- Day Three
acus01 kwns 041301
Storm Prediction Center ac 041258
Day 1 convective outlook
National Weather Service Storm Prediction Center Norman OK
0758 am CDT Sat Jul 04 2015
Valid 041300z - 051200z
..there is a slight risk of severe thunderstorms over parts of the northern and Central
..there is a slight risk of severe thunderstorms over parts of the central Gulf
..there is a marginal risk of severe thunderstorms from the northern High Plains to the
Southern Plains and from the lower MS valley to the Carolina CST...
..there is a marginal risk of severe thunderstorms over parts of the Great Basin...
a few severe storms with large hail...damaging winds...and possibly
a tornado are expected over parts of the northern and Central Plains
late this afternoon and evening. Storms capable of locally damaging
wind and heavy rain are expected over central Gulf Coast states.
More isolated strong to severe storms will affect the Southern
Plains...Georgia...the Carolinas...and the Great Basin.
Great Basin/southern rockies ridge/eastern U.S. Trough pattern will prevail
through sun. Moderate westerly flow with several embedded disturbances
will continue over the northern rockies and northern/Central Plains...on NE side of
the ridge. One notable disturbance within the eastern trough...now
entering northwest Arkansas...will track east across the lower MS/lower Tennessee valleys
tonight/early sun...while several weaker impulses precede it across the
Very moist air /pw 1.75-2.00 inches/ will persist from the Southern Plains
east/NE to the middle/S Atlantic CST. Sufficient moisture for storms also
will be present over the central and northern plains...where precipitable water will remain
at or above 1.25 inches.
..cntrl Gulf CST states to Carolina CST this afternoon...
Morning radiosonde observation and vwp data Sample seasonably strong /30-40 knots/ west-southwesterly
middle-level flow over region...associated in part with Arkansas upper impulse.
Combination of modest surface heating...increasing large-scale ascent
with upper disturbance...and hi precipitable water may Foster development of
occasional bowing segments this afternoon with a risk for locally damaging
wind...mainly with new storms forming along and S of existing west-east
outflow boundary that at this time extends from far northern la to west central Georgia.
More isolated strong gusts may persist into tonight as embedded bowing
segments continue east into GA/SC. Farther east...a more conditional risk
for locally damaging wind may evolve over parts of SC and eastern NC this
afternoon...where convergence will be limited but somewhat stronger
heating will occur beneath lingering axis of stronger flow
associated with surface wave/upper impulse departing the NC CST.
..nrn/Central Plains this afternoon into tonight...
Strong heating amidst ample moisture will promote substantial
destabilization today along and ahead of Lee trough over the
northern/Central High plains. More modest destabilization is expected over
the northern High Plains...along weak cold front associated with western Canada
A few storms may form toward midday...associated with lead upper
impulse now over the western Dakotas. Additional development should
occur later this afternoon southward across western Nebraska into northwest Kansas...with secondary
disturbance tracking southeastward from Montana. Storms also may form near the
Black Hills...and along the cold front in northern/eastern Montana. Some of the
Dakotas/neb/NW Kansas convection may evolve into discrete supercells
capable of large hail...damaging winds...and a
tornado or two. The Dakotas/neb/KS activity should merge into one or
two small mcss that persist into early sun.
..srn plains this aftn/eve...
Weak northwest/southeast front and related convective outflow boundaries will once
again serve to focus afternoon/evening storm development over parts of OK and
Texas. Large-scale forcing for ascent will remain weak...and the 850 mb
flow slightly divergent. Nevertheless...presence of very
moist/unstable low-level air beneath relatively cool middle-level
temperatures...and modest but vertically-veering wind
profiles...will yield an environment conditionally favorable for
isolated to perhaps widely scattered strong updrafts. A supercell or two could
form and...given strength of buoyancy...these would be capable of
..grt basin this aftn/eve...
Surface heating and ascent associated with an impulse moving north-northwest around
western side of upper ridge should yield fairly widespread diurnal storms
over much of central and northern Nevada. Coupled with steep low to middle-level
lapse rates...isolated strong to severe wind gusts and/or small hail may
occur as the activity organizes into small...nwd-moving clusters.
acus11 kwns 032236
sels mesoscale discussion
Storm Prediction Center mesoscale discussion 032236
Mesoscale discussion 1293
National Weather Service Storm Prediction Center Norman OK
0536 PM CDT Friday Jul 03 2015
Areas affected...portions of central MS...central Alabama...and far west-central
Concerning...severe potential...watch possible
Valid 032236z - 040000z
Probability of watch issuance...40 percent
Summary...isolated strong to damaging wind gusts remain possible
through the early evening. Large hail may also occur with any
discrete storms. Depending on storm coverage and intensity over the
next several hours...ww issuance is possible.
Discussion...a convectively reinforced outflow boundary currently
bisects the mesoscale discussion area from west to east...lying roughly across central MS
into central Alabama. A warm...moist airmass remains in place over the
region...with temperatures generally in the lower to middle 80s and
dewpoints in the lower 70s to middle 70s contributing to MLCAPE of
1500-2500 j/kg per rap mesoanalysis. Enhanced middle-level flow of
35-45 knots present on area vwps suggests convection developing along
the outflow boundary may acquire sufficient organization to support
mulitcell and occasional supercell structures. Once such supercell
that has moved from Bibb into Chilton County Alabama has produced large
hail up to 1.50 inch in diameter.
Another cluster of thunderstorms moving eastward over west-central MS may be
associated with a remnant mesoscale convective vortex from convection last night in OK.
Given sufficient effective bulk shear of 35-40 knots...this activity
may pose more of a strong/damaging wind threat as it continues
moving over central MS with time. If the activity along the remnant
outflow boundary and/or the cluster of storms in west-central MS increase
in coverage and intensity over the next several hours...then a
Severe Thunderstorm Watch may be needed.
..please see www.Spc.NOAA.Gov for graphic product...
Latitude...Lon 32759105 33399101 33789043 33698828 33528628 33408514
31968469 31778518 31908768 32239027 32759105