FXUS63 KDMX 122016
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
315 PM CDT MON MAY 12 2008

.DISCUSSION...

SHORT TERM (TONIGHT)...GOOD SLY FLOW AHD OF CDFNT...HOWEVER MOISTURE
IS QUITE LMTD.  THIS WILL KEEP PCPN CHCS TNGT LOW IN SPITE OF DECENT
THETA-E ADVN.  FEEL WE'LL SEE ENOUGH MOISTURE LATE TNGT TO KICK OFF
SOME ELEVATED CONVECTION OVER THE SOUTHWEST.  TEMP WILL BE MUCH
SLOWER TO FALL TNGT WITH A STEADY WIND THROUGH THE NGT AND
INCREASING CLOUDS AFT MIDN.

LONG TERM (TUESDAY THROUGH MONDAY)...COLD FRONT WILL PASS THROUGH
TOMORROW...CLEARING OUR FORECAST AREA BY LATE EVENING/EARLY NIGHT
TIMEFRAME. AHEAD OF THE FRONT SOUTH SOUTHEASTERLY FLOW WILL
STRENGTHEN WITH WAA KICKING IN...HOWEVER IT WILL TAKE TIME FOR THE
COLUMN TO MOISTEN SUFFICIENTLY FOR ANYTHING MORE THAN CHANCE POPS.
BY LATE MORNING OR AFTERNOON INSTABILITY WILL INCREASE...WITH THE
MODELS INDICATING MODEST MUCAPE VALUES ACROSS THE SOUTHEASTERN HALF
OF THE CWA...AND BY LATE AFTERNOON DECENT SFC CAPE IN THE
SOUTHEASTERNMOST COUNTIES. IT DOES APPEAR THAT CONDITIONS IN THESE
COUNTIES WILL SUPPORT A CHANCE FOR SEVERE THUNDERSTORMS LATE
AFTERNOON/EVENING AHEAD OF AND ALONG THE FRONT...WITH HAIL SEEMING
THE PRIMARY THREAT. ELSEWHERE...BEST CHANCE FOR RAIN WILL BE ACROSS
THE NORTHERN HALF CLOSER TO THE PARENT LOW...BUT LITTLE IF ANY
THUNDER IS EXPECTED HERE DUE TO LIMITED INSTABILITY. WILL NEED TO
KEEP AN EYE ON RAINFALL IN SOME AREAS SATURATED LAST WEEK...HOWEVER
QPFS DON'T APPEAR TOO HIGH AT THIS POINT.

ANY LINGERING PRECIP BEHIND THE FRONT WILL CLEAR BY AROUND MIDNIGHT
TUESDAY NIGHT...WITH A BRIEF PERIOD OF SURFACE RIDGING ENSUING
BENEATH WEST NORTHWESTERLY MID-LEVEL FLOW. THIS STEERING PATTERN
WILL BRING YET ANOTHER 500 MB SHORTWAVE TO IOWA LATE THURSDAY.
HOWEVER...THE SURFACE REFLECTION WILL BE FAIRLY WEAK AND IT IS HARD
TO JUSTIFY MORE THAN SLIGHT CHANCE POPS AT THIS TIME...PARTICULARLY
AS SOME MODEL RUNS HAVE TAKEN THE PRECIP ENTIRELY SOUTHWEST OF US.
THEREAFTER THE RIDGE IN THE WEST/TROUGH IN THE EAST PATTERN PERSISTS
THROUGH THE END OF THE FORECAST PERIOD WITH NORTHWESTERLY FLOW OVER
OUR AREA SIGNALING SLIGHTLY BELOW AVERAGE TEMPS AND SLIGHT CHANCE
POPS AT BEST. FOR EXAMPLE GFS HAS NOW ABANDONED THE IDEA OF A COLD
FRONT ASSOCIATED WITH A MID-LEVEL IMPULSE ON SATURDAY...BUT SHOWS AN
IDENTICAL SCENARIO ON SUNDAY INSTEAD.

&&

.AVIATION...12/18Z
INCREASING GRAD OVR THE TAF SITES THIS AFTN WILL PRODUCE WIND GUSTS
IN THE 25 TO 35 KT RANGE THRU THE AFTN WITH WNDS BCMG MORE STEADY IN
THE 12 TO 16 KT RANGE AFT SNST.  WX QUITE IN SPITE OF INC MSTR OVR
NGT.  EXPECT TO SEE AN INC IN MID LVL CLOUDS LATE TNGT...BUT PCPN
WILL LKLY HOLD OFF UNTL MID TO LATE MRNG IN THE WRN TAF SITES...AND
AFTN IN THE CENTRAL AND SERN SITES AS A CDFNG APCHS FROM THE W.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

LONG TERM...LEE
SHORT TERM/AVIATION...MS MAY 08