Area Forecast Discussion
Issued by NWS Des Moines, IA

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000
FXUS63 KDMX 271128
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
626 AM CDT SAT JUN 27 2015

.SHORT TERM /TODAY/...
ISSUED AT 254 AM CDT SAT JUN 27 2015

MAIN FORECAST CONCERN DURING THE SHORT TERM PERIOD WILL BE SHRA/TSRA
CHANCES THIS AFTERNOON. CWA REMAINS IN PREDOMINANTLY NORTHWEST FLOW
ALOFT...IN BETWEEN SHORTWAVES...WITH WEAK SURFACE FLOW MAINLY OUT OF
THE NORTHWEST TO NORTH. ADDED SLIGHT CHANCES POPS FOR TSRA THIS
AFTERNOON ACROSS THE EASTERN CWA. CAPES BECOME SLIGHTLY ELEVATED
THERE...AS HIGH AS 1000 J/KG...AND CONVECTIVE TEMPERATURES OF 75 TO
80F SHOULD BE ACHIEVED. BOUNDARY LAYER WILL BE SUFFICIENTLY MOIST AS
WELL...WITH SFC DEW POINTS AROUND 60F JUST ENOUGH ENERGY WOULD BE
AVAILABLE FOR MAINLY SHRA POSSIBLY SOME TSRA. HIGH-RES MODELS HINT
AT THIS POSSIBILITY AS WELL. HOWEVER RELATIVELY DRY FORECAST
SOUNDINGS ALONG WITH OVERALL NVA ALOFT WILL PRECLUDE ANY
WIDESPREAD ACTIVITY AND ORGANIZED HEAVY RAINFALL. OTHERWISE...MADE
ONLY MINOR CHANGES TO FORECAST MAX TEMPERATURES TODAY.

.LONG TERM /TONIGHT THROUGH THURSDAY/...
ISSUED AT 254 AM CDT SAT JUN 27 2015

AFTER RECENTLY ENDING THE PATTERN OF ZONAL FLOW...WE WILL SETTLE
INTO NORTHWEST FLOW THROUGH MUCH OF THE LONG TERM THANKS TO THE
HIGH BUILDING OVER THE MOUNTAIN WEST...A SLOWLY EXITING LOW OVER
THE GREAT LAKES...AND NO OTHER MAJOR PUSH THROUGHOUT THE CONUS.
TEMPERATURES THROUGH THE PERIOD WILL GENERALLY BE SEASONABLE OR ON
THE COOL SIDE WITH NO MAJOR SWINGS. WHILE THE NORTHWEST FLOW IS
SET IN PLACE...WE WILL BE FAIRLY ACTIVE AS SHORTWAVES MOVE
THROUGH THE SYSTEM...BRINING ABOUT SHOWER AND STORM CHANCES ON A
NUMBER OF DAYS.

THE PRIMARY DAY OF CONCERN LOOKS TO BE SUNDAY WITH THE GREATEST
CHANCES FOR POPS AND POSSIBLE SEVERE WEATHER. BEGINNING EARLY
SUNDAY MORNING POPS WILL INCREASE AS A RIGOROUS SHORTWAVE BEGINS
TO MOVE INTO NORTHERN IOWA. STORMS APPEAR TO BE ELEVATED IN THE AM WITH
THE BIGGEST THETA-E/COLD PUSH ABOVE THE SURFACE AND IN THE
850-700MB LAYER. THROUGH THE MORNING HOURS NORTHERN IOWA WILL
LIKELY SEE SOME THUNDER...BUT CERTAINLY ON THE SUB- SEVERE SIDE
WITH MUCAPE VALUES UNDER 1000 J/KG. MUCAPE VALUES BY THE AFTERNOON
WILL LIKELY BE AROUND 2000-2500 J/KG AS PEGGED BY THE HI-RES
MODELS VERSUS THE GENERALLY OVERLY BULLISH NAM FAMILY...WHICH PUTS
VALUES INTO THE 4000+ J/KG RANGE. SHEAR LOOKS TO BE BORDERLINE
AROUND 30-35KTS...BUT MAY BE ENOUGH TO PRODUCE SOME SEVERE HAIL
WITH RELATIVELY THICK CAPE PROFILES AND GOOD LOW AND MID-LEVEL
LAPSE RATES SHOULD A STORM OR TWO GET ORGANIZED. THAT ALSO ASSUMES
INITIATION AHEAD OF THE PRIMARY ELEVATED THETA-E/COLD PUSH...WHICH
WOULD MUDDLE CHANCES OF DISCRETE STORMS AND ORGANIZATION.

INTO MONDAY AND BEYOND...THE STORY WILL BE REPETITIVE WITH SHORT
BREAKS FOLLOWED BY WEAK SHORTWAVES PUSHING THROUGH THE NORTHWEST
FLOW THAT WILL BRING ABOUT PERIODIC SHOWERS AND STORMS THROUGH THE
AREA. NO ONE DAY LOOKS OUTSTANDING OR OF CONCERN AT THE MOMENT
WITH REGARDS TO WIDESPREAD SEVERE WEATHER GIVEN A LACK OF MAJOR
FORCING...INSTABILITY...AND OTHER SUPPORT.

&&

.AVIATION...27/12Z
ISSUED AT 626 AM CDT SAT JUN 27 2015

MVFR CONDITIONS DUE TO FOG IN SOME LOCATIONS WILL GIVE WAY TO VFR
CONDITIONS BY 14Z DUE TO DAYTIME HEATING. ISOLATED SHRA AND PSBL
TSRA MAY AFFECT THE KALO AND KOTM TERMINALS THIS AFTN THRU 00Z.
THEN...A THUNDERSTORM COMPLEX OVERNIGHT MAY PUSH INTO IA FROM THE
MN/SD AREA...AFFECTING THE KFOD TERMINAL.

&&

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

$$

SHORT TERM...ZOGG
LONG TERM...CURTIS
AVIATION...ZOGG


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