U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 270517 
Storm Prediction Center ac 270515 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1115 PM CST Monday Jan 26 2015 

Valid 271200z - 281200z 

..no thunderstorm areas forecast... 

thunderstorms will remain unlikely across the Continental United 
States on Tuesday. 

A large upper trough will continue eastward off the East Coast with surface 
low drifting northward toward Nova Scotia. A cool and dry air mass will 
remain behind this system...with a high pressure ridge from the 
Great Lakes southward across the MS valley. 

To the west...a weak and Delaware-amplifying shortwave trough will affect the 
Great Basin with sufficient moisture for general precipitation. 
However...little if any instability will be present for deep 
convection...and anything more than a rogue lightning strike appears 

.Jewell.. 01/27/2015 

Mesoscale Discussion

acus11 kwns 270928 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 270928 

Mesoscale discussion 0045 
National Weather Service Storm Prediction Center Norman OK 
0328 am CST Tuesday Jan 27 2015 

Areas affected...southeastern New York...CT...RI...MA...srn New Hampshire and southeastern ME 


Valid 270928z - 271430z 

Summary...heaviest snow bands with occasional rates of 2+ inches per 
hour will persist through the early morning from eastern Long Island northward 
through eastern CT...Rhode Island into parts of central and eastern Massachusetts. Farther north 
snow will gradually increase with occasional 2+ inches per hour 
rates from southern New Hampshire through eastern Maine through 15z. Immediately 
surrounding the heaviest bands...snowfall rates up to 1 inch per 
hour at times will persist next several hours. 

Discussion...as of 09z the heaviest snow bands with rates of 2+ 
inches per hour have reorganized from eastern Long Island northward through 
eastern CT...Rhode Island into central/eastern Massachusetts and southeastern New Hampshire. This band of snow is 
associated with a zone of low-middle level frontogenetic forcing and 
deep-layer ascent along a north-S oriented deformation axis. WV imagery 
and rap analysis show a compact vorticity maximum just south of Long 
Island situated within the left exit region of a strong upper jet 
over the western Atlantic. As these features continue northward...zone of 
strongest ascent will gradually develop through southeastern New England 
including southeastern Maine through the early morning. In addition to heavy 
snow...the northeasterly low level jet is expected to increase to 70+ knots over southeastern New 
England within gradient zone between the northward-moving offshore surface low 
and high pressure over southeastern Canada. Surface winds will continue to gust 
in excess of 50 knots in this region. 

Area of higher reflectivity near Nantucket appears to indicate a 
heavy wet snow as a warm nose aloft advects westward along the intense 
low level jet. Some of this snow might occasionally mix with sleet from 
Nantucket Island and possibly northward to eastern Cape Cod...but the 
predominant precipitation type will probably remain snow. 

West of the heavy snow band from northern New Jersey through New York City into 
western CT and western Massachusetts...snowfall rates are expected to remain generally 
less than 1 inch per hour. 

.Dial.. 01/27/2015 

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


Latitude...Lon 40697362 42287293 44537053 45466813 45106726 44526732 
43306992 41687012 40367216 40697362