms.  Temperatures varying from upper 60s to low 70s in upper elevations to the mid 70s to around 80 degrees.

Thursday Night Into Friday Morning

A chance of showers & thunderstorms.  Locally heavy rainfall possible.  Areas of dense fog.  Winds SSW-WNW at generally less than 10 mph outside of storms.  Warm and humid with temperatures widespread in the upper 50s to lower-middle 60s.

Friday Afternoon

Hit-miss showers & thunderstorms.  Locally heavy rainfall.  Winds SSW to WSW at generally less than 10 mph outside of storms.  Temperatures varying from upper 60s to low 70s in upper elevations to the mid 70s to lower 80 degrees.

Friday Night Into Saturday Morning

A chance of showers & thunderstorms.  Locally heavy rainfall possible.  Areas of dense fog.  Light & variable winds along mountain ridges-plateaus below 2700 feet.  Warm & humid with temps in the upper 50s to lower-middle 60s.

*Some storms could become strong to locally severe during the Saturday afternoon into Sunday period.  Low-level flow will increase during Saturday Night into Sunday AM to also increase orographic forcing into favored zones such as that of the High Knob Massif-Black Mountain corridor.

Saturday Afternoon

Hit-miss showers & thunderstorms.  Locally heavy rainfall.  Winds SSW to SW at 5-15 mph, with higher gusts, along mid to upper elevation mountain ridges and plateaus.  Humid.  Temperatures varying from low-mid 70s at the highest elevations to the lower-middle 80s.

Saturday Night Into Sunday Morning

Showers & downpours in thunderstorms becoming likely.  Locally heavy rainfall.  Winds SSW to SW 5-15 mph, with higher gusts, along mountain ridges-plateaus below 2700 feet.  Winds SW-WSW 10-20 mph, with higher gusts, along mountain ridges above 2700 feet.  Temperatures from the upper 50s to mid-upper 60s.

Sunday Morning Into Sunday Afternoon

Showers & downpours in thunderstorms.  Locally heavy rainfall.  Winds SSW-WSW at 5-15 mph, with higher gusts.  Temperatures varying from the 60s to lower-middle 70s.

 

Weather Discussion ( May 31-June 4 )

Early Saturday Update

While hit-miss showers and downpours in thunderstorms will be possible Saturday, they will become likely during Saturday Night & Sunday as a cold front pushes east into the Appalachians.  Some storms could be strong to severe from Saturday afternoon into Sunday.

Early Summer Thunderstorms Form - High Knob Massif
Early Summer Thunderstorms Form – High Knob Massif
Reference Early Summer 2016 In The Appalachians for more photographs of dramatic skies above the High Knob Massif as thunderstorms began erupting Thursday afternoon ( June 2 ).
The High Knob Massif, especially central-eastern portions, have been a focus for heavy rainfall during the past few days.
Doppler 36-Hour Estimated Rainfall Ending 12:08 AM
Doppler 36-Hour Estimated Rainfall Ending 12:08 AM on June 3, 2016
Locations in the RED on the above graphic had an estimated 2.00″ to 3.00″+ of rainfall during the 36-hour period ending at just after midnight on June 3 ( 12:08 AM ).  The heaviest rains being focused upon the Little Stony Creek Basin ( from above Bark Camp Lake to along Little Stony Gorge ) and eastern sections of the Big Stony Creek Basin ( in the Glades ).
Strong water level rises, with ROARING whitewater, were observed on both Little Stony Creek and Big Stony Creek.
NAM 12 KM Model Total Rainfall Forecast
NAM 12 KM Model Total Rainfall Forecast Next 84-Hours

Forecast models continue to show an increasing coverage of showers-thunderstorms by later Saturday & Saturday Night into Sunday.

