117
FXUS63 KTOP 020730
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
230 AM CDT Tue Jul 2 2024

.KEY MESSAGES...

- Heat advisory in effect today and unchanged from previous
forecasts.

- The first of several potential severe weather threats sets up
across the area today by mid afternoon as a modified cold front
enters northeast and north central Kansas.

- Severe weather may be possible in at least some form through much
of the 4th of July week due to little change in the overall weather
pattern.

&&

.DISCUSSION...
Issued at 226 AM CDT Tue Jul 2 2024

The overall upper air pattern continues to exhibit gradual changes
over the past 12 hrs. The eastern long wave trough has worked off
shore into the Canadian maritime region. A semipermanent anticyclone
remains over the southern and southeastern CONUS. Return of
subtropical moisture and a LLJ is set up on the northwestern flank
of this anticyclone and in between a broadening cyclonic flow regime
which is setting up across the northern CONUS. A modified surface
cold front is positioned through central Nebraska within and
inverted pressure trough and surface low pressure back into
southeastern Colorado and southwestern Kansas vicinity.

An embedded vort max continues to work through eastern Nebraska into
Iowa at this hour. Storms associated with resultant DCVA ahead of
this feature have been trending down below severe limits early this
morning. Parallel mean winds have led to a series of flash flood
warnings along the Platte River valley over southeastern into east
central Nebraska areas. This is also along the cold frontal boundary
which will advance southeast into the area later today. A few
showers continue to form along the 305K surface from north central
Kansas areas and mainly along the KS/NE border region. This is
expected to continue through early morning with the LLJ streaming
across the region before it veers slightly and weakens after sunrise
today. Not anticipating this area to broaden in coverage
substantially with convergence being limited across the area and
lapse rates not very conducive to convective development being
favored.

Deeper moisture looks to be in place across the forecast area for
this afternoon. Moist flux convergence increases by this afternoon
along the frontal boundary as it sags into the area. This will
support intense heating today with insolation being intense into the
afternoon. The front working into northern areas should keep the
cooler side over Hwy 36 areas so the heat advisory remains unchanged
at this point. Severe weather looks most favorable across much of
the area this afternoon. Initiation could be mid to late afternoon
along the modified cold front as heating erodes the cap and MLCAPES
have a chance to reach to around 4000 J/kg especially along the
boundary into northeastern Kansas areas. The next vort max working
across the central Rockies into the central Plains should arrive by
late afternoon. This may help foster scattered to more widespread
coverage of storms into the evening hours across the area. Still
anticipate the primary hazards to remain damaging wind potential due
to the intense heating aspects leading to DCAPE well in excess of
900 J/kg. Mean flow will be mostly boundary parallel suggestive of
potential for flooding concerns as storm interactions increase with
coverage. Can`t rule out low potential for a tornado but this looks
potentially best northeast of the area into southwestern into
central Iowa areas where potential surface low pressure may cause
locally backed winds where northeast Kansas low level winds appear
to suggest a better setup for southwesterly flow within the BL.
Freezing levels likely around 15kft which would require a strongly
rotating storm or intense updraft for large hail production.

Each day through the 4th of July looks to have potential for severe
weather and additional flood potential across at least portions
of the area with central and east central zones having the best
potential for the modified boundary to stall and waiver back
and forth. Mesoscale details such as outflow boundaries should
ultimately determine where the boundary sets up and thus
differential heating, etc. may become a focus for daily storms
development to take place primarily in concern with the heating
of the day. Thursday (unfortunately on the 4th of July) with
broad cyclonic flow regime still in place overhead, a more
significant shortwave appears to emerge from the northern
Rockies and slip into the central Plains. This may help push a
more organized baroclinic zone through the area by the evening
of the 4th of July. This could lead to the next best organized
severe weather threat should it ultimately materialize.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1220 AM CDT Tue Jul 2 2024

Expect VFR conditions to hold outside of any showers or storms
that develop across the area by late afternoon. Uncertain on the
coverage at this time for any storms along the front so have
gone with a VCSH element to suggest there will be a time frame
where storms may form around the terminals. Wind shear
conditions may be present around FL015 this morning as a strong
LLJ is set up across the area. A few gusts may continue
overnight with a partially mixed boundary layer, however, low
level winds just off the deck may be substantially higher
causing speed shear. FROPA takes place later this evening as the
front moves through the area.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from noon today to 8 PM CDT this evening for
KSZ021-KSZ022-KSZ023-KSZ024-KSZ026-KSZ034-KSZ035-KSZ036-KSZ037-
KSZ038-KSZ039-KSZ040-KSZ054-KSZ055-KSZ056-KSZ058-KSZ059.

&&

$$

DISCUSSION...Drake
AVIATION...Drake