Area Forecast Discussion
Issued by NWS Wilmington, OH

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804 FXUS61 KILN 241743 AFDILN Area Forecast Discussion National Weather Service Wilmington OH 1243 PM EST Fri Feb 24 2017 .SYNOPSIS... A low pressure system will track from the mid Mississippi Valley this morning into the Great Lakes tonight with an associated cold front pushing quickly east across the Ohio Valley overnight. Warm southerly flow ahead of the front will lead to unseasonably warm conditions today. Widespread showers and thunderstorms are expected tonight as the cold front moves through. More seasonable temperatures will spread into the area for the weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... No real change to the forecast today. Region will be warm sectored today. Mid level cap should keep convection from developing this afternoon. Will wait for the line of convection to work in from the west. Strong southerly in the warm sector will produce 25 to 35 mph gusts. Highs in the low to mid 70s still look good. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... The cold front will push east across our area this evening and into the overnight hours. As the front approaches, the cap will continue to weaken and with better mid and upper level forcing moving in from the west, expect fairly rapid shower and thunderstorm development across our west early this evening, then spreading east through late evening into the early morning hours. Some of the higher res CAM models are indicating two lines of pcpn developing across our west, one along a pre frontal trough and then another along the cold front, before eventually congealing into more of a single line across our east through late evening and into the early morning hours. Impressive deep layer shear values will spread in from the west through the evening hours and this will be coupled with an increase in both the 0-1 km and 0-3 km shear values as the front approaches. This will support a primarily damaging wind threat but with cooler air moving in aloft and increasing mid level lapse rates, some hail will also be possible. Several of the higher res models are also hinting at the possibility of a few quasi-discrete cells early in the period across the west. This coincides with a bit of an uptick in updraft speed/helicities across western portions of our fa in the 23z-02z. This will result in an isolated tornado threat through the early evening hours. As the storms transform into more of a QLCS through late evening, the severe threat will transition more to just a damaging wind threat, although an isolated tornado will still be possible with any stronger rotations within the line. Temperatures will remain up ahead of the front but then begin to drop off fairly quickly from the west later tonight as CAA developing in the wake of the front. Lows tonight will range from the mid 30s west to the mid 40s east. Some wrap around moisture will work back into the area through the day on Saturday as the mid level trough axis pivots east across the region. This will result in the possibility of a few rain/snow showers through the day. In addition, a fairly tight pressure gradient combined with some continued low level CAA will lead to gusty winds in the 25 to 35 mph range on Saturday. Temperatures will also struggle to rise much, with readings ranging from the upper 30s west to the upper 40s east. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... Surface high pressure will be centered over Tennessee and Kentucky Sunday morning allowing for temperatures in the mid to low 20s. During the afternoon Sunday surface high pressure will push east with clear skies slowly giving way to some cirrus in the afternoon. This is thanks to a broad upper level trough centered over Canada with pieces of energy rotating east through the base of the trough. By Monday morning the next piece of energy will approach the area from the west. The ECMWF and GFS are slightly different here on a piece of energy that starts out in Southern California on Sunday and eventually pushes east across our area Monday. The ECMWF and GFS both weaken the energy but the GFS holds the energy together slightly longer than the ECMWF. This allows light precip to push into the area Monday morning. The ECMWF solution just doesn`t have enough energy left with the system to produce QPF. Looking at the soundings from the GFS it looks like rain/ snow will be the likely p- type starting off Monday before changing over to all rain Monday afternoon. The ECMWF solution produces quite a different solution though and have kept PoPs chance at best for now. Monday night into Tuesday morning the GFS and ECMWF continue to diverge on solutions with timing between the models moving out of phase. Both models show an upper level disturbance across the Western United States which amplifies and heads east across the forecast area through the middle of the work week. The ECMWF is slower and slightly weaker with the system compared to the GFS. The ECMWF pushes a wedge of PV ahead of the system though and allows rain to start Monday night while the GFS is now slightly more delayed with the onset of precipitation. A warm front will then lift across the area Tuesday allowing temperatures to climb close to 60 degrees again. A surface low will then form Tuesday into Wednesday and push northeast towards Michigan with a cold front extending from the low down to the Gulf Coast. The GFS being much quicker with the energy has the cold front clearing the CWA Wednesday morning while the ECMWF has the cold front clearing the area Wednesday evening. The Canadian is a good compromise between the two and have trended the forecast this direction. For the end of the work week northwest flow will develop on the back side of the trough axis only to have an upper level disturbance push southeast towards the forecast area. As of now both the ECMWF and GFS have the system more across our northeastern zones and therefore have trended the chance of precipitation higher across the aforementioned area. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... The forecast area will be firmly in the warm sector ahead of deepening low pressure and a cold front to our west this afternoon. Scattered cumulus with increasing mid/high clouds can be expected. Winds will be gusty from the south in the upper 20s to lower 30s knots. For tonight, focus turns to the low pressure system and an attendant cold front that is expected to sweep east across the terminals. Widespread showers and the likelihood of thunderstorms remains decent. Have included an MVFR conditional TEMPO group for the best time frame to expect convection. As is typical with thunderstorms, local IFR visibilities may occur within the strongest thunderstorm cores. Region will eventually become "dry slotted" late tonight behind frontal passage. Ceilings should remain in the VFR range in the dry slot until Saturday morning. On Saturday, parent upper level trough will move east across the Great Lakes and Ohio Valley. MVFR post frontal stratocumulus can be expected. Ceilings will lower to MVFR at first before rising back above VFR late in the day. A few rain and/or snow showers will be possible, mainly near the northern terminals as some post frontal instability will be in place. OUTLOOK...MVFR ceilings and visibilities possible Monday, Tuesday night, and Wednesday. && .CLIMATE... Record High Temperatures Date CVG CMH DAY Fri 2/24 72(1930) 72(1961) 67(1930/1961) February Record Highs CVG 76 set 2/10/1932 CMH 75 set 2/26/2000 DAY 73 set 2/11/1999 and 2/25/2000 && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...JGL NEAR TERM...JGL/Sites SHORT TERM...JGL LONG TERM...Haines AVIATION...Hickman CLIMATE...

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