Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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000 FXUS64 KOUN 202318 AFDOUN Area Forecast Discussion National Weather Service Norman OK 618 PM CDT Tue Apr 20 2021 ...New AVIATION... .SHORT TERM... (This evening through Wednesday) Issued at 206 PM CDT Tue Apr 20 2021 Sky should continue to clear across the region from northwest to southeast late this afternoon and early evening, and gusty north wind will also subside. With dry air in place, dewpoints primarily in the bottom half of the 20s, good radiational cooling conditions will exist at least through the evening hours. Thereafter, mid-high level cloud cover will increase which will be make low temperature forecasts difficult. Majority of the model guidance has the thickest cloud cover over west/southwest portions of Oklahoma and western north Texas after midnight, and farther north and east into central Oklahoma toward daybreak Wednesday. This will leave far north central and southeast parts of Oklahoma with the longest duration of decent radiational cooling conditions. These are the areas where widespread frost is expected, with the cloud cover expected to temper that development. Still think a majority of the forecast area will see a freeze tonight/Wednesday morning, but the increase in cloud cover will likely keep a majority of the forecast area from experiencing a hard freeze (temps 28 deg or colder for at least a few hours). Some of the normally colder locations (low lying areas) may still see temperatures briefly dip into the middle 20s. With this and previous forecast cycles, we are forecasting many areas across the southern half of Oklahoma and western north Texas to break record low temperatures, including OKC, LAW, and SPS which somewhat surprisingly all have the same record for tomorrow, 34 deg. After a cold start tomorrow, still looks like temperatures will recover into the 50s and 60s despite sporadic mid-high level cloud cover. The southerly flow, which will allow moisture to increase ahead of our next weather system, will commence late in the day. && .LONG TERM... (Wednesday night through next Monday) Issued at 206 PM CDT Tue Apr 20 2021 As the surface ridge continues eastward, return flow will strengthen Thursday night into Friday ahead of our next system. Significant moisture advection is forecast to occur ahead of a surface low and dryline that will sharpen over the TX panhandle during the day Friday. Moisture advection and degree of surface heating will be key to surface-based warm sector thunderstorm development ahead of the dryline, as a significant cap is evident on forecast model soundings. The best chance for this to occur will be across southern OK closer to the deeper moisture. Elevated convection may also be possible as a cold front moves southward across northern and central OK Friday evening and forcing from the upper wave arrives. We are still several days out, but given the forecast environment storms across southern OK would be capable of damaging hail and strong wind gusts, with a low tornado risk as well if surface-based storms can develop. The severe risk across northern/central OK would be most likely confined to a hail threat due to the elevated nature of the convection. This cold front will clear the area by Saturday morning, but the airmass behind the front will not be particularly cold. Highs Saturday will still reach into the upper 60s to low 70s. Upper ridging will build over the area Sunday into Monday, with warming temperatures and breezy south winds. Another trough is then forecast by most models to affect the area by next Tuesday, with uncertainty surrounding timing and the degree of moisture return across our area. At this point, the greatest risk for thunderstorms and any associated severe weather looks to be focused across the eastern half of OK. Ware && .AVIATION... (00Z TAFS) Issued at 613 PM CDT Tue Apr 20 2021 VFR conditions are expected through the TAF period. Gusty northerly winds will slowly decrease this evening, becoming variable tomorrow throughout the day. An increase in mid-level clouds are expected early tomorrow morning. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 31 59 42 56 / 0 0 0 20 Hobart OK 30 59 41 55 / 0 0 0 20 Wichita Falls TX 32 61 44 59 / 0 0 10 20 Gage OK 27 57 37 55 / 0 0 10 10 Ponca City OK 29 58 37 54 / 0 0 0 30 Durant OK 32 62 45 63 / 0 0 10 10 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...Freeze Warning from 1 AM to 9 AM CDT Wednesday for OKZ004>048- 050>052. TX...Freeze Warning from 1 AM to 9 AM CDT Wednesday for TXZ083>090. && $$ SHORT TERM...11 LONG TERM....08 AVIATION...13

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