U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 250537 
Storm Prediction Center ac 250536 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1236 am CDT Sat Oct 25 2014 

Valid 251200z - 261200z 

..there is a marginal risk of severe thunderstorms across parts of northern California and 
southwest Oregon... 

Scattered thunderstorms are expected to develop across northern 
California into southwest Oregon Saturday afternoon. A few storms 
may become capable of producing a weak/brief tornado across this 
region. Scattered thunderstorms will also develop across upstate 
New York into portions of northern New England. 

..Pacific coast... 

Late evening satellite imagery depicts a well-defined middle-level 
circulation off the northern California coast...centered near 39n/130w. This 
feature is lifting northeastward toward the Oregon coast and should move 
inland after 18z as 80-100kt 500mb speed maximum translates into eastern 
Oregon and weakens. Latest guidance suggests 12hr middle-level height 
falls on the order of 150m should spread across western Oregon into Washington 
during the day. While strongest large-scale forcing is expected to 
focus north of marginal risk region...southern extent of low-level 
convergence should extend into northern California where shear profiles will be 
more than adequate for sustaining organized updrafts. Primary 
negatives across this region will be modest lapse rates/meager 
buoyancy which should negate updraft intensity. Forecast soundings 
across northern California/southwestern Oregon suggest surface-based convection is possible 
and longer-lived updrafts could rotate...perhaps even briefly 
producing a few weak tornadoes. 

..nern u... 

Focused area of ascent within exit region of strong middle-level jet 
will spread into upstate New York after 18z. While moisture is quite 
sparse across this region...and 50f+ surface dew points remain 600mi 
upstream over WI...scattered convection is expected to develop along cold 
front during the late afternoon as lapse rates steepen within 
cooling middle-level profile. Forecast soundings across upstate New York 
suggest surface-based convection is likely despite the expected cool surface 
temperatures. In fact...cloud heights could exceed 6km and 
graupel/small hail may accompany much of this activity. Given the 
expected steep low-level lapse rates gusty winds may also occur with 
this convection. 

.Darrow/Dean.. 10/25/2014 

Mesoscale Discussion

acus11 kwns 151721 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 151720 

Mesoscale discussion 1899 
National Weather Service Storm Prediction Center Norman OK 
1220 PM CDT Wednesday Oct 15 2014 

Areas affected...central Maryland into southeastern PA 

Concerning...severe potential...watch unlikely 

Valid 151720z - 151945z 

Probability of watch issuance...20 percent 

Summary...an isolated strong wind gust or brief/weak tornado cannot 
be ruled out with storms as they develop northward from Maryland into southeastern PA. 

Discussion...an isolated strong cell with substantial vertical 
development continues to propagate northward along a north-S oriented boundary 
which extends into PA and links with an existing front across eastern PA 
which currently separates the more moist/unstable air to the southeast. 

This particular storm has had a persistent and broad circulation 
with it...but nothing particularly strong or tight probably due to 
weak low-level buoyancy/acceleration. While deep-layer flow is 
strong above the ground...most of the shear is relegated to the 
near-surface layer and other cells away from the outflow boundary 
have shown little if any shear. Therefore...any wind/tornados threat is 
expected to be brief...short-lived and isolated...and a watch is not 

.Jewell/corfidi.. 10/15/2014 

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


Latitude...Lon 39157664 39007677 38987688 39067699 39267696 39617690 
40007679 40347640 40457615 40407593 40137594 39617620