GaWx

0Z GFS is a big hit of a mix in SE GA/S SC: Kuchera snow IP: ZR:

0Z GFS qpf: fairly similar to 18Z

0Z GFS early maps look pretty similar to 18Z fwiw.

Houston started having sleet at 8PM EST/7PM CST. I wonder how that compares to the timing of the qpf start on various models.

0Z ICON: slight SE shift vs 18Z 0Z 18Z was a little to the NW of 0Z

It’s important that current dewpoints be compared to modeled dewpoints: Example: KATL actual 9PM DP is 0F What do models show for 9PM there? 0Z 3K NAM: way up at +14F! It’s 14F too high! 0Z NAM 12K: +10F (10F too high) 18Z Euro: +3F (only 3F too high…so very close) 18Z GFS is -10F (10F too low) So, 18Z Euro is by far the closest for KATL. You guys might want to check your locations as dewpoint will be very important in determining how long it will be virga. For here, Euro is spot on making it easily closest to reality like at KATL.

0Z NAM going north means more sleet and ZR down here on it: now may go ahead and charge my backup power packs in case ZR ends up dominating and is heavy sleet: would undoubtedly be alltime record IP by far in SE GA: some of this is off the top end of the chart! @dsaur

Compare that to 0Z NAM radar as of 9PM: And 10PM radar as if 10PM: p

0Z NAM a good bit further N!

Yep: this is 10:1…so higher amounts possible northern portion

If it comes in early, it could start as early as ~2 hours before this map, which is for the hour 3-4PM. So, say as early as ~1PM. Models have been speeding up the start and precip often starts a couple of hours earlier than models suggest:

Coldest Euro weekly for SE US for any week I’ve ever seen. This is for today through Sunday (1/20-26): coldest is 18-19F BN in darkest shade on Gulf coast meaning they’re having normals for St. Louis near 32! Further N around ATL-RDU, they’ll be near Chicago normals! The upcoming storm will be, oddly enough, when the stratospheric polar vortex strength is near record highs, near twice the normal strength in terms of zonal winds at 60N!

This is beautiful textbook split flow (from 18Z GFS), the pattern that has given the SE some of its biggest winter storms: N stream has WNW H5 flow to our north in the OH valley bringing the Siberian cold while moist WSW H5 flow is over us and to our south bringing plentiful moisture over the low level cold:

3” would be near Albany alltime record!

A 1/29/2014 last minute repeat?

Like the 12Z it has mainly sleet and ZR here and in much of SE GA. Also, 12Z and now 18Z even more is bringing start of virga earlier.

Regarding 12Z runs as of 3PM, NAM and CMC were a couple of degrees too cold at KATL but Icon, GFS, and Euro were within 1F fwiw.

Just after JAX, CHS did the same: URGENT - WINTER WEATHER MESSAGE NATIONAL WEATHER SERVICE CHARLESTON SC 234 PM EST MON JAN 20 2025 WINTER STORM WARNING IN EFFECT FROM 5 PM TUESDAY TO NOON EST WEDNESDAY... * WHAT...HEAVY SNOW EXPECTED. TOTAL SNOW AND SLEET ACCUMULATIONS UP TO TWO INCHES. * WHERE...IN GEORGIA, BULLOCH, CANDLER, EFFINGHAM, EVANS, JENKINS, SCREVEN, AND TATTNALL COUNTIES. IN SOUTH CAROLINA, ALLENDALE, BEAUFORT, CHARLESTON, COASTAL COLLETON, COASTAL JASPER, DORCHESTER, HAMPTON, INLAND BERKELEY, INLAND COLLETON, INLAND JASPER, AND TIDAL BERKELEY COUNTIES. * WHEN...FROM 5 PM TUESDAY TO NOON EST WEDNESDAY. ————————— * WHAT...HEAVY MIXED PRECIPITATION EXPECTED. TOTAL SNOW AND SLEET ACCUMULATIONS UP TO ONE INCH AND ICE ACCUMULATIONS UP TO ONE QUARTER OF AN INCH. * WHERE...COASTAL BRYAN, COASTAL CHATHAM, COASTAL LIBERTY, COASTAL MCINTOSH, INLAND BRYAN, INLAND CHATHAM, INLAND LIBERTY, INLAND MCINTOSH, AND LONG COUNTIES. * WHEN...FROM 5 PM TUESDAY TO NOON EST WEDNESDAY.

Would y’all and others mind posting this kind of thing in banter? Otherwise it will just add clutter to this storm thread. TIA

12Z Euro: Kuchera snow: Sleet: ZR: qpf: 12Z qpf 6Z as comparison showing slight NW trend at 12Z, mainly in NC

12Z Euro: fairly similar to 6Z; so the only major 12Z model without a notable NW/wetter trend though it did trend slightly NW vs 6Z in NC

The Euro has been trending drier for awhile as it had been near the wettest and was correcting toward the others. Will that drying continue with the 12Z or will it now stop or maybe even reverse the drying considering the 12Z model consensus? We’ll know fairly soon.

12Z UKMET starting off better too with a NW/snowier trend since 18Z run yesterday.

12Z GEFS 10:1, though not dramatically so, is consistent with the 12Z model consensus of a snowier/NW trend for many areas vs 6Z. 6Z: 12Z:

Large NW trend on just about everything at 12Z! I’m surprised it isn’t more active in here.