Area Forecast Discussion
Issued by NWS Des Moines, IA

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000
FXUS63 KDMX 180445
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1143 PM CDT WED SEP 17 2014

.SHORT TERM /TONIGHT/...
ISSUED AT 334 PM CDT WED SEP 17 2014

LARGE AREA OF HIGH PRESSURE CONTINUES TO DOMINATE THE AREA AS IT
SLIDES OFF TO THE EAST/SOUTHEAST. LIGHT SOUTHEASTERLY WINDS
EXPECTED OVERNIGHT WITH MOSTLY CLEAR CONDITIONS. EXCEPTION COULD
BE THE FAR SOUTHWEST WHICH COULD SEE SOME INCREASING CLOUDS LATE
TONIGHT AS A WEAK IMPULSE ALOFT PUSHES THROUGH EASTERN NEBRASKA.
TEMPS ALOFT ARE SIMILAR TO TUESDAY NIGHT...BUT HAVE THE SOUTHERLY
FLOW IN PLACE AND INCREASING MOISTURE WHICH SHOULD KEEP TEMPS A
FEW DEGREES WARMER ACROSS THE CWA AND ESPECIALLY ACROSS THE
SOUTHWEST. THEREFORE WENT WITH MIN TEMPS IN THE MID/UPPER 40S
NORTHEASTERN CWA TO THE MID 50S ACROSS THE SOUTHWEST.

.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
ISSUED AT 334 PM CDT WED SEP 17 2014

MAIN FORECAST CONCERN REMAINED FOCUSED ON THE PRECIP CHANCES LATE
THURSDAY INTO FRIDAY AND AGAIN FRIDAY NIGHT THROUGH SATURDAY.
MODELS IN GOOD AGREEMENT UNTIL FRIDAY NIGHT BEFORE SMALL
DISCREPANCIES SHOW UP IN TIMING OF THE COLD FRONT AND THUS PRECIP
FRIDAY NIGHT THROUGH SATURDAY. LEANED CLOSER TO A BLEND OF THE
ECMWF/SREF AS GFS SEEMED TOO SLOW...EVEN THOUGH MODELS HAVE
TRENDED SLOWER OVERALL.

THURSDAY THROUGH SATURDAY...WEAK SHORTWAVE WITH LIMITED MOISTURE
AND INSTABILITY WILL PUSH INTO WESTERN IOWA PAST 06Z FRIDAY AND
SKIRT EAST INTO SOUTHEAST MINNESOTA/SOUTHWEST WISCONSIN BY LATE
FRIDAY MORNING. SOME MID-LEVEL THETA-E ADVECTION AND ENOUGH QG
FORCING PRESENT TO KEEP MENTION OF THUNDER OVER WESTERN TO
NORTHERN PORTIONS OF THE FORECAST AREA. TIMING HAS SLOWED ROUGHLY
3-6 HOURS FROM PREVIOUS FORECAST AND CUT BACK ON POPS TO JUST
NORTHWEST IOWA B/T 06-12Z FRIDAY. THINKING ANY PRECIP SHOULD STAY
NORTH OF I-80...ALTHOUGH A SPRINKLE OR TWO IS CERTAINLY POSSIBLE
FURTHER SOUTH. LEFT OUT MENTION ATTM HOWEVER AS LOW CONFIDENCE
WITH THE EXTENT.

COLD FRONT AND 500MB TROUGH ENTER THE STATE LATE FRIDAY NIGHT AND
PUSH ACROSS IOWA BY 00Z SUNDAY AT THE LATEST. THE MOST SIGNIFICANT
DEEP LAYER MOISTURE REMAINS SOUTH WITH THE REMNANTS OF ODILE IN
KANSAS/MISSOURI. TROUGH LOOKS TO PUSH SOUTH ENOUGH TO KEEP THE
REMNANTS FROM PUSHING ANY FURTHER NORTH THAN THAT. THUS HAVE
LOWER CONFIDENCE WITH SIGNIFICANT QPF. MODELS BREAK APART PRECIP
DURING THE DAY SATURDAY AND LEANED TO HIGH CHANCE POPS WITH BOTH
THE ECMWF/GFS WITH LESSER AMOUNTS VIA THE 17/12Z RUNS.

SUNDAY INTO WEDNESDAY...LARGE SURFACE HIGH PRESSURE BUILDS INTO
THE REGION BY SUNDAY AND DOMINATES THROUGH MUCH OF NEXT WEEK. WENT
COMPLETELY DRY DURING THIS TIME FRAME AS NO SIGNIFICANT SHORTWAVE
LOOKS TO BE PASS OVER IOWA.

&&

.AVIATION...18/06Z
ISSUED AT 1143 PM CDT WED SEP 17 2014

A WEAK DISTURBANCE WILL PASS ACROSS WRN IA TONIGHT.  MID CLOUDS ARE
SPREADING IN FROM THE WEST BUT VFR CONDITIONS ARE STILL EXPECTED
THROUGHOUT THE TAF PERIOD WITH A LIGHT AND VARIABLE WIND.  THERE MAY
BE SOME LIGHT SHOWERS OR SPRINKLES AROUND BUT WAY TOO ISOLATED TO
PUT IN TAFS...WHICH WOULD MAINLY ONLY AFFECT KFOD BRIEFLY FROM 06Z-
08Z.  PATCHY FOG IS POSSIBLE OVER THE NORTHEAST/EAST WITH SKIES
HAVING A BIT LESS CLOUDS AND WINDS BEING LIGHT.  THE FOG SHOULD
MOSTLY BE SHALLOW AND IN LOW LYING AREAS.  THE WIND WILL INCREASE
AFT 16-18Z TO AROUND 10 KTS.

&&

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

&&

$$

SHORT TERM...BEERENDS
LONG TERM...PODRAZIK
AVIATION...FAB


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