FXUS63 KEAX 261138
AFDEAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
538 AM CST SAT DEC 26 2009

...UPDATED AVIATION DISCUSSION...

.DISCUSSION...

MAIN CHALLENGE OVER THE NEXT FEW DAYS DEALS WITH EMBEDDED SHORTWAVES 
ROTATING AROUND THE MAIN UPPER VORTEX OVER THE CENTRAL CONUS AND ANY 
KIND OF PRECIPITATION CHANCES ASSOCIATED WITH THOSE WAVES.

SYNOPSIS:
A LARGE VORTEX WAS CUTOFF FROM THE FLOW AND SPINNING OVER THE 
CENTRAL CONUS. AROUND THE CORE OF THIS VORTEX...ROUGHLY OVER THE 
MIDWEST...SEVERAL SHORTWAVES WERE NOTED VIA WATER VAPOR AND THE 
PV1.5 PRESSURE SURFACE. ONE WAVE WAS MOVING SOUTHWARD THROUGH 
NEBRASKA AND INTO NORTHERN KANSAS EARLY THIS MORNING WITH ANOTHER 
SMALLER WAVE NOTED OVER IOWA. THESE EMBEDDED WAVES WERE HELPING TO 
MAINTAIN LIGHT SNOW/SNOW SHOWERS ACROSS THE REGION. AT THE 
SURFACE...LOW PRESSURE WAS SITUATED OVER SOUTHERN IOWA AND HAS BEEN 
WEAKENING THROUGH THE NIGHT HOWEVER THE PRESSURE GRADIENT HAS BEEN 
STRONG ENOUGH TO KEEP WINDS IN THE 15 TO 20 MPH RANGE WITH A FEW
STRONGER GUSTS.

TODAY AND TONIGHT:
WITH THE SURFACE LOW AND THE PRESSURE GRADIENT CONTINUING TO WEAKEN 
WINDS ARE EXPECTED TO WEAKEN AS WELL AS A RESULT. THIS WILL DECREASE
THE AMOUNT OF BLOWING SNOW AND WITH ONLY LIGHT SNOWFALL ANTICIPATED
WILL DROP THE WINTER WEATHER ADVISORY WITH THIS FORECAST ISSUANCE.
THE EMBEDDED WAVE MOVING INTO NORTHERN KANSAS THIS MORNING IS
EXPECTED TO ROTATE THROUGH THE AREA TODAY...WHICH WILL LEAD TO
CONTINUED CHANCES OF LIGHT SNOW. WITH HOW LIGHT THE SNOW HAS BEEN
SOME MINOR BLOWING AND DRIFTING CAN STILL BE EXPECTED THROUGH THE
DAY. SNOW ACCUMULATIONS SHOULD BE LIGHT WITH LESS THAN AN INCH
EXPECTED THROUGHOUT THE AREA. THE DIURNAL RANGE IN TEMPERATURES
SHOULD ONCE AGAIN BE LIMITED DUE TO THICK CLOUD COVER. AFTERNOON
HIGHS SHOULD BE ABLE TO CLIMB INTO THE LOW TO MID 20S THROUGHOUT THE
FORECAST AREA.

ADDITIONAL EMBEDDED WAVES WILL LIKELY ROTATE OVER THE REGION DURING 
THE OVERNIGHT AND AS A RESULT WILL CONTINUE TO MENTION LIGHT
SNOW/SNOW SHOWERS THROUGH THE NIGHT. AS WITH DURING THE DAYTIME
PERIOD ANY SNOW AMOUNTS WILL BE LIGHT AND SHOULD BE LESS THAN HALF AN
INCH OR SO OVERNIGHT. LOWS SHOULD NOT DROP OFF TOO MUCH FROM THE
AFTERNOON HIGHS AS CLOUD COVER AND WINDS WILL KEEP TEMPS GENERALLY IN
THE MID TEENS.

SUNDAY THROUGH MONDAY:
THE UPPER VORTEX WILL CONTINUE TO INFLUENCE THE FORECAST AREA. 
THINKING THAT THE MAIN SYSTEM WILL BE FAR ENOUGH EAST THAT ANY 
ADDITIONAL SNOW WILL LIKELY BE IN THE FORM OF FLURRIES OR JUST VERY
LIGHT IN GENERAL. SO WILL ONLY KEEP SLIGHT CHANCE POPS GOING WITH NO
ACCUMULATIONS. A FEW FLURRIES MAY PERSIST INTO SUNDAY NIGHT ACROSS
OUR EASTERN COUNTIES BUT FEEL THE BEST CHANCES WILL BE ACROSS EASTERN
MISSOURI...CLOSER THE UPPER LOW...SO WILL KEEP MENTION OF ANYTHING
OUT OF THE GRIDS FOR NOW.

HIGHS FOR SUNDAY WILL LIKELY STILL STRUGGLE WITH CLOUD COVER 
LINGERING AND NORTHWESTERLY WINDS CONTINUING. BY MONDAY MORNING 
CLOUDS SHOULD BECOME THIN ENOUGH THAT BETTER RADIATIONAL COOLING MAY 
OCCUR. WINDS MAY NOT COMPLETELY DROP OFF BUT WITH SNOW COVER ACROSS 
MUCH OF THE AREA VERY COLD LOWS IN THE SINGLE DIGITS TO MID TEENS 
ARE EXPECTED. THE COLDEST TEMPERATURES WOULD OCCUR OVER THE THICKER 
SNOW COVER ACROSS NORTHWEST MISSOURI. BY MONDAY NIGHT THE 
COMBINATION OF LIGHT WINDS AND CLEAR/MOSTLY CLEAR SKIES SHOULD ALLOW 
FOR VERY GOOD RADIATIONAL COOLING. SO HAVE TRENDED COLDER WITH LOWS 
IN THE LOWER SINGLE DIGITS TO LOW TEENS. DEPENDING ON HOW THE 
SURFACE HIGH MOVES THROUGH THE REGION COULD SEE COLDER TEMPERATURES 
PARTICULARLY OVER THE THICK SNOW COVER.

CDB

&&

.AVIATION...

SEVERAL VORT MAXES ROTATING AROUND PARENT VORTEX CENTERED ACROSS IOWA
THIS MORNING. TIMING THESE INDIVIDUAL WAVES AND RESULTANT HEAVIER
SNOW SHOWERS MAY PROVE TO BE A CHALLENGE. BELIEVE OCCASIONAL SHOW
SHOWERS WILL OBSERVED THROUGH THE DAY AT ALL TAF SITES AND HAVE
BASICALLY CARRIED TEMPO GROUPS TO ACCOUNT WHILE ATTEMPTING TO TIME
THE NEXT WAVE TO SLIDE OUT OF IOWA AND TOWARD THE TERMINALS LATER
THIS MORNING. OTHERWISE...WINDS WILL GRADUALLY SUBSIDE THROUGH THE
DAY AS SYSTEM CONTINUES TO WEAKEN AND THE PRESSURE GRADIENT RELAXES.
UPPER VORTEX SHOULD BEGIN SLIDING AWAY FROM THE REGION DURING THE DAY
ON SUNDAY. 

DEROCHE

&&

.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&

$$