268 FXUS63 KPAH 300938 AFDPAH Area Forecast Discussion National Weather Service Paducah KY 338 AM CST Wed Jan 30 2019 .SHORT TERM...(Today through Friday night) Issued at 337 AM CST Wed Jan 30 2019 Many issues to handle in the short term, so will try to handle in chronological order here. Through 6 am CST today... The Arctic front and the leading edge of the Arctic temperatures and much drier dewpoints will have completely moved south of the WFO PAH forecast area (into TN/AR). Forcing and available moisture will also decrease with little, if any additional accumulation of snow expected by daybreak. With an average 20.5:1 snow ratios, minimum snowfall amounts of one half to one inch of new snow can be expected in extreme southern Missouri, the southern Purchase area, and the southeast half of the Pennyrile region of west Kentucky. Given the light (low water content) of the snow, there may be some blowing snow around daybreak in the parts of southeast Illinois, southwest Indiana, northwest Kentucky. Will likely let the Winter Weather Advisory for snow expire at 4 am CST. Any lingering snow should amount to flurries along the AR/TN borders through 6 am CST. Will also attempt to do some messaging about slick roads this morning, especially when traffic increases during the rush hour. From 6 am today through 6am Thursday... The Wind Chill advisory expiration still looks good for Noon, although there may still be some wind chills below -10 degrees along the I-64 counties in southern Illinois through 1 pm. The leading edge of moisture with another minor wave rotating around the intense closed low north of the Great Lakes will move into southeast Missouri and southwest Illinois before 3 pm, slowly expanding southeast through the evening, before shifting northeast and losing forcing by Thursday. At this time, most of the moisture should be wrung out so to speak by midnight tonight. Given the sub-freezing temperatures and potential for road impacts may have to consider another winter weather advisory for snow amounts up to an inch, especially along and northwest of a line from Interstate 57 and route 13 in southern Illinois, westward into southeast Missouri. Lighter amounts, less than a quarter of a inch may be possible over the rest of southern Illinois and into the Pennyrile region of west Kentucky. Will be issuing a new Winter Weather Advisory for parts of southwest Illinois and southeast Missouri for this this afternoon (around 3 pm CST) until midnight for the aforementioned system. Depending on the forcing, the day or evening forecast crew may or may not have to expand east and southeastward. From 6 am Thursday through 6 pm Thursday... A dry period, with warm air advection pushing the southwest half of the WFO PAH forecast area above freezing, with the northeast half of the forecast area holding between 25 and 32 degrees for highs. From 6 pm Thursday to 6 am Friday... Given the density of the air mass and the degree of mixing Thursday night, it will be a race to see how much warming will occur from precipitation loading of warm air into the retreating Arctic air mass as moisture advection increases over the area. The moisture trajectory and thermal advection trajectories will be a key on how much of the shallow Arctic airmass is modified. At this point, anticipate a rapid change over from snow, freezing rain, then rain between 9pm and midnight in the lower elevation areas south of Crowley's Ridge/Shawnee Hills. Between midnight and 6 am Friday, most of the change will be from freezing rain to rain, reaching the I-64 corridor counties just before daybreak. With most of the moisture trajectory and lift shifting from south to southwest Thursday night, QPF (precipitation amounts) should be light and limit the potential for any significant snow or ice accumulation to a minimum. Only concern is the start time. Am concerned that some precipitation may occur in the 6 pm to midnight time frame. Will need to monitor the latest model runs to see if there will be a later onset of precipitation during this time period. For now, I am increase precipitation chances through the evening hours from the south. From 6 am Friday to 6 am Saturday... A quick change over to rain will occur after daybreak on Friday with rain moving east of the area by the afternoon and dry conditions Friday night. Temperatures will remain above freezing for a vast majority of this time. .LONG TERM...