Sunrise 6:25 AM   Sunset 8:14 PM Moonrise 12:00 AM   Moonset 8:19 AM

  Print   HELP   Reset   Save   Recall

FXUS63 KTOP 281919 AFDTOP

Area Forecast Discussion National Weather Service Topeka KS 219 PM CDT Sun Apr 28 2024

KEY MESSAGES

- Storms exit to the east this afternoon.

- Could be some patchy ground fog Monday morning.

- Active pattern with some potential for severe thunderstorms persists for Tuesday through Thursday.

DISCUSSION
Issued at 218 PM CDT Sun Apr 28 2024

19Z water vapor imagery showed a closed upper low over western NEB. The associated surface low was noted in the obs over east central NEB with a stretching south through northeast and south central KS. Showers and storms along the boundary have been sub- severe thanks to cloud cover preventing much in the way of destabilization ahead of the front. This activity along with the surface front is forecast to be east of the forecast area by 00Z. Clearing skies and diminishing surface winds may allow from some ground fog to develop Monday morning. Forecast soundings from the RAP and NAM have not been that bullish on fog in part to some wind at the top of the boundary layer and drier dewpoints moving in from the northwest. But given recent rains and not much mixing of the boundary layer this afternoon, think the models may be under doing the fog potential. Have only added some patchy fog in the favorable low lying areas for now, but later shifts may need to reevaluate the potential for fog.

Monday brings a break from the thunderstorm activity with subsidence behind the exiting wave providing mostly sunny skies. With good insolation have bumped up highs a few degrees with middle 70s expected for most locations. There are signs from the operational models for some weak warm air advection developing Monday evening.
Moisture return looks muted so don't think it will amount to much, but it is something to keep an eye on nonetheless.

Better moisture return develops Tuesday and through mid-week. Models are in good agreement with a shortwave passing mainly north of the forecast area into Tuesday evening. While the better dynamics look to stay north of the area, the wave is progged to push a frontal boundary into the area with a narrow axis of CAPE between 2000 and 3000 J/kg developing ahead of the front. Bulk shear of 40KT to 50KT maybe enough for some organized updrafts. So will need to keep an eye on convection late in the afternoon Tuesday and Tuesday night.

A moist and unstable boundary layer is progged to remain in place for Wednesday, but forcing for vertical motion is not obvious.
Shower and thunderstorm activity could be higher Wednesday night as the low level jet increases and provides some lift for convection to form on. Another frontal system is forecast to move through the central plains Thursday as a more amplified shortwave trough propagates east. There is good agreement in the models with the timing of the front so the NBM has some high POPs with this feature.
GFS forecast of 0-6km bulk shear is less than stellar for severe weather, probably due to a relatively weak wind field forecast. But given the time of year we'll need to monitor this for the severe potential in the coming days.

Operational solutions show the deeper moisture getting displaces to the east and south for Friday through Sunday. But the model blend holds onto some small POPs through the weekend indicative of greater spread from the ensembles. Looking at the 500MB cluster analysis from the 00Z runs shows that negative height anomalies could end up anywhere from northern MN to CO. Given the uncertainty, have stuck with the model blend in what is a low confidence POP forecast. This increase forecast spread also tends to smooth out temperature anomalies. But even the operational runs don't show persistent warm air advection. So temps generally remain mild with readings near or a little above normal.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/
Issued at 1202 PM CDT Sun Apr 28 2024

Scattered showers and possibly a thunderstorm will move west to east through the afternoon and should pass to the east of TOP and FOE around 22Z. CIGS should also improve above 3KFT once the SHRA move east. Think there could be some ground fog develop around dawn Monday. Will keep visibilities MVFR for now since RAP and NAM forecast soundings don't completely saturate the boundary layer.

TOP WATCHES/WARNINGS/ADVISORIES
None.

Full Color Weather Map

Link to Loop


Other links: GEOS-West     Contential US     Full GOES-East

Topeka, KS,