Convective Outlook

U.S. Severe Weather Forecast

acus01 kwns 151939 
Storm Prediction Center ac 151938 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0138 PM CST Tue Jan 15 2019 

Valid 152000z - 161200z 

..there is a marginal risk of severe thunderstorms across parts of 
the coast in Southern California... 

A brief tornado and locally damaging wind gusts will be possible 
between 2 to 8 PM PST from Santa Barbara to Los Angeles counties in 
coastal Southern California. 

No changes are made to the outlook for this issuance. 

.Broyles.. 01/15/2019 

Previous discussion... /issued 1009 am CST Tue Jan 15 2019/ 

..Southern California... 
A low-amplitude shortwave trough located around 200 west-southwest of vbg will 
reach Santa Barbara County late this afternoon before shifting 
farther inland this evening. Convection along the coast downstream 
of this wave will remain low-topped through at least early 
afternoon. Thereafter, steepening mid-level lapse rates from west to 
east along with further low-level moistening should support a period 
of meager MLCAPE below 500 j/kg impinging on the coast. This will 
yield potential for about a 6-h window of isolated thunderstorms. 
Increasing speeds along with veering of the wind profile with height 
should Foster an enlarged hodograph with effective shear possibly 
reaching 35-45 kt. This would support a risk for a supercell or two 
capable of a brief tornado and locally damaging gusts near the 
immediate coast. 


Mesoscale Discussion

acus11 kwns 130855 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 130854 

Mesoscale discussion 0019 
National Weather Service Storm Prediction Center Norman OK 
0254 am CST sun Jan 13 2019 

Areas affected...central Virginia and Maryland...including southern 
portions of the Washington D.C./Baltimore Metro area 

Concerning...heavy snow 

Valid 130854z - 131300z 

Summary...moderate to heavy snow now developing across parts of 
central Virginia and Maryland is expected to persist through mid to 
late morning, with rates (around or in excess of 1 inch per hour) 
likely maximizing in the 6-10 am EST time frame. 

Discussion...a broadly cyclonic 50-70+ kt 500 mb jet streak 
continues to gradually develop eastward across the northern Gulf 
Coast states, with its exit region now beginning to nose to the Lee 
of the southern Appalachians, toward the southern mid Atlantic coast 
through mid to late morning. It appears an associated broad area of 
strong upward vertical motion will include a period of strengthening 
lower/mid-tropospheric frontogenesis across Virginia and adjacent 
portions of the mid Atlantic. 

Across central Virginia into adjacent portions of central Maryland, 
where temperature profiles are expected to remain entirely below 
freezing, models indicate that lift may begin to become maximized 
within the favorable mixed-phase layer for dendritic ice Crystal 
growth by daybreak, and continue through mid to late morning. Aided 
by relatively high precipitable water content (up to around .70 
inches), one or more bands of heavy snow, at rates around or in 
excess of 1 inch per hour, appear possible. Forecast soundings 
suggest that this may persist for a 3-4 hour period at any 
particular location, generally in a narrow corridor from the 
vicinity of the Blue Ridge, north of Roanoke VA, east/northeastward 
through southern portions of the greater Washington D.C./Baltimore 
metropolitan area. 

.Kerr.. 01/13/2019 

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


Latitude...Lon 38287888 38517861 38657841 38977644 38497624 37937809 
37697891 37767939 38087930 38287888 

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