Jon Marker

@MJ33Wx What are the biggest differences in terms of performance between the HRRR and RRFS that you have noticed?

@WX_Marker RRFS exists with a FV3 core, but yes, it is going to MPAS core. Most NCEP models will be moving to MPAS cores for a unified model system. NAM will eventually get retired, but not sure on date.

In reference to the day 3 outlook for 3/11/2026. I have seen an uptick in social media posts utilizing the RRFS for convective forecasting. It's not a model that I would use (1/2) #kywx

@MJ33Wx I thought RRFS was based off MPAS? Is the NAM still expected to be discontinued soon?

I have been involved in evaluating these models in the hazardous weather testbed where we compared them to the MPAS cores. Again, MPAS was way better, but the RRFS initialization is pretty good. Just tends to go off the rails later in the run.

This leads to effective snow growth and heavy snowfall rate

What's impressive with this overall set up is the abundant transport of moisture into a very cold, arctic air mass. Up to 1-inch of QPF is something this is not common across the Ohio Valley with arctic air!

Long way to go with this one! Snow goes all the way back to Texas and will stream across the Ohio Valley through Sunday. Expect to see some rippin snowfall rates overnight with bands of heavy snow with 1 in/hr.

What makes this set up impressive is the massive 3 sigma arctic high pressure that presses the arctic air south. This is key to creating a widespread overrunning precipitation event, which is being enhanced by more phasing of the SW disturbance.

Incredible! Very impressive winter storm develops across the S. Plains and heads across the Ohio Valley and Northeast with far reaching impacts of heavy snow and icy conditions. #winterstorm

This is a very impressive set up for an overrunning precipitation event. Significant snow and ice could be quite expansive with arctic air surging south.

A significant winter weather event is increasingly possible later this week/weekend as arctic air presses south and sets up a strong temperature gradient. Potential for widespread, significant snow and ice from the S. Plains --> Eastern US. #energy #natgas #agwx

Significant band of lake-effect snow occurring across northern Indiana tonight. Godspeed to the plow driver driving through it! 🫡#inwx #lakeeffectsnow #heavysnow

A strong cold front plows through Thursday night with a big swing in temperatures. However, I’m puzzled by the hype over a “flash freeze” in the Ohio Valley. There is several hours of windy, lower dew point air prior to deep cold 🤷‍♂️

@webberweather Is wonder how this will compete with the blocking retrograding west over the Hudson Bay 🤔

The first significant positive East Asia Mtn Torque event of the season will occur late next week into the following week. This will yield a strong, extended Pacific Jet Stream (+EPO) in late Oct & encourage MJO/CCKW propagation across the Maritime Continent & West Pacific

Last night, the 53rd Weather Reconnaissance Squadron flew into the eye of Hurricane Erin—and captured imagery of the breathtaking stadium effect. These missions provide critical data to the NHC to improve forecasts, helping keep communities safe before the storm makes landfall.#readynow #weatherready

Upscale growth occurring near Sioux Falls …reports of wind gusts 75 mph+. This MCS will propagate ESE through the overnight. #agwx #sdwx #iowa

Ridge builds across the S. Plains next 10 days with a hot and dry pattern across Plains. Active/stormy pattern continues across the Midwest. Full details in today's reports! #agwx #corn #heat

@RepMTG I’m a meteorologist - feel free to reach out

I am introducing a bill that prohibits the injection, release, or dispersion of chemicals or substances into the atmosphere for the express purpose of altering weather, temperature, climate, or sunlight intensity. It will be a felony offense. I have been researching weather modification and working with the legislative counsel for months writing this bill. It will be similar to Florida’s Senate Bill 56. We must end the dangerous and deadly practice of weather modification and geoengineering.

Forecast models continue to highlight relatively favorable temperatures across the core of the AG Belt through mid-July with no support for a heatwave over the next 10 days. #agwx #corn #soybeans

Good riddance!! As the last wave of rain slides through, a time lapse of precipitation over the last few days. #flooding #agwx

While there is still significance to this line of thunderstorms (not downplaying it at all), models didn’t do so hot with the convection. Afternoon supercells/discrete cells did not materialize. It’s easy to lose sight of the fact that models are still tools.

The last few runs of the HRRR paint a very concerning picture across Indiana into Ohio. It fires discrete storms ahead of the main line. Discrete cells along & especially ahead of the cold front would be in a very conducive environment for strong tornadoes. 1/2