NOAA Storm Prediction Center

Convective Outlooks

Convective Outlooks
The convective outlooks serve as guidance to the local NWS forecast offices and are used by emergency managers, private sector meteorologists, media, and other weather customers concerned with public safety. Three separate risk areas (slight, moderate, and high) are used to describe the expected coverage and intensity for the categorical severe weather threat on days 1-3 along with severe weather probabilities for the potential threat.

Day 1 Outlook Day 2 Outlook Day 3 Outlook Days 4-8 Outlook

Day 1 Outlook Convective Tornado
Hail Wind
Categorical Day1 1200Z Outlook
  
Images courtesy of the NWS Storm Prediction Center
 Forecast Discussion


000
ACUS01 KWNS 180545
SWODY1
SPC AC 180544

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
1244 AM CDT Mon Jun 18 2018

Valid 181200Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
NORTHEAST...

...SUMMARY...
Strong to locally severe thunderstorms will be possible across the
Northeast later today. Isolated severe storms may also develop west
along a front into the central Plains.

...Northeast...

Weak mid-level height falls are expected to spread across
southeastern Canada into New England during the day1 period ahead of
a notable short-wave trough. Latest model guidance suggests a plume
of high PW, approaching 2", will spread across southern ON/QC ahead
of a surface front that should approach the international border by
late afternoon. Extensive frontal convection will be noted along the
boundary as it surges southeast toward upstate NY/New England.
Forecast soundings ahead of the wind shift suggest some
boundary-layer heating will occur but 3-6km lapse rates will remain
quite weak with values likely remaining on the order of 5.5 C/km. As
a result, poor mid-level lapse rates will negate meaningful hail
production and damaging winds should be the primary risk with
convection as it spreads southeast into this region. Have maintained
15% severe probs across stronger-forced regions of the Northeast
with lower probs west along the trailing boundary. This activity
will likely spread into southern New England into parts of the
northern Middle Atlantic during the evening hours.

...Central Plains/Mid-MS Valley...

Latest water-vapor imagery depicts a weak short-wave trough over
eastern NM lifting north-northeast in line with latest model
guidance. This feature will advance into central NE by early
afternoon before topping the ridge over MN/IA during the overnight
hours. Convection should once again develop along the northwestern
periphery of the ridge along a frontal zone draped across the
central Plains into northern IL. There is some concern that higher
severe probs may be needed immediately ahead of the weak short wave,
most likely over eastern NE/western IA where boundary-layer heating
could be maximized. If confidence in air mass destabilization over
this region increases then a SLGT risk may be needed.

Isolated strong/severe convection may also develop along the Front
Range of CO into extreme southeast WY where post-frontal upslope
flow will be maximized. Substantial boundary-layer cooling across
the High Plains will limit destabilization to the corridor
immediately in the lee of the higher terrain.

..Darrow/Squitieri.. 06/18/2018

$$