Area Forecast Discussion
Issued by NWS Louisville, KY

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FXUS63 KLMK 060705
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
305 AM EDT Wed May 6 2015

.SHORT TERM (Now through Thursday)...
Issued at 300 AM EDT Wed May 6 2015

The main forecast challenge in the short term will be isolated
precip chances each afternoon/evening.  The GFS proved to be too
optimistic with precip chances for Tues and with virtually no
trigger for today, removed POPs for this afternoon.  A good mid
level cap exists in soundings which should stunt cu growth this
afternoon/evening.

Did leave 20% chance of showers/storms for Thurs afternoon/evening
although highly considered removing those as well.  Both the 0Z
GFS/NAM show a better PV anomaly over the area for Thurs although
both are weak and again a good mid level cap will exist with strong
ridging over the region.

Other than that, above normal temps will continue with highs in the
low to mid 80s today and Thurs, and lows in the mid 50s to lower 60s
tonight. Some light patchy fog will be possible in typical fog prone
areas this morning and again tonight.

.LONG TERM (Thursday night through Tuesday)...
Issued at 300 AM EDT Wed May 6 2015

Southeast CONUS ridge and subtropical low parked off the Carolinas
will combine to form a Rex block pattern Friday through the weekend.
Therefore forecast confidence is moderate at best, especially where
it concerns the precip forecast. Confidence remains quite high that
we`ll see temps solidly above normal, more typical of early June
than early May.

Precip chances will hinge on where the subtropical low ends up
creading a weakness in the ridge aloft. However, even that will
start as a low chance given a lack of low-level forcing and limited
availability of deep moisture. Precipitable water values start to
increase Saturday and especially Sunday, so POPs will ramp up to a
solid 30-50% chance for Sunday. Warmest day will be Friday, with the
first 90-degree day of the season not out of the question in the
typical warmer spots, such as urban Louisville.

By Monday, the southwest CONUS trof should be ejecting out, and the
subtropical low should also be lifting NE up the coast, finally
dislodging the Rex block. Surface cold front should push eastward
across the Ohio Valley. Enough uncertainty in the timing that Monday
POPs will be kept in the chance category. Cooler high pressure will
build in for Tuesday, knocking temps down significantly, but only to
near seasonal normals.

Any bust potential in this forecast is that we may still be too
fast, given the tendency of these blocked patterns to remain in
place longer than advertised by the models.

&&

.AVIATION (06Z TAF Update)...
Updated at 105 AM EDT Wed May 6 2015

High pressure at the surface and aloft will keep winds light and
skies mostly VFR through the TAF period.  There is a chance of some
brief BR/HZ at the terminals around dawn.  Also, some of the models
hint at some very isld convection popping up this afternoon/evening
which may impact the terminals briefly.  However, feel chances of
this happening are too slim for a TAF mention attm.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&

$$

Short Term........AMS
Long Term.........RAS
Aviation..........AMS




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