Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 270941 CCA
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
332 AM CDT MON OCT 27 2014

.SHORT TERM /TODAY/...
ISSUED AT 330 AM CDT MON OCT 27 2014

COUPLE OF CHALLENGES FOR THE FORECAST TODAY. TEMPERATURES VERY WARM
AT THE MOMENT AND LOW OVER WESTERN IOWA AND ITS WARM FRONT OVER
SOUTHERN IOWA WILL SLOWLY DRIFT ENE TODAY KEEPING MUCH OF THE AREA
IN THE WARM SECTOR THROUGH EARLY AFTERNOON. DESPITE A WIND SHIFT AT
THAT TIME...VERY LITTLE COOL AIR BEHIND THE TROUGH. THEREFORE...HAVE
RAISED HIGHS OVER ALL OF THE AREA WITH MID TO UPPER 70S FROM CENTRAL
THROUGH SOUTHEAST TODAY. CLOUDS COVERAGE MAINLY BROKEN TODAY...WITH
SUNSHINE/CLOUD MIX FOR MUCH OF THE MORNING AND EARLY AFTERNOON.
SOUTHERN SECTIONS CONTINUE IN THE MID 60S AS OF NEARLY 3 AM THIS
MORNING AND OUR TEMP AT THE OFFICE HAS NOT FALLEN MUCH SINCE 06Z.
NEXT CHALLENGE WILL BE POP TODAY. THOUGH AMPLE SURFACE MOISTURE WILL
ADVECT NORTHEAST WITH THE LOW AND WARM FRONT...SOUTHEAST/EAST
PORTION CAPPED FOR MOST OF THE MORNING AND THIS WILL LIMIT ANY
SHOWER THUNDER THERE UNTIL MID TO LATE AFTERNOON TIME FRAME. OVER
THE NORTHWEST...MAIN AREA OF EXPECTED SHOWERS WILL BE ASSOCIATED
WITH THE APPROACHING H500 SYSTEM OVER THE NORTHERN PLAINS. BY MID
AFTERNOON TROUGH WILL ALREADY BE EAST OF I35 WITH SLIGHTLY DRIER AIR
WORKING INTO THE CENTRAL COUNTIES. SO...TWO AREAS OF POSSIBLE
SHOWERS TODAY...SHOWERS AND ISO THUNDER IN THE EAST/SOUTHEAST MAINLY
FROM 20Z THROUGH 00Z AND SHOWERS OVER THE NORTHWEST/NORTH
CENTRAL...FROM 18Z TO ABOUT 23Z...DIMINISHING DURING THE AFTERNOON
AS THEY MOVE EAST. MOST OF THE MESO GUIDANCE HINTS AT THIS SCENARIO.
NAM/GFS NOT VERY BULLISH ON FORCING/PRECIP CHANCES. EURO MOST
AGGRESSIVE IN DEVELOPING SHOWERS/STORMS EAST OF I35 THIS AFTERNOON
BUT WITH LIMITED FORCING AND CAP TO OVERCOME...WILL TREND TOWARD
LESS AGGRESSIVE SOLUTIONS TODAY. WINDS PICK UP BEHIND THE BOUNDARY
AND WILL BE GUSTY FOR A WHILE THIS AFTERNOON NORTHWEST/WEST.
OTHERWISE...THE LAST IN A SERIES OF MILD OCTOBER DAYS WITH COOLER
WEATHER TO FOLLOW.

.LONG TERM /TONIGHT THROUGH SATURDAY/...
ISSUED AT 330 AM CDT MON OCT 27 2014

CLOSED 300 MB LOW WILL TRACK FROM CENTRAL NORTH DAKOTA TO EASTERN
LAKE SUPERIOR BETWEEN 00Z TUE AND 00Z WED...WITH THE ATTENDANT
TROUGH AXIS PIVOTING ACROSS THE CWA EARLY ON TUESDAY MORNING. THE
DEEPENING SURFACE CYCLONE WILL BE QUICKLY EJECTING NORTHEAST FROM
SOUTHERN WISCONSIN TO EASTERN LAKE SUPERIOR BETWEEN 00Z AND 12Z
TUESDAY...DRAGGING THE SURFACE COLD FRONTAL BOUNDARY ALONG WITH
IT. CONTINUED THE TREND OF PREVIOUS FORECAST PACKAGES AND SPED UP
THE DEPARTURE OF PRECIP AFTER 00Z TUE AND EXIT THE PRECIP FROM THE
CWA BEFORE 05Z. ALSO REMOVED THUNDER WORDING FROM THE FORECAST
FROM 00Z ONWARD GIVEN THE DECENT INHIBITION ABOVE ANY ELEVATED
INSTABILITY. STRONG UPPER LEVEL QG FORCING AND MID LEVEL VORT MAX
TIED INTO THE UPPER LEVEL WAVE COULD STILL RESULT IN CLOUDS
LINGERING THROUGH THE FIRST PART OF THE OVERNIGHT...BUT GIVEN THE
INFLUX OF LOW LEVEL DRY AIR IN MODEL SOUNDINGS...HAVE LEFT POPS
DRY. THIS IS IN AGREEMENT WITH HIGH RES NMM/ARW MODEL GUIDANCE.