(Saturday through Tuesday) Issued at 337 AM CST Wed Jan 30 2019 We continue to watch an upper level wave that will move onto the west coast on Thursday and meander into TX by Friday night. As this feature moves east with time, it weakens and any sufficient moisture and QPF will settle mainly south of our region. This is similar to what models were showing yesterday, so we will continue with mainly dry weather for Saturday and Saturday night. We will see warm air advection continuing as southwest flow strengthens and 850mb temps keep rising. Therefore, highs should have no problem reaching the 50 to 55 degree range on Saturday, with the higher readings in the south. On Sunday, the upper flow pattern becomes more southwesterly as yet another upper wave moves east from the west coast. Models are still having issues on how this system will evolve, but they have improved continuity with the 00z runs. As surface high pressure moves east of the area Saturday night, we will see strengthening low level flow out of the south, which will cause a decent increase in moisture as well as warmth. In fact, given the 850 mb temp progs, it continues to look like many locations will reach 60 degrees or above on Sunday. Highs close to 60 degrees would be about 15 degrees above normal. If the latest GFS guidance is close to being correct, we could be approaching record highs for Sunday in some locations. A low pressure system develops to our west on Sunday and we continue to watch its progression eastward with time. Light showers could be possible Sunday afternoon but better chances arrive Sunday night as the front approaches. There are still differences in the timing of the FROPA with the ECMWF continuing to be the faster solution. We will linger rain into Monday, accounting for the slower operational and ensemble solutions. Continued above normal temperatures will occur on Monday, as we remain ahead of the front. Therefore, upper 50s to lower 60s will be likely for highs on Monday. Big issues in the operational model data when it comes to Monday night into Tuesday. Stark differences in surface analysis between the GFS and the ECMWF/Canadian and it looks like its based on timing. The GFS indicates dry high pressure building in over the area for Monday night into Tuesday, before another system comes barreling out of the Rockies toward the region, bringing more rain chances. The ECMWF/Canadian indicate a much quicker return of moisture and rainfall. One thing the models do agree on, is that there are no major intrusions of cold air showing up, so even though the front moves through, temperatures will remain in the 50s for highs on Tuesday. That may change however, looking ahead to mid to late week when temperatures drop back down to more normal levels. && .AVIATION... Issued at 1153 PM CST Tue Jan 29 2019 Primarily VFR conditions are forecast through the period. With the passage of an arctic front, a band of light snow showers will continue to progress south across portions of southeast Missouri, far southern Illinois, and western Kentucky overnight. This activity will temporarily reduce ceilings to MVFR and visibilities to MVFR/IFR. The activity was already tapering off at KEVV as of midnight and should end at KPAH/KOWB by 08Z. Accumulation will be fairly light, but may be up to an inch or slightly more in some areas. A fair amount of sunshine Wednesday morning will be impeded by increasing mid level clouds during the afternoon ahead of yet another minor disturbance, which may bring light snow showers to central and southern portions of the area during the evening. Brisk northwest winds in the morning will tend to subside by afternoon, then become light and variable by evening. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...Winter Weather Advisory until 4 AM CST early this morning for ILZ087>094. Wind Chill Advisory until noon CST today for ILZ075>078-080>094. Winter Weather Advisory from 3 PM this afternoon to midnight CST tonight for ILZ075-080-081-084-085. MO...Winter Weather Advisory until 4 AM CST early this morning for MOZ086-087-100-107>112-114. Wind Chill Advisory until noon CST today for MOZ076-086-087-100- 107-111. Winter Weather Advisory from 3 PM this afternoon to midnight CST tonight for MOZ076. IN...Winter Weather Advisory until 4 AM CST early this morning for INZ086>088. Wind Chill Advisory until noon CST today for INZ081-082-085>088. KY...Winter Weather Advisory until 4 AM CST early this morning for KYZ001>022. Wind Chill Advisory until noon CST today for KYZ004-005-007-010- 013>016-018>021. && $$ SHORT TERM...Smith LONG TERM...CW AVIATION...RJP