Area Forecast Discussion
Issued by NWS Topeka, KS

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS63 KTOP 022340
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
640 PM CDT SUN AUG 2 2015

...UPDATE TO AVIATION FORECAST DISCUSSION...

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 307 PM CDT SUN AUG 2 2015

NORTHWEST FLOW CONTINUES ACROSS CENTRAL AND EASTERN KANSAS AT 20Z
WITH A RIDGE OVER THE ROCKIES AND AND TROUGH IN ONTARIO INTO THE
GREAT LAKES. MAIN WESTERLIES REMAIN TO THE NORTHEAST OF THE FORECAST
AREA. SHORT RANGE MODELS DEVELOP SCATTERED TO ISOLATED THUNDERSTORMS
LATE THIS AFTERNOON ACROSS CENTRAL AND EASTERN NEBRASKA. SCATTERED
STORMS HAVE DEVELOPED ALONG A SURFACE TROUGH. THERE ALSO APPEARS TO
BE A WEAK RIPPLE MOVING SOUTHEAST OUT OF WYOMING. EXPECT ISOLATED
THUNDERSTORMS TO DEVELOP EASTWARD IN THE INSTABILITY AXIS FROM
CENTRAL TO EAST NEBRASKA THEN MOVE SOUTHEAST. WILL CONTINUE WITH A
SMALL CHANCE OF PRECIPITATION ACROSS THE NORTHERN COUNTIES FOR THE
EVENING HOURS. SHEAR WILL AVERAGE AROUND 25-30 KTS WITH SBCAPE OF
1500-2500 J/KG COULD SEE A FEW STRONG STORMS WITH WIND AND HAIL THE
MAIN HAZARDS. ANOTHER MILD NIGHT IS IN STORE FOR THE AREA WITH LOWS
IN THE UPPER 60S TO LOWER 70S.

MONDAY A FRONTAL BOUNDARY IS FORECAST TO MOVE SOUTH OUT OF NEBRASKA
AND INTO NORTH CENTRAL AND NORTHEAST KANSAS. MODELS DIFFER HOW FAR
SOUTH THE FRONT WILL GO ACROSS NORTHERN KANSAS, BUT LOOKS TO EXTEND
FROM A LOW PRESSURE TROUGH IN WESTERN NEBRASKA SOUTHEAST ACROSS EAST
CENTRAL KANSAS AND INTO CENTRAL MISSOURI BY 18Z. WILL CONTINUE WITH
SMALL PRECIPITATION CHANCES IN THE NORTH AND EAST IN THE AFTERNOON
HOURS. ATMOSPHERE LOOKS TO BE UNCAPPED LATER IN THE AFTERNOON, BUT
THERE IS LITTLE FORCING ALOFT AND CONVERGENCE ALONG THE BOUNDARY IS
WEAK. HOWEVER EXPECT POOLING OF MOISTURE AND INSTABILITY ALONG THE
BOUNDARY, SHEAR IS MARGINAL FOR A FEW STRONG STORMS TO DEVELOP.
HIGHS WILL VARY FROM THE UPPER 80S NORTH OF THE BOUNDARY TO THE MID
90S TO THE SOUTH OF THE BOUNDARY.

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 307 PM CDT SUN AUG 2 2015

MONDAY NIGHT THROUGH WEDNESDAY...TWO AREAS OF PRECIP POSSIBLE
DURING THIS PERIOD AS FAR NORTHEAST KS NEAR NEARLY STATIONARY
BOUNDARY AND WEAK NORTHERN STREAM SHORTWAVE MAY HELP SET OFF
CONVECTION IN THAT AREA MONDAY NIGHT INTO EARLY TUESDAY. WOULDN`T
EXPECT THIS TO AFFECT MUCH OF THE AREA GIVEN LOCATION OF BOUNDARY
AND WEAK FORCING. OTHER SYSTEM THAT IS EXPECTED TO AFFECT AREA
WOULD BE A WEAK VORT MAX IN THE MORE SOUTHERLY STREAM OF A SPLIT
FLOW THAT IS FORECAST TO SET OFF A CONVECTIVE COMPLEX OVER
WESTERN AND CENTRAL KS MONDAY NIGHT THAT WOULD THEN DRIFT EAST
ACROSS EASTERN KS TUESDAY INTO EARLY WEDNESDAY. MODELS DIFFER ON
AMOUNT OF CONVECTION ASSOCIATED WITH THIS FEATURE AND WHERE IN
EASTERN KS THE HEAVIEST PRECIP WOULD FALL. GIVEN UNCERTAINTY IN
LOCATION...HAVE BLANKETED AREA WITH 40 TO 50 PERCENT POPS TUESDAY
AND TUESDAY NIGHT.

ONLY SLIGHT CHANCE POPS ARE FORECAST FOR WED NIGHT AND THURSDAY AS
EASTERN KS IN BETWEEN SYSTEMS AND ONLY DIFFUSE BOUNDARY IN THE
AREA TO SET OFF ANY ISOLATED CONVECTION. GFS HAS STRONGER LOW-
LEVEL FLOW DURING THIS TIME AND THEREFORE STRONGER ISENTROPIC
LIFT...BUT GIVEN OTHER MODEL AGREEMENT...HAVE KEPT POPS LOW.

DESPITE THE DISAGREEMENT BETWEEN GFS AND ECMWF FOR THURSDAY...ALL
MEDIUM RANGE MODELS HAVE A RECOGNIZABLE SHORTWAVE TROUGH AFFECTING
THE CENTRAL PLAINS/UPPER MS VALLEY FOR THURSDAY NIGHT WITH ANOTHER
GOOD CHANCE OF THUNDERSTORMS. THESE MODELS ALSO THEN TEND TO AGREE
WITH A LULL IN PRECIP CHANCES INTO THE FIRST PART OF THE WEEKEND
BEHIND THAT SYSTEM...BEFORE ANOTHER WAVE AFFECTS THE AREA ON
SUNDAY.

GIVEN QUICK SUCCESSION OF SYSTEMS AND PERIODS OF CLOUD
COVER...HIGH TEMPS ARE FORECAST TO BE ABOUT 5 DEGREES BELOW
NORMAL...WITH MAINLY 80S FOR TUESDAY INTO THE WEEKEND.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 634 PM CDT SUN AUG 2 2015

VFR CONDITIONS ARE LIKELY THROUGH THE TAF PERIOD. WILL CLOSELY
MONITOR STORMS OVER NEBRASKA THIS EVENING AS THEY MAY MOVE FAR
ENOUGH SOUTH TO BRING A WEAK WIND SHIFT OUT OF THE NORTH...OR
PERHAPS EVEN A STRAY THUNDERSTORM NEAR TAF SITES. MOST LIKELY TO
REMAIN VFR THROUGH THE PERIOD THOUGH.

&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...53
LONG TERM...GDP
AVIATION...BARJENBRUCH


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.