Mountain Area Forecast ( July 3-5 )

The Chance For Showers & Downpours In Thunderstorms Will Be Increasing From  Independence Day Through This Week

Some thunderstorms could be strong to locally severe with the Storm Prediction Center issuing a slight risk for severe thunderstorms during Monday into Tuesday.

Severe Thunderstorm Watch In Effect Until 9:00 PM Monday ( Independence Day ) of July 4, 2016

A heavy-excessive rainfall potential, with the possibility of dangerous flash flooding, is increasing for locations along and now south of the Ohio River.  People living and driving along streams, and in flood prone locations, will need to be alert for the possibility of heavy rainfall from Monday PM Through Tuesday ( July 4-5 ) and again later in the medium range period ( into next week ).

 

Overnight Into Sunday Morning

Partly to mostly cloudy.  Chance of sprinkles or a shower.  Areas of valley fog.  E-SE winds at 5-15 mph, shifting S to W by morning, on middle to upper elevation mountain ridges.  Temperatures mainly in the 60s.

Sunday Afternoon

Partly to mostly cloudy.  Hazy and more humid with a chance for hit-miss showers & thunderstorms.  Light and variable winds.  Temperatures varying from the low-mid 70s in upper elevations to the lower-middle 80s ( warmer south toward the Tennessee Valley ).

Sunday Night Into Monday Morning

Partly to mostly cloudy.  Hazy.  Chance of showers & thunderstorms.  SSE-SW winds 10-20 mph, with higher gusts, along mid-upper elevation mountain ridges.  Mild with temperatures in the 60s to around 70 degrees.

Monday Afternoon ( Independence Day )

Partly to mostly cloudy with a chance of showers and downpours in thunderstorms.  Some storms could be strong to locally severe.  SSW-SW winds 10-20 mph, with higher gusts.  Temperatures varying from 70s in upper elevations to the 80s across lower-middle elevations ( hotter to the south toward the Tennessee Valley ).

Monday Night Into Tuesday

A chance of showers & downpours in thunderstorms.  Some storms could be strong to locally severe.  SSW-SW winds 10 to 20 mph, with higher gusts, along mid-upper elevation mountain ridges & plateaus.  Warm & humid with temps varying in the 60s to lower 70s.

 

Weather Discussion ( July 2-5 )

Early Monday ( July 4 ) Discussion

Reference June 2016 Climate Data for a recap of recent rainfall data ( more information will be added in coming days ).

A battle is ongoing amid the atmosphere across the eastern USA as opposing forces clash, with developing drought to the south over the Tennessee Valley and southern portions of the Appalachians being in contrast to recent severe flooding in parts of West Virginia and central Virginia.

This makes the ultimate outcome of the next 1-2 weeks more uncertain than typical, with signals increasing for another major rainfall-flood & flash flood event for somewhere in the surrounding region.

The Storm Prediction Center has expanded the slight risk to now include much of the mountain region between 8 AM on Independence Day ( July 4 ) and 8 AM on Tuesday ( July 5 ).

In addition, the Weather Prediction Center has now issued a risk for excessive rainfall with the axis of heaviest rains in recent hours developing well south of the global models to the west in Kentucky ( with up to 5.00″ of rainfall reported in Murray, Ky., near Land Between The Lakes ).

The latest European Model, just completed at 3:00 AM on Monday, is forecasting the axis of heaviest rains to now be along and southward of the Ohio River across Kentucky into central-southern West Virginia ( impacting or being very close to the Cumberland Mountains in southwest Virginia ).

Rainfall will come in waves, with clusters of storms, during this week into next week along the periphery of blazing heat to the south and southwest of the region.

The Bottom Line…A prolonged period of stormy weather conditions are expected at times during the next 5-10 days, with clusters of showers & downpours in thunderstorms moving across the region.  Some of the storms could be strong to severe.  Ultimately, the greatest danger is likely to be heavy-excessive rainfall amounts.  Dangerous to potentially life threatening flooding could again occur somewhere in the region.

It is not yet possible to tell exactly where dangerous flooding may develop, so please stay tuned to NOAA Weather Radio and your favorite media sources for updates and possible watches and warnings that will be likely through coming days.

The European Model mean rainfall axis is from southern Indiana and northern-central Kentucky to central-southern West Virginia, versus the WPC which has the axis orientation more SSW-NNE.  In both it would again put the recently flood ravaged corridor within West Virginia at an enhanced risk.  Only time will tell where the actual corridor develops, with the entire region needing to remain alert given unseasonably high moisture values forecast through coming days ( always an ominous signal in July ).

 

Previous Discussion

A relatively nice Independence Day Holiday Weekend is being enjoyed amid the mountains, with MAX temps on Saturday ( July 2 ) only reaching the 70s to lower 80s in locations along and north of the High Knob Massif and Tennessee Valley Divide.

Although showers were only isolated in nature, clouds were abundant and helped to hold temperatures down with specific MAXS on Saturday reaching 76 degrees at Nora 4 SSE and 80.9 degrees in Clintwood.

The MEAN daily MAX temperature during June 1-28 at the official National Weather Service station, relocated again to the campus of the University of Virginia’s College At Wise, was 80.9 degrees     ( around 10 degrees Fahrenheit above average daily MAXS at the summit level of the High Knob Massif ).

So far during 2016 there have been no official 90 degrees days in Wise and no 80 degree days along the highest mountain crestlines amid the High Knob Massif and Black Mountain.

Focus now shifts to another dangerous weather pattern, similar in nature to the one that produced historic flooding in West Virginia during June, with renewed surges of heat and deep, tropical moisture streaming into the Ohio Valley and Appalachians.

SSW-WSW winds will be increasing across mid-upper elevations of the Cumberland Mountains in coming days as a low-level jet again develops to pump in moist, unstable air.

While individual models are varying in rainfall amounts and placement over the short and longer term periods, a trend for heavy to excessive rainfall along and north of the Ohio River is initially being given.

Once again locations from the Cumberland Mountains north are at highest risk for heavy rainfall during the upcoming week; however, this will need to be closely followed as the development of convection will alter the atmosphere over time and could skew amounts ( at least locally ) away from the MEAN corridor shown below.

The pattern continues to feature a notable heat ridge and developing drought to the south versus much cooler air toward the north.

Temperature differences are even showing up locally between the Cumberland Mountains and the much hotter Tennessee Valley, toward TRI-TYS-CHA ( as observed in recent days and weeks ).

Clusters of showers and downpours in thunderstorms will again fire along the periphery of blazing heat to the south and southwest, with movement along the edge of the heat dome during coming days.  Where training occurs, or any back-building, will dictate where dangerous, potentially life threatening flooding once again evolves.

While there will likely be a main corridor of highest flood threat, more localized flash flooding could also occur anywhere in the mountain region where thunderstorms train or back-build.

In addition to the increasing heavy rainfall threat, a chance for some thunderstorms to become strong to locally severe will have to be respected.

Please stay tuned to NOAA Weather Radio and your favorite media sources for possible watches and/or warnings which may be needed in coming days.