Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Peachtree City Georgia
347 PM EDT sun Apr 19 2015
Short term /tonight through Monday night/...
Quick update to cancel the remaining Tornado Watch.
Warm front is situated across extreme northeast Georgia this
afternoon. Large area of showers and thunderstorms is finally
moving out of the County warning forecast area...but a few strong to severe storms remain
possible through the early evening...mainly in qlcs type segments.
High resolution models do not show much in the way of precipitation
for the overnight hours. Do think after the current precipitation moves out
of the area...there will be a break during the middle to late evening
hours. By sunrise...a cold front will begin approaching the northwest
corner of the state and the chances for showers and thunderstorms
begin increasing again.
There is still some potential for severe weather across portions of
the County warning forecast area on Monday. Across the north...severe weather is less likely
as the front should move through during the early morning hours and
surface heating will be limited. Areas further south should
destabilize the most. In addition...a negatively tilted 500mb trough
will swing though and a coupled upper jet structure will lead to
excellent upper divergence. Steep middle level lapse rates will also be
present. 0 to 6 km shear values have increased a bit to around 50kt.
At this time...think the area that has the most potential for severe
weather Monday will be along and south of a line from La Grange to
Athens. Severe thunderstorms will be capable of producing large
hail...gusty winds and isolated tornadoes. The most likely timing
should be late morning through early evening.
Quiet weather is expected on the back side of the front. Probability of precipitation will
decrease rapidly middle to late evening.
Long term /Tuesday through Sunday/...
no changes made to the extended forecast. Previous discussion is below.
Medium range models are in pretty good agreement through the extended
forecast period...at least west/respect to the larger scale patterns. As
would be expected the later into the run the more there are
differences in strength and timing of some of the smaller features...
but overall a general blend and concentration on the larger scale was
used for the long term forecast grids.
Period starts out with the current system moving into the region
now finally exiting...ushering in a drier and seasonably mild
airmass in its wake through Tuesday. Moisture return begins
Wednesday as the surface ridge slips east of the state. Weak short
waves in the westerly upper flow and a weak cold front bring at
least a slight chance for precipitation back into the north. This
weak frontal boundary hangs around through the end of the work
week keeping slight chance to low chance probability of precipitation in the forecast.
Better chances for rain sweep back in for the weekend as a
stronger short wave sweeps through the region. Both the GFS and
the European model (ecmwf) are generating a decent surface low over the region
associated with this short wave. Enough instability with the middle
week system for a chance of thunderstorms...although lack of
strong dynamics and marginal nature of the instability point to
minimal chances for severe weather. Weekend system showing even
less instability...but stronger dynamics indicate at least a
slight chance for deeper convection.
large area of showers and thunderstorms quickly exiting the
northern terminals. Rapidly improving conditions expected. Winds
should also switch around to the SW side within the next hour.
Should be a quiet night...but IFR ceilings are likely. Tomorrow is
expected to be another active day as a cold front moves through
//Atl confidence...18z update...
medium confidence all elements.
Preliminary point temps/pops...
Athens 63 77 53 70 / 40 60 20 5
Atlanta 64 75 53 68 / 30 50 10 5
Blairsville 59 70 46 63 / 50 60 30 5
Cartersville 62 74 49 68 / 40 50 10 5
Columbus 64 80 55 73 / 30 50 10 5
Gainesville 62 73 52 67 / 40 60 20 5
Macon 64 80 55 73 / 40 50 10 5
Rome 61 73 49 69 / 50 50 10 5
Peachtree City 63 77 51 70 / 30 50 10 5
Vidalia 68 82 60 75 / 50 50 40 5
Flash Flood Watch until 2 am EDT Monday for the following zones: