Mid-June Sleet-Drifts? Severe Threats, Heavy Rain Potentail and A/C Alert!
No worries… this sleet isn’t that close to home and it’s around 6,288ft. Any guesses? Thanks to the Mt. Washington Observatory Facebook page for the picture below. Tuesday weather atop the summit boasted a mid-June “sleet-drift”. YIKES! It’s too early for me to start thinking about sleet/snow, let’s move on!
“Surprise! Colder-than-expected temperatures have resulted in on-and-off showers of ice pellets (sleet) over the last half-hour or so, resulting in the formation of a mid-June “sleet-drift” on our observation deck.”
See more from Mount Washington Obervatory HERE:
Thundery Outlook Continues
Thanks to stormchasingvideo.com for the image below in Brush, CO from earlier this week. I’d say that this is an example of what not to do. Kids playing around in a hail storm… It might seem like a fun idea at first until someones takes a large chunk of ice to the noggin, not to mention the threat of lightning in the area.
Here’s another shot from stormchasingvideo.com where hail piles look more like snow piles! I know how hard it is drive in snow drifts, I couldn’t imagine driving in hail drifts.
Thunderstorm activity was quite common across the country on Monday, June 17th. Here are some of the stormy pics from earlier this week.
I though this was interesting… Take a look at how widespread thunderstorm activity was on Monday, June 17th. Even most Canada recorded lightning! Hawaii, California, Nevada and Arizona were the only U.S. states that didn’t record lightning. Pretty wild huh?!?
Severe Threat Wednesday
The SPC has a SLIGHT RISK of severe weather across parts of the HIGH Plains on Wednesday ahead of that Pacific Northwest low pressure system. Hail and high winds look to be the primary threat along with heavy rainfall potential, but an isolated tornado can’t be ruled out.
…NRN ROCKIES/NRN HIGH PLAINS…
LEE CYCLOGENESIS WILL INDUCE THE CONTINUED NWWD TRANSPORT OF
MOISTURE INTO THE NRN HIGH PLAINS AND FEATURE 50S BOUNDARY LAYER
DEWPOINTS. STRONG SURFACE HEATING AHEAD OF THE APPROACHING
MID-LEVEL DISTURBANCE AND VERY STEEP MID-LEVEL LAPSE RATES /8-9 DEG
C PER KM/ WILL RESULT IN 1000-2500 J/KG MLCAPE BY PEAK HEATING
ACCORDING TO THE LATEST MODEL DATA. EXPECTING ISOLD-SCTD STORMS TO
DEVELOP BY THE MID AFTERNOON AND MOVE IN A GENERAL NWD DIRECTION
OWING TO THE MERIDIONAL CHARACTER TO THE MID-UPPER FLOW. THE
PRESENCE OF STEEP LAPSE RATES AND SIZABLE CAPE IN THE -10 TO -30 DEG
C LAYER SHOWN IN FORECAST SOUNDINGS WOULD SUPPORT A LARGE TO VERY
LARGE HAIL THREAT EVOLVING WITH THE MORE INTENSE UPDRAFTS
/SUPERCELLS/. THE PROPENSITY FOR COLD POOLS TO COALESCE TOWARDS
EVENING MAY INCREASE THE SEVERE WIND GUST THREAT AS CLUSTERS OF
STORMS MOVE FROM CNTRL MT TOWARDS THE CANADIAN BORDER AND NERN MT
DURING THE EVENING HOURS.
Severe Threat Thursday
…NRN PLAINS…UPPER MIDWEST…
GIVEN THE AFOREMENTIONED DISCREPANCIES IN THE HANDLING OF THE
SYNOPTIC PATTERN…CONFIDENCE IS LOW FOR HIGHLIGHTING SIGNIFICANT
SEVERE OR HIGHER COVERAGE PROBABILITIES ATTM. IT APPEARS THAT AN MCS
WILL PROBABLY BE ONGOING AT 12Z/THU INVOF MT/ND/SASKATCHEWAN BORDER.
THIS MAY CONTINUE TO MOVE EWD WITHIN MODERATE MID-LEVEL WLY FLOW AND
PERHAPS REDEVELOP/INTENSIFY E/SEWD INTO THE DIURNAL HEATING CYCLE
WITH ALL MODES OF SEVERE POSSIBLE GIVEN A MODERATE TO STRONGLY
UNSTABLE DOWNSTREAM AIR MASS. A STOUT CAPPING INVERSION AND
EXPANDING EML SHOULD LIMIT DIURNAL DEVELOPMENT WITH SRN EXTENT ALONG
ANY OUTFLOW AND CONFINE ACTIVITY MAINLY TO PARTS OF ND AND NWRN MN.
LOW-LEVEL WAA WILL STRENGTHEN THU NIGHT WITH A ROBUST LLJ FROM THE
SRN PLAINS TO THE MID-MO VALLEY. ALONG THE LEADING EDGE OF THE
CAPPING INVERSION…EITHER A CONTINUATION OF DIURNAL CONVECTION OR
DEVELOPMENT OF A RENEWED MCS APPEARS POSSIBLE WITH ATTENDANT SEVERE
Severe Threat Friday
I still think Friday could be an interesting day ahead of the slow moving low pressure system. The Midwest could be in line for scattered thunderstorms, which may be severe… There is one thing, however, that could prevent thunderstorms from developing. The image below suggests how much energy or CAPE (Convective Available Potential Energy) will be present by midday. The big red blob over the Midwest would be considered significant potential energy for thunderstorms.
“CAPPED” on Friday??
One question remains about Friday and that is: Are temperatures aloft going to be too warm? A wedge of warmer air aloft would actually help to keep the thunder threat at bay. Yes, sometimes it can actually be too warm to thunder! A ‘general’ rule of thumb for a “Capping Inversion” is 10°C at 700mb. Anything warmer than that and thunder potential would be less likely. Anything cooler than that an thunder may be possible under given circumstances. 10°C at 700mb is also possible to overcome depending on circumstance too, so as I mentioned… Friday could be interesting late in the day for some folks across the far north if that “Cap” can be eroded. Stay tuned!
Upcoming Rainfall Potentail
NOAA’s HPC 3 day rainfall forecast suggests a couple of pockets of heavy rainfall potentail through the end of the week. One located in the Southeast as a front lingers with shower and thunderstorm potential and another in the northern tier of the nation from the Pacific Northwest to the Midwest as that slow moving low traverses the international border.
Additional Weekend Precipitation
On top of what we get through the rest of the week, some folks could stay fairly wet through the weekend, espeically those in the Midwest as the slow moving storm/front stalls. Several shower and thunderstorm chances will continue into the weekend there. A 5 day precipitation total from some in the Midwest by the end of the weekend could end up being as much as 1″ to 2″+
Sticky Weather Ahead…
Summery temps and humidity values will be on the rise over the next several days. I could see a big chunk of the nation in the 80s and 90s with dew point values in the uncomfy zone. The image below shows the dew point forecast midday Friday in the Humid and Uncomfy zone.
Thanks for checking in and have a great rest of your week
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