GFS Model Total Rainfall Forecast Next 84-Hours
GFS Model Total Rainfall Forecast Next 84-Hours

The GFS ( above ) keeps more of a hit-miss pattern while the NAM and European models forecast widespread coverage to develop into Saturday Night and Sunday.  The European is placing the heaviest rainfall corridor across far southwest Virginia and extreme southeastern Kentucky, as well as along portions of the lower Tennessee Valley and plateau.

Storm Prediction Center Risk Region To 8 AM Sunday
Storm Prediction Center Risk Region To 8 AM Sunday

The Storm Prediction Center has the entire area within a slight risk for severe thunderstorms between 8:00 AM Saturday and 8:00 AM Sunday.

Probability Of A Tornado Within 25 Miles Of A Given Point
Probability Of A Tornado Within 25 Miles Of A Given Point
Wind damage will be the greatest severe risk parameter, outside of always dangerous lightning and downpours of heavy rainfall.
Probability Of Wind Damage Within 25 Miles Of A Given Point
Probability Of Wind Damage Within 25 Miles Of A Given Point
Storm Prediction Center Discussion
Storm Prediction Center Discussion

An added factor will be increasing pressure gradient winds and enhancement of orographic forcing by Saturday Night into Sunday in advance of a upper air trough and surface cold frontal boundary.  This will favor a heavy to excessive rainfall potential for the High Knob Massif-Black Mountain corridor on general SW air flow trajectories.

Please remain alert to changing conditions this weekend and keep NOAA Weather Radio and mobile devices handy when outside to monitor the potential for strong to locally severe storms and heavy rains.

 

Previous Discussion

A summery air mass will remain in place across the Mountain Empire into this weekend with a array of  showers and downpours in thunderstorms.

Doppler Rainfall Estimate For Tuesday - May 31, 2016
Doppler Rainfall Estimate For Tuesday – May 31, 2016
The pattern observed during May 31-June 1 will be repeated, with an increasing coverage, into this weekend.  Downpours of 0.50″ to 1.00″+ have been observed and can easily occur in the stronger or more persistent activity on any given day.
Between 1.00″ and 2.00″ of rain fell from Bark Camp Lake across much of the Little Stony Creek Basin into the Guest River Gorge area during June 1 as persistent, back-building storms developed over eastern portions of the High Knob Massif ( below ).  Additional heavy action form along portions of Black & Pine mountains to the NW-N of Norton & SW of Pound.
Doppler Radar Rainfall Estimate For June 1
Doppler Radar Rainfall Estimate For Wednesday – June 1, 2016

While heating generally offers the best development, showers & downpours will not be restricted to just the daylight hours amid such a warm and buoyant air mass.

Scaly Vase Chanterelle ( Gomphus floccosus )
Scaly Vase Chanterelle ( Gomphus floccosus ) Grow Amid Wetness
A tropical air mass following a wet May has turned the mountain landscape into a temperate rain forest, with many creatures great and small actively pursuing their life strategies.
Hover Fly ( Syrphidae Family ) Working Coreopsis ( Coreopsis grandiflora )
Hover Fly ( Syrphidae Family ) Working Coreopsis ( Coreopsis grandiflora )

Forecast models continue to show the heavy rainfall potential, but struggle with placement of amounts.

NAM 12 KM Model Total Precipitation Forecast
NAM 12 KM Model Total Rainfall Forecast To 8 AM Sunday – June 5, 2016

The highest resolution version of the NAM looks like it has a bad rash, or case of the measles, as it attempts to forecast where the heaviest rainfall will fall.

NAM 4 KM Model
NAM 4 KM Model Total Rainfall Forecast To 8 AM Saturday – June 4, 2016

All models, including the European, are on board with the heavy to locally excessive rainfall potential through this upcoming weekend.

GFS Model Total Rainfall Forecast
GFS Model Total Rainfall Forecast – Next 5 Days

With luck, a drier and nice air mass will arrive for at least a while next week.

Stay tuned to NOAA Weather Radio for any possible watches and/or local warnings that may be needed through coming days.