U.S. Severe Weather Forecast (Convective Outlook)

Day Three

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Storm Prediction Center ac 270539 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1239 am CDT Wednesday Jul 27 2016 

Valid 271200z - 281200z 

..there is a marginal risk of severe thunderstorms across northern New England... 

..There is a marginal risk of severe thunderstorms across the plains... 

..there is a marginal risk of severe thunderstorms across the middle Atlantic... 

..There is a marginal risk of severe thunderstorms across southeastern Arizona... 

Strong thunderstorms may impact parts of the Central Plains...the 
High Plains...the middle Atlantic coast region...southeastern Arizona 
and northern Maine on Wednesday...with some risk for severe weather. 


Large-scale pattern will continue to favor stronger flow near and 
north of the international border Wednesday as prominent upper low 
progresses into qc. Southern influence of this trough will affect 
convection across northern New England while deepening northwesterly flow across 
the High Plains enhances the potential for a few organized storms 
over this region. Elsewhere...a few strong storms may develop in 
the middle Atlantic and desert SW during the heat of the day. 

1. New England. Seasonally strong middle-level flow will extend 
across qc into northern New England...well ahead of surface front that should 
remain north of the border through peak heating. Latest short-range 
guidance suggests isolated thunderstorms will evolve along the boundary 
across qc and this activity could spread into northern ME by early 
evening. Gusty winds and marginally severe hail are possible. 

2. Plains. With upper ridge expected to hold over the Great 
Basin...northwesterly flow should persist across the High Plains during the 
day1 period. Weak short-wave ridging is expected across Wyoming during 
the day...primarily in the wake of an early-day mesoscale convective system that is 
spreading southeastward across Nebraska. Leading edge of this activity 
should be near the Kansas border by daybreak and for this reason have 
adjusted 5 percent severe probs south a bit to account for a more 
southern extent to outflow/surface front. Diurnal heating will be the 
primary factor in isolated thunderstorm development during the day 
from southeastern Montana into eastern Colorado. In the absence of meaningful large-scale 
ascent...topography will influence initiation. Large hail/damaging 
winds may be noted with the strongest storms. 

3. Middle Atlantic. Strong surface heating will once again contribute 
to robust thunderstorm activity across portions of the middle Atlantic. 
With westerly flow on the order of 20kt this activity could exhibit 
loosely organized multi-cell updrafts...though storm mergers and 
high precipitable water air mass would primarily be responsible for generating 
locally damaging wind threat. 

4. Arizona. Northeasterly 500mb flow around 20kt will be noted across nm into 
southeastern Arizona as upper ridge remains centered over the Great Basin. Gusty 
winds could certainly be noted with convection as it propagates off 
the higher terrain toward lower elevations. 

.Darrow/Gleason.. 07/27/2016 


Mesoscale Discussion

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sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 270550 

Mesoscale discussion 1404 
National Weather Service Storm Prediction Center Norman OK 
1250 am CDT Wednesday Jul 27 2016 

Areas affected...ecntrl Nebraska 

Concerning...severe potential...watch unlikely 

Valid 270550z - 270745z 

Probability of watch issuance...5 percent 

Summary...an isolated wind damage threat may continue for another 
hour or two with marginally severe wind gusts possible. The threat 
should gradually decrease over the next couple of hours and ww 
issuance is not expected. 

Discussion...latest surface analysis shows a corridor of low-level 
moisture from southeastern Kansas extending north-northwestward into central Nebraska where surface 
dewpoints are in the middle to upper 60s f. Moderate instability is 
located on the western edge of the moist airmass across western and central 
Nebraska with a quasi-linear convective system ongoing along the eastern edge 
of moderate instability. The Hastings WSR-88D vwp has 0-6m shear 
near 40 knots which may support a marginal severe threat with a few 
damaging wind gusts possible over the next hour or two. 
However...the line will continue to move into weaker instability 
over southern and eastern Nebraska which will contribute to disorganization of the 
line with time. 

.Broyles/grams.. 07/27/2016 

..please see www.Spc.NOAA.Gov for graphic product... 


Latitude...Lon 42449847 41609885 41019940 40769975 40459958 40189896 
40139778 40989700 42149712 42449847