STRATUS IS EXPECTED TO OVERSPREAD THE NORTHERN HALF OF THE STATE
TUESDAY MORNING ON THE BACKSIDE OF THE DEPARTING LOW AND APPEARS
TO BE HANDLED DECENTLY BY THE NAM/GFS. THE ONLY REAL QUESTION WILL
BE HOW FAR SOUTH THE CLOUDS SHIELD DROPS AND AT THIS POINT HAVE
KEPT PARTLY TO MOSTLY CLOUDY WORDING NORTH OF HIGHWAY 20. WINDS
WILL ALSO BE ON THE INCREASE ON TUESDAY AS HIGH PRESSURE BUILDS
BEHIND THE DEPARTING LOW. KEPT THE STRONGEST WINDS UP IN THE
CLIMATOLOGICALLY FAVORABLE NORTH WHERE THE PRESSURE GRADIENT IS
ALSO THE TIGHTEST.

AFTERWARDS THE SYNOPTIC PATTERN OVER THE CONUS AMPLIFIES
SUBSTANTIALLY WITH RIDGING BUILDING OVER THE INTER-MOUNTAIN WEST.
ONE WEAK WAVE WILL DIVE ACROSS THE NORTHERN PLAINS IN THE
DEVELOPING NORTHWEST FLOW LATE WEDNESDAY AND EARLY THURSDAY.
MODELS HAVE BEEN FLIP FLOPPING ON WHETHER OR NOT ANY PRECIP WILL
COME OF THIS SYSTEM. STUCK WITH A MODEL BLEND IN THIS REGARD AND
KEPT TOKEN POPS IN THE EAST. OTHERWISE LOOK FOR QUIET WEATHER
THROUGH THE END OF THE WEEK AND THE BEGINNING OF THE WEEKEND WITH
THE RIDGE MIGRATING THROUGH. NEXT CHANCE OF RAIN WILL BE SUNDAY
AND MONDAY ALONG A LIFTING WARM FRONT OUT AHEAD OF AN APPROACHING
LOW.

TEMPERATURES LOOK TO FALL BACK TO NEAR AVERAGE AFTER THE
DEPARTURE OF THE FIRST SYSTEM ON TUESDAY. LOWERED HIGHS SLIGHTLY
IN THE NORTH BASED ON THE GROWING CONFIDENCE IN A PERSISTENT
STRATUS/STRATOCU DECK. TEMPERATURES FALL TO SLIGHTLY BELOW NORMAL
FOR THE END OF THE WEEK AND THE BEGINNING OF THE WEEKEND AS A
STRONG CANADIAN SURFACE HIGH PRESSURE CELL SINKS SOUTH BEHIND
THURSDAYS SYSTEM.

&&

.AVIATION...27/06Z
ISSUED AT 1200 AM CDT MON OCT 27 2014

BOUNDARY WILL PUSH INTO THE STATE OVERNIGHT AND CROSS THE FORECAST
AREA ON MONDAY. WHILE CONDITIONS WILL MAINLY BE VFR WITH THE
PASSAGE OF THIS BOUNDARY...SOME MVFR VISIBILITIES AND CEILINGS
WILL BE POSSIBLE AROUND DAYBREAK MONDAY NEAR KFOD AND KMCW WHERE
LIGHTER WINDS AND MOISTURE CONVERGENCE WILL LEAD TO POSSIBLE LIGHT
FOG AND LOW CLOUD DEVELOPMENT. HOWEVER...WITH OVERALL LOW LEVEL
MOISTURE LACKING...RAIN THREAT WILL BE ISOLATED WITH LITTLE
MENTION NEEDED IN THE FORECAST. WINDS WILL BE SOUTHEAST AHEAD OF
THE BOUNDARY BECOMING NORTHWEST BEHIND THE FRONT.


&&

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

$$

SHORT TERM...REV
LONG TERM...SKOW
AVIATION...COGIL



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