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Area forecast discussion 
National Weather Service quadrant cities Iowa Illinois
1039 am CDT Thursday Jul 10 2014

Update...
issued at 1038 am CDT Thursday Jul 10 2014

High pressure has shifted into the Great Lakes/Ohio Valley areas
with light southerly winds across the dvn County Warning Area. Weak middle level warm
air advection was producing an area of Alto-cumulus over roughly
our northeast third of the County Warning Area but this should push off to our
east as the day wears on. Current temperatures have warmed into
the lower to middle 70s and readings appear on target for afternoon
highs in the upper 70s to lower 80s at most locations.

The swath of smoke from large Forest fires originating in the northwest
territories of Canada has drifted into the County Warning Area. However...visible
satellite shows the smoke is much thinner compared to the past couple
of days. Therefore...this should have no impact on temperatures.

&&

Short term...(today and tonight)
issued at 354 am CDT Thursday Jul 10 2014

The main forecast issue in the short term period is the timing of
potential storms in the western forecast area tonight.

In the near term...surface high pressure remains in place across the
region with dewpoints mainly in the 50s. Expect dry conditions again
today with afternoon temperatures in the upper 70s north to lower
80s south...slightly below normal for early July.

The first in a series of short wave troughs will move into Iowa
tonight. Model consensus has improved regarding the timing of the
wave. Much of the forecast area is now expected to stay dry through
12z Friday. Have maintained chance probability of precipitation across the west after
midnight...with a narrow swath of likely probability of precipitation west of a line from
Vinton...to Williamsburg and Keosauqua. No severe weather is
anticipated.

Long term...(friday through next wednesday)
issued at 354 am CDT Thursday Jul 10 2014

Friday through Sunday...assessing several of the latest 00z run
models and conceptual pattern that they paint/ensemble idea...it
appears the area could be under the mesoscale convective system gun for a good chunk of this
period. Broad upper ridging lays out to almost a zonal flow with
increasing westerlies across the northern third of the middle Continental U.S.. this
temporary before a flux/pattern transition into digging cyclonic
upper flow by Sunday as Canadian/western Hudson Bay vortex sinks
southward. Will walk upstream elevated storm cluster or even an mesoscale convective system
type system across eastern Iowa and the rest of the dvn County Warning Area on Friday in
diurnally weakening fashion. Convective debris keeping temperatures down in
the 70s to low 80s at best. Then the latest signals of the 00z run
solutions suggest west-to-east low level baroclinicity to lay out
parallel to upper level steering flow from across Nebraska...Iowa and into
northern Illinois by Sat evening. Remnant outflow boundary or debris from
the system earlier on Friday to be a player to and may make for a focus
a bit further south than currently anticipated. The low level thermal
gradient/S to be a focus for developing southwesterly low level jet of 30-40+
kts and moisture feed to ridge up over...converge and induce
convection. Again latest thinking suggests this Friday evening
convection to Blossom across Nebraska into western Iowa...with resultant mesoscale convective system
propagating eastward across the local area late Friday night after
midnight. But some signs of initial convection possibly taking off
further to the east across central Iowa into eastern Iowa with sooner
arriving vorticity maximum aloft. Many models paint central Iowa and the
northern half of the dvn County Warning Area with higher coverage of convection...
but again wonder if they may be too far north and that the
southern County Warning Area may be more in line. Will bump up probability of precipitation across much of
the area for now. Extent of warm moist conveyor and convergent
precipitable water feed of over 1.7 inches suggest locally heavy rainfall
possible with any convective system that can organize an make it
across the area...well over an inch by Sat morning. Convection may
then fester into part of Sat...with associated debris and
boundaries undulating all over the place. Much will depend on the
potential of air mass recovery by late Sat in ongoing warm air
advection regime into the area from capped moist source region
just to the south across the southern and central plians...MO/AR
into the western Ohio River valley. The digging upper trough axis
mentioned above and cyclonic middle to upper level jet energy
punching down across the upper Midwest will provide decent forcing
set up along with more enhanced shear profiles Sat night for a
possible severe mesoscale convective system to impact portions or most of the local forecast
area. More heavy rain to also think about of at least 1-2+ inches
by Sunday morning. This bout of rain combined with whatever occurs
Friday night into early Sat could really add up to significant
amounts by the end of the weekend...producing flash flooding...
renewed river/stream flooding or aggravating ongoing river
flooding situations. The latest solutions do suggest that after
any lingering convective complexes exit the area or get shunted to
the south and southeast of the region Sunday morning...just sctrd
and much less organized areas of precipitation may occur later Sunday
into Monday morning. Temperatures a challenge over the weekend but there is
the potential for portions of the area to substantially heat up
and become much more humid. But again convective debris and
boundaries could really mess up high temperature forecasts and will play an
average from north to south for now.

Monday through next Wednesday...latest medium range solutions
continue with the idea...and the 00z run GFS has come on board
big time...about large cold core vortex/cool season looking
pattern set up across the central into eastern Continental U.S. Next week.
Several solutions are advertising a deep l/west upper trough across the
Great Lakes with meridional flow down the upper Midwest out of
Canada/northwestern Hudson Bay region. The main storm track could
be shunted all the way down to the Gulf...while the upper
Midwest/northern plains get inundated with unseasonably strong
Canadian high pressure systems and cold air. Both the GFS and
European model (ecmwf) now advertise single digit 850 mb mb temperatures into or very close
to the dvn County Warning Area from Monday night through at least next Wednesday. If enough
cloud cover...some signs that high temperatures during from Tuesday into
Wednesday/middle next week may struggle to get out of the 60s...and record
or near record low temperatures possible overnight if skies clear out and
surface winds decrease enough. Will trend down temperatures at the end of the
extended period for now...and await any further model or
teleconnection agreement in the runs over the next few days. ..12..

&&

Aviation...(for the 12z tafs through 12z Friday morning)
issued at 639 am CDT Thursday Jul 10 2014

Generally VFR conditions for the taf cycle. After morning ac
clear...expect fair weather cumulus developing to sctrd levels at 4-5k feet above ground level
while south to southeasterly surface winds of 6-12 kts blows across the
area. Isolated showers or thunderstorms will be possible this
afternoon...but such low coverage expected that not Worth placing
mention in the tafs. Winds will go light southeast in the
evening...then there will be a chance for clusters of showers and
thunderstorms to approach the area from the west toward dawn Friday
morning. The Cid terminal will have the best chance to have some of
this activity get into the vicinity toward the end of the taf period.
The precipitation will be elevated and have a good chance of having a VFR
base as it arrives. ..12..



&&

Dvn watches/warnings/advisories...
Iowa...none.
Illinois...none.
MO...none.
&&

$$

Update...haase
short term...rp Kinney
long term...12
aviation...12

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