Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Huntsville Alabama
846 PM CDT Friday may 22 2015
with clear skies and light winds in place...temperatures between 7
and 8 PM dropped 5-8 degrees across the area. Temperatures should steadily
fall through the night with forecast lows still in the lower 50s. No
major updates were made tonight outside of capturing the current T/dew point
/issued 619 PM CDT Friday may 22 2015/
for 00z tafs...some blow off cirrus clouds from convection over eastern OK
will be possible tonight over the taf sites. As low level moisture
slowly increases Saturday afternoon...there could be some scattered cumulus clouds
around 5000 feet by the afternoon. Otherwise VFR conditions are expected through
the forecast period due to a ridge of high pressure over the area.
/issued 300 PM CDT Friday may 22 2015/
after an unseasonably chilly start this morning...sunny skies and
more comfortable conditions prevailed across the central Tennessee
Valley this afternoon. The lowest temperatures noted around the
region this morning were 40 at Russellville and Lynchburg. Highs so
far have warmed into the upper 60s to middle 70s...with light NE winds.
Across the greater North American domain...upper level blocking
continued across the West Coast...resulting in a split flow east of
the Mississippi River. A deep upper low over Quebec was producing
troughing along the East Coast. A northerly flow from a moderating
high pressure now over the region helped create the chilly conditions
yesterday and last night.
The eastern Canadian upper low will continue weakening as it 'lifts'
NE toward the Davis Strait/Greenland...while upper ridging forms over
the Bahamas and southeast coast. While this occurs...the upper block over
the west should finally break down...with its southern low weakening
and moving from Southern California/Nevada to east of The Divide by Sunday.
Energy under the California low will approach the forecast area...and return
rain chances on sun. Beforehand...dry and warmer weather will end the
week. Another somewhat cooler than average night temperature wise is
expected... with lows cooling into the lower 50s with light/variable
winds. Winds for end of the week will become southeast along with return to
seasonable warmth...with highs climbing into the lower 80s. Normal
low/highs for this time of year are 83 and 61.
The southeast flow will gradually bring deeper moisture from the Caribbean
and Gulf across the area for much of next week. This moisture and
greater instability and the approach of upper level energy in the
southern stream will bring rain chances back to the forecast area
during Sunday. With this issuance...kept rain chance over our western
areas on sun...then ending it in the evening. Better chances of
showers and thunderstorms are expected for Memorial Day Monday...as
deeper moisture and instability are realized. Soundings from the NAM
and GFS do not necessarily note high values that hint at severe
weather. But high cape and precipitation water amounts (rising into the 1.6
- 1.8 inch range) Monday into Thursday...locally heavy rainfall and gusty
winds appear the primary threat posed by the stronger storms.
Probability of precipitation wise...stayed with high chance values on Monday
(could get near likely over northwest al). Maintained likely rain chances
on Tuesday/Wednesday coinciding with higher daytime instabilities. Rain chances
diminish somewhat on Thursday/Friday and somewhat drier air moves in across
the region from the west...and upper level ridging reamplifies off of
the southeast coast.
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