Area Forecast Discussion
Issued by NWS Paducah, KY

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FXUS63 KPAH 091132
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
632 AM CDT Wed Apr 9 2014

.UPDATE...
Issued at 632 AM CDT WED APR 9 2014

The AVIATION section has been updated for the 12Z TAF issuance.

&&

.SHORT TERM...(Today through Friday night)
Issued at 313 AM CDT WED APR 9 2014

The 00Z model suite is in pretty good agreement in the general
synoptic picture through the short term period. Surface ridging
over the area this morning will shift gradually eastward,
resulting in winds shifting from northwest to west and eventually
southwest by the end of the day. Aloft, northwest flow will be
relaxing through the day. As a clipper system pushes east through
the Great Lakes region tonight and Thursday, very strong south
southwest winds will develop over our region ahead of the
associated cold front. At this time, it appears that the winds
will stay a notch or two below Wind Advisory criteria. The model
consensus has been very consistent in this regard over the past
few days.

The frontal boundary will move into the northern portions of the
area late Thursday night, and the models have no problem
developing at least elevated instability near and just ahead of
it, so scattered showers and thunderstorms are expected to push
east southeast into the Evansville Tri State area, mainly in the
overnight hours. The 00Z models do differ in the timing and
southward extent of this convection, capped PoPs at 50% along and
north of I-64 and spread slight chances progressively farther
south through the night, possibly on thunderstorm outflow.

At this time, the model consensus does not bring the actual wind
shift much into the area by 12Z Friday, and it actually pushes it
back north rather quickly on Friday. The models are in agreement
in generating surface-based instability over our entire area near the
front, where moisture will pool and temperatures are expected to
climb into the 70s.

The best focus for convection will be near the front over the
northern half of the area, and especially over southwest Indiana,
but scattered showers and storms will possible throughout the
area, as model soundings do not indicate that capping will have
re-established itself over the area yet, and there will be a mid
/upper-level disturbance passing eastward through the region
during the day. Left a lingering small chance in the east Friday
evening. Later Friday night the cap does become a factor and any
moisture will be trapped beneath it. This could result in some
drizzle or very light showers, but not enough chance of measurable
precipitation to mention in the overnight hours at this time.

Not real concerned for severe weather with this system, but some
model soundings are showing anomalously high precipitable water
over the area, so locally heavy rainfall could be an issue on
Friday.

As for temperatures, generally went above or on the high end of
available MOS guidance for lows tonight, Thursday night and Friday
night. Winds will be the main factor tonight, and increased low-
level moisture and clouds should keep it rather mild Thursday
night and Friday night. With the surface ridge still impacting the
region, actually undercut guidance a bit for highs today, leaned
to the warm side Thursday with plenty of sunshine and the gusty
south winds, and then back to the cool side Friday with clouds and
plenty of convection expected across the area. Regardless, it
should be plenty mild through the period.

.LONG TERM...(Saturday through Tuesday)
Issued at 313 AM CDT WED APR 9 2014

The main concern in the long term continues to be a vigorous spring
storm system slated to affect our region in the Sunday through
Monday time frame. The models are still in disarray regarding the
track and timing of the system. Widespread precipitation is likely
with the system...but the details /such as qpf amounts and
convective intensity/ will not be resolved until there is better
model agreement.

As far as the daily details...
Saturday may start off rather cloudy as the remnants of a warm front
linger near the Lower Ohio Valley. Most of the models indicate very
light qpf in the morning. There may be a little drizzle or some
sprinkles...but the chance of measurable precip will be kept below
20 percent for this forecast. The depth of the moist layer will be
confined below 850 mb...and a warm capping layer will inhibit
showers or storms. Abundant low level moisture will make the
temperature forecast a bit challenging. This forecast will have
temps a little cooler than gfs guidance...under the assumption that
considerable cloudiness will linger through the day.

On Sunday...a strong 500 mb shortwave will emerge across the
southern Plains. This shortwave will phase with a northern stream
shortwave before crossing the Mississippi Valley on Monday. Strong
upper dynamics combined with a surge of deep moisture /gfs precip
water values near 1.5 inches/ support the swath of heavy qpf shown
by the models. The best potential for deep convection and heavy qpf
appears to be Sunday night into Monday...along and ahead of the
associated cold front. The main limiting factor for convective
intensity appears to be weak instability...especially if the frontal
passage occurs during the morning hours as the 00z gfs/ecmwf
indicate. The system is still several days away...so the details are
not yet clear.

Much cooler air will flood in behind the cold front Monday night and
Tuesday...along with strong gusty gradient winds. Post frontal
cloudiness and showers will linger at least into Monday night.

&&

.AVIATION...
Issued at 632 AM CDT WED APR 9 2014

Guidance continues to indicate some cu develop by midday at
4-5kft, with the best coverage in the east. Otherwise, the TAFs
will be a wind forecast. Initial light west northwest winds, will
shift to west southwest by midday, and then to south southwest
tonight. All winds should stay at or below 10kts through the
period. The strongest winds are likely to be at KCGI right at the
end of the period, as the pressure gradient tightens significantly
overnight.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&

$$

UPDATE...DRS
SHORT TERM...DRS
LONG TERM...MY
AVIATION...DRS






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