SPC AC 302012

   Day 1 Convective Outlook CORR 1
   NWS Storm Prediction Center Norman OK
   0312 PM CDT Tue May 30 2017

   Valid 302000Z - 311200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS CENTRAL PA
   INTO UPSTATE NEW YORK...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE MID
   ATLANTIC NORTHWARD...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER COASTAL
   SOUTHEAST LOUISIANA...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
   KANSAS INTO MISSOURI...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER EAST
   CENTRAL COLORADO INTO WESTERN KANSAS...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER CENTRAL
   OREGON AND WASHINGTON...

   CORRECTED FOR GRAPHICS

   ...SUMMARY...
   A few severe thunderstorms capable of large hail, damaging winds,
   and perhaps a brief/weak tornado will be possible this afternoon and
   evening from the lower Great Lakes and Adirondacks to North
   Carolina. Elsewhere, a few strong/severe storms may occur across the
   central Plains/Ozarks, central Gulf Coast, and Pacific Northwest.

   ...Northern VA northward across PA and NY...
   Previous forecast remains largely on track with strong to severe
   storms across central PA into NY. Strong heating also continues
   farther south across western MD into VA, where a pocket of mid 60s
   dewpoints remains. Several CAMs suggest a few strong cells
   developing later this afternoon, spreading southeastward across
   northern and east central VA. The long hodographs suggest mainly
   single cell mode with hail the main threat, although gusty winds are
   always possible. Eastward extent of the threat will be limited by
   cooler capped air mass roughly along and east of the D.C. area. 

   ...Eastern CO into western KS...
   Added a small Marginal risk for hail and wind for expected isolated
   development this afternoon. Visible imagery shows substantial CU
   fields around Limon eastward, and continued heating should yield a
   few storms. Northwesterly flow aloft combined with steep lapse rate
   profiles should allow storms to travel southeastward into Kansas.

   ...Southern LA...
   Extensive rain and storms continue across much of southern LA, with
   the strongest activity along the coast where better inflow exists
   off the Gulf and with less outflow/overturning. Thus, have nudged
   Marginal risk southward for a brief/weak tornado or wind threat.

   ...Eastern KS into MO...
   Best instability currently exists across Kansas, with drier air over
   northern MO, and have shunted northern extent of the Marginal risk
   south. Visible imagery shows good CU development over eastern KS as
   of 20Z, and a few cells are expected with hail or wind. Other
   activity continues into northern AR, with sporadic marginal hail
   cores noted on radar.

   ..Jewell.. 05/30/2017

   .PREV DISCUSSION... /ISSUED 1045 AM CDT Tue May 30 2017/

   ...NY/VT/PA/MD/VA...
   Only minor changes have been made to the ongoing forecast in this
   area.  Visible satellite imagery shows a corridor of daytime heating
   occurring from central NY into western PA, then southward into
   western MD and northern VA.  12z model guidance remains consistent
   that scattered thunderstorms will form in this region, aided by an
   approaching shortwave trough now over MI/IN/OH.  Afternoon CAPE
   values of 1000-2000 J/kg and rather strong west-southwesterly mid
   level winds will promote rather fast-moving thunderstorms capable of
   damaging winds and some hail.  The eastern extent of the severe
   threat should be strongly limited by the cool/stable environment
   over eastern NY/PA/MD/VA.

   ...LA...
   Radar loops have shown several rotating storms off and just along
   the coast of central/southeast LA.  This activity may persist for
   several more hours, posing a risk of a brief tornado or damaging
   wind gust.

   ...Southern MO/Northern AR...
   A remnant area of weak convection is tracking across southeast KS. 
   Model solutions suggest some intensification may occur with this
   activity by mid/late afternoon, with a risk of an isolated severe
   cell or two.  Gusty/damaging winds and hail would be the main
   threat.

   ...Eastern KS/Northern MO...
   A weak surface cold front is sagging southward across IA/NE.  This
   boundary may be a focus for scattered showers and thunderstorms this
   afternoon and evening.  Relatively steep low level lapse rates and
   sufficient vertical shear indicate a risk of an isolated severe
   storm or two capable of gusty winds and hail.

   ...WA/OR...
   A well-defined shortwave trough is approaching the Pacific Northwest
   coast.  Strong heating is forecast over parts of central WA/OR, with
   afternoon temperatures warming through the 80s and into the 90s. 
   Steep low and mid level lapse rates and sufficient southwesterly
   flow aloft suggest a risk of high-based showers and thunderstorms
   capable of gusty and locally damaging wind gusts.

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