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<p class="HTMLBody" align="center" style="text-align:center;line-height:115%"><b><u><span style="font-size:26.0pt;line-height:115%;font-family:"Monotype Corsiva"">Meteorology Seminar<o:p></o:p></span></u></b></p>
<p class="HTMLBody" align="center" style="text-align:center;line-height:115%"><b><span style="font-size:28.0pt;line-height:115%;font-family:"Monotype Corsiva"">Brian Mackey</span></b><span style="font-size:28.0pt;line-height:115%;font-family:"Monotype Corsiva""><o:p></o:p></span></p>
<p class="HTMLBody" align="center" style="text-align:center"><span style="font-size:26.0pt;font-family:"Monotype Corsiva"">PhD Meteorology Candidate<o:p></o:p></span></p>
<p class="HTMLBody"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="doublespacedcaps" align="left" style="text-align:left;line-height:normal">
<b><u><span style="font-size:14.0pt">Title</span></u>:</b> Heavy Rainfall Enhanced by Warm Season Fronts and Orography in Western North Carolina: Synoptic Classification and Physical Drivers<span style="font-size:14.0pt"><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><b><u><span style="font-size:14.0pt">Major Professor</span></u></b><b><span style="font-size:14.0pt">: Dr. Jon Ahlquist</span></b><b><u><span style="font-size:14.0pt;font-family:"Times",serif"><o:p></o:p></span></u></b></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Tahoma",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><u><span style="font-size:14.0pt">Date</span></u></b><b><span style="font-size:14.0pt">:</span></b><span style="font-size:14.0pt"> March 11, 2020
<b><u>Time</u>: 3:30 PM</b></span><span style="font-size:14.0pt;font-family:"Times New Roman",serif"><o:p></o:p></span></p>
<p class="HTMLBody"><b><o:p> </o:p></b></p>
<p class="HTMLBody"><b><u><span style="font-size:14.0pt">Location</span></u></b><b><span style="font-size:14.0pt">:
</span></b><span style="font-size:14.0pt">Werner A. Baum Seminar Room (353 Love Building)
<span style="color:red">NOTE room change</span><b><o:p></o:p></b></span></p>
<p class="MsoNormal" align="center" style="text-align:center"><b><o:p> </o:p></b></p>
<p class="MsoNormal" align="center" style="text-align:center"><b>ABSTRACT</b><b><span style="font-size:12.0pt"><o:p></o:p></span></b></p>
<p class="MsoNormal" align="center" style="text-align:center"><b><o:p> </o:p></b></p>
<p class="MsoNormal">Physical processes that enhance heavy rainfall in association with warm season (April--September) fronts are investigated over western North Carolina. In this region of complex terrain encompassing the basins of the Upper Catawba River,
the South Yadkin River, and the Upper Yadkin River, quantitative precipitation estimates and forecasts exhibit known biases, and a variety of large-scale atmospheric patterns can lead to heavy rainfall and flash flooding. The focus is on events with space-time
dimensions on the meso-$\beta$ scale (horizontally up to 200 km and temporally up to about 12--18 hours). The most frequent internally forced mesoscale weather features that produce such heavy rainfall episodes in the region are mid-latitude fronts. External
mechanical forcing due to the orography of the southern Appalachians also plays an important role in shaping the rainfall intensity and distribution.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">A 17-year climatology comprised of 98 heavy rainfall cases is constructed using daily 4-km stage IV precipitation analyses. Cases are categorized according to the type of front (cold or stationary), front location (if stationary) relative
to the study area (north, south, or over the basins), time of year (April and September vs. May--August), and time of day of peak rainfall. Classical warm front cases are too few to be included in this study. Results show that the majority of warm season heavy
rainfall episodes tend to peak in the afternoon or evening, but there is a notable exception regarding events associated with stationary fronts located south of the basins. These episodes have a nocturnal maximum in rainfall in the foothills of the Blue Ridge
Mountains, suggesting an interaction between the small-scale mountain-valley breezes and a mesoscale easterly low-level jet.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The front type clusters are further evaluated utilizing the latest fifth-generation reanalysis (ERA5) produced by the European Centre for Medium-Range Weather Forecasts. Through the use of percentile rankings, the raw values of precipitable
water and convective available potential energy are transformed into more meaningful and useful quantities that show well-defined maxima in and around the study region. For cold fronts as well as April and September cases of stationary fronts south of the
basins, correlation analysis shows that the presence/strength of an atmospheric river plays a key role in determining the amount and areal extent of heavy rainfall. Also quantified is the low-level upslope flow, which helps regulate the spatial and temporal
variability of heavy rainfall for nearly all frontal regimes in the study. In addition, rainfall events associated with stationary fronts to the north of the basins are heaviest when those fronts retreat farther north and west, coincident with a stronger Atlantic
high pressure cell which increases the low-level moisture transport up the slopes of the Blue Ridge Mountains. For stationary fronts over the basins, the cases with the heaviest, most widespread rainfall are associated with a sharper west-east moisture gradient
from the mountain ridges to the North Carolina Piedmont.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Shel McGuire<o:p></o:p></p>
<p class="MsoNormal">Florida State University<o:p></o:p></p>
<p class="MsoNormal">Academic Program Specialist<o:p></o:p></p>
<p class="MsoNormal">Department of Earth, Ocean, & Atmospheric Science<o:p></o:p></p>
<p class="MsoNormal">1011 Academic Way, 2019 EOA Building<o:p></o:p></p>
<p class="MsoNormal">Tallahassee, FL 32306<o:p></o:p></p>
<p class="MsoNormal">850-644-8582<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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