Scientific Forecaster Discussion

Area forecast discussion National Weather Service Greenville-Spartanburg SC 1052 PM EDT Monday Apr 20 2015 Synopsis... a cold front will cross the area today bringing another round of showers and thunderstorms. Dry high pressure builds in for Tuesday and Wednesday. Another cold front will push in from the northwest on Thursday...possibly bringing showers back to the area. A stronger storm system will move in for the weekend. && Near term /through Tuesday/... of 1050 PM...I will issue a quick update to reduce sky cover and probability of precipitation across the County Warning Area. Temperatures and dewpoints have been adjusted to match observations. As of 930 PM...communication links were restored to our office and radar around 9 PM. At this time...one severe cluster of storms existed across southern Greenwood County. This activity will slide east over the next 45 mins. Otherwise...the primary forecast concern will be the timing and placement of the surface cold front tonight. Latest observation and radar data indicate that the front was located across the southern Appalachians. The front will sweep west through the overnight hours...resulting in veering flow and generally thin cloud cover. Previous discussion... scattered severe thunderstorms will continue to form within low level moist convergence axis in the immediate Lee with a steady expansion along and eventually southeast of I-85 during late afternoon hours. Observed/forecast area soundings depict steep lapse rates and moderate amounts of cape within the hail growth region. Vwp/S and soundings also showing strong and mostly unidirectional wind shear...but localized backing of the near surface flow could result in a some spin-ups. The consensus among the convection allowing models is for discrete deep convection to diminish 22z to 00z...and have tempered probability of precipitation downward accordingly during the period. Progressive Post frontal drying is still on tap for tonight and noticeably cooler air will be seen overnight...with Tuesday morning minimum temperatures closer to the middle April climatology. Continental airmass will linger atop the southeast Continental U.S. Under the large broad very low amplitude upper trough. Lots of sunshine will push maximum temperatures to around normal. && Short term /Tuesday night through Wednesday night/... as of 200 PM Monday...large upper low north of the Great Lakes will contribute to west-northwest flow in the upper levels across the southeast states. Dry high pressure moving across the deep south will dominate the weather in the western Carolinas and NE Georgia Tuesday night into Wednesday. As the upper low moves slowly southeast and a short wave moves southeast through its base...a surface cold front will push southeast across the area Wednesday night. Moisture will be limited with the front due to the deep layer western flow. However...a few showers and thunderstorms may reach the NC mountains by late Wednesday afternoon...but weaken and/or dissipate as they move east into the Piedmont Wednesday night. High pressure will then build southeast into the western carolians and NE Georgia on Thursday. Maximum temperatures will be near climatology on Wednesday and then cool a little below average on Thursday. && Long term /Thursday through Monday/... of 200 PM Monday...high pressure will dominate briefly Thursday night and Friday. An upper low over the desert SW is forecast to move eastward and weaken into a short wave over the Southern Plains and then minor out across the southeast states late this weekend as a large upper low remains over the NE U.S. Both the GFS and ecm develop a surface low near the 4-corners and move it eastward into the Southern Plains and then weaken it as it moves into the deep south by early Sunday. The models develop precipitation across the area Sat as isentropic upglide develops over an in situ wedge. A backdoor cold front then is forecast to move through the area Sat night in the wake of the low. Dry high pressure is forecast to build south over the region during Sunday and continue into Monday. Another southern stream low may bring showers to the region again late Monday. Temperatures are expected to be below climatology through the period. !--not sent--! && Aviation /03z Tuesday through Saturday/... kclt and elsewhere...cold front making its way through mountains and may jump across to central part of forecast area shortly after 00z and then east of area by 03z or 04z. Deeper moisture and associated thunderstorm activity has already cleared east of kclt but until front moves completely to the east of the area cannot completely rule out isolated shower or event thunder...but not Worth mention in any tafs. Best chances for a stray shower or storms appears to be at khky through 02z. Therefore expect VFR conditions to prevail at all airports...with south to southwest winds shifting west to west northwest late this evening behind the front and generally less than 10 kts...with the exception of kavl which will shift more northwest overnight and gust to over 20 kts. Winds stay SW to northwest during the day Tuesday but generally 10-15kt range...and continued VFR with high pressure in control. Outlook...dry high pressure will continue to build in across the region for the middle of the week...leading to low precipitation/restriction chances. Confidence table... 03-09z 09-15z 15-21z 21-00z kclt high 100% high 100% high 100% high 100% kgsp high 100% high 100% high 100% high 100% kavl high 100% high 100% high 100% high 100% khky high 100% high 100% high 100% high 100% kgmu high 100% high 100% high 100% high 100% kand high 100% high 100% high 100% high 100% The percentage reflects the number of guidance members agreeing with the scheduled taf issuance flight rule category. Complete hourly experimental aviation forecast consistency tables and ensemble forecasts are available at the following link: (must be lower case) Www.Weather.Gov/gsp/aviation_tables && Gsp watches/warnings/advisories... Georgia...none. NC...none. SC...none. && $$ Synopsis...jpt near term...Ned short term...lg long term...lg aviation...rnk

Return to Current Conditions

Features

Weather Apps

WunderRadio

Weather Underground Apps
Check out our wide variety of mobile and setup applications.

Weather Underground Applications

Top of Page

Copyright© 2015
Weather Underground, Inc.