481
FXUS63 KTOP 021120
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
620 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 /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 617 AM CDT Tue Jul 2 2024

The main aviation hazards this period will be gusty sfc winds
and the threat for thunderstorms after 21Z. South-southeast
winds increase in the few hours after sunrise, with gusts to 25
kts possible at times. Scattered storms then look to develop
near a boundary this afternoon. Exact timing and location remain
somewhat uncertain so have kept mention of VCSH until confidence
increases. Any storms that develop could contain damaging wind
gusts, large hail, heavy rain and a tornado or two in portions
of northeastern KS.

&&

.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/Teefey