Fig. 1.1. The 50-yr. recurrence amount for 24-h rainfall (in.) in the United States.
For example, if the 9-in. contour interval passes through a location, the
climatology indicates one 9-in. rainstorm will occur there in a 24-h period every
50 yr. Figure taken from Schumacher and Johnson (2006).
(a)
(b)
(c)
Fig. 1.2. Schematic of the synoptic flash flood pattern at (a) the surface, (b) 850
hPa, and (c) 500 hPa. Shaded rectangular regions indicate where the greatest
potential for flash flooding exists. Figure and caption adapted from Maddox et al.
(1979).
27
(a)
(b)
(c)
Fig. 1.3. As in Fig. 1.2, except for the frontal flash flood pattern.
(a)
(b)
(c)
Fig. 1.4. As in Fig. 1.2, except for the mesohigh flash flood pattern.
Fig. 1.5. Schematic at initiation time of Type IV extreme rainstorm events in
Minnesota. The median center of the rainstorm is located in south central
Minnesota. Symbols are defined on the right. Figure and caption adapted from
Winkler (1988).
28
Fig. 1.6. Schematic cross section of an elevated convective event taken parallel
to a low-level jet (LLJ) across a surface frontal zone. Dashed lines represent
typical θe values, the large stippled arrow represents the ascending LLJ, the thin
solid oval with arrows represents the ageostrophic direct thermal circulation
(DTC) associated with the upper-level jet (ULJ), and the dash–dotted oval with
arrows represents the DTC associated with the low-level frontogenetical forcing.
The area aloft enclosed by dotted lines indicates upper-level divergence; the
area aloft enclosed by solid lines denotes the location of the ULJ. Note that in
this cross section, the horizontal distance between the MCS and the location of
the ULJ is not to scale. Figure and caption adapted from Moore et al. (2003).
29
Fig. 1.7. A two-stage classification of ET based on the classification of Klein et al.
(2000). The onset and completion times correspond to the definitions of Evans
and Hart (2003). The “tropical” and “extratropical” labels indicate approximately
how the system would be classified by an operational forecast center. Figure and
caption taken from Jones et al. (2003).
30
(a)
(b)
Fig. 1.8. Schematics of landfalling TCs for the composites of (a) left-of-track
rainfall distribution and (b) right-of-track rainfall distribution. The curved black
lines represent streamlines of the upper tropospheric (i.e., 250 hPa) flow. Arrows
represent motion and deep-tropospheric shear with the relative magnitudes given
by the lengths of the arrows. The curved green arrow represents the trajectory of
a parcel starting near the surface in the warm sector and ending in the mid-toupper troposphere in the cool sector. The gray shaded areas represent regions
of precipitation, and pluses and minuses represent the local potential vorticity
(PV) tendency resulting from a combination of advection and diabatic
redistribution of PV. Figure and caption taken from Atallah et al. (2007).
(a)
(b)
Fig. 1.9. (a) Three-hour observed precipitation totals (mm) centered at 1200 UTC
21 June 1972 for the eastern United States. Contours are 1, 5, 10, 20, 30, 40, 60,
and 80 mm. The position of Agnes is indicated by a solid circle. (b) Schematic of
the midtropospheric streamlines associated with possible TC-related flooding.
Figures and captions taken from DiMego and Bosart (1982a).
31
Fig. 1.10. Space–time cross section from IAD to ADW from 2000 UTC 21 June to
0600 UTC 22 June 1972. Isotherms (solid) every 1°C. Conventional cold-front
symbols and abbreviated station model. Six-hour accumulated precipitation (mm)
shown by underlined numbers at 0000 and 0600 UTC. Winds in m s −1 with one
pennant, full barb, and half barb denoting 5 m s −1, 1 m s−1, and 0.5 m s−1,
respectively. Gusts (G) indicated in m s−1. Top numbers represent distances (km)
between stations. Figure and caption adapted from Bosart and Dean (1991).
32
(a)
(b)
Fig. 1.11. Mean sea level pressure (contoured in black every 4 hPa), surface
observations, areas of precipitation (shaded in gray), and conventional frontal
depiction at (a) 0800 EDT 21 September 2000 and (b) 0800 EDT 22 September
2000. Figures and captions adapted from Ulbrich and Lee (2002).